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High fuel flow indication

BigJohn

Well Known Member
Over the past month I made several cross-country flights, and tweaked the Dynon K factor as specified in the Dynon manual. Got it to the point where my fuel used (by Dynon) and fuel added (at the pump) were within .1 gallons. Pretty darn good, and was starting to feel confident in the Dynon readings.

Then - on my most recent trip, on climbout from Muskegon, MI, I got a high fuel flow alarm and a reading of over 10 GPH, up from the usual full throttle climb flow of 6.5 GPH. I leveled at cruise and the high reading continued. (I have the Dynon downloaded data file at the time of the incident.)I was clearly not really burning that much gas, as the engine continued to run fine and my actual consumption was normal for the leg. When I pulled the fuse for the electric boost pump, the flow returned to normal. This happened again on the next leg. Sudden onset, electric pump OFF back to normal, electric pump ON back to high rate. On my last leg all was normal.

I have yet to pull the top cowl and check the fuel pump for any signs of trouble - plan to do that tomorrow but would be surprised to see anything obvious. Is it possible the electric fuel pump is overpowering the engine driven pump and forcing extra fuel back through the return line? And why would this be happening intermittently? By any stretch of the imagination could this be a failure mode of the old style pump, and should I plan to replace it?

I have discussed this with Van's Support - they could not recall anything previous like this. They recommended I call Lockwood - spoke with their technician and got no help. I have just put messages out on both the Dynon and Rotax Owner's forums

Any advice/theories appreciated.
 
How about fuel pressure?

John, You have the download, right? Take a look at fuel pressure at the time of the high fuel flow incidents. As a matter of fact, scan the fuel pressure for the whole flight.

If your FP was dipping lower than normal, you may have the same syndrome I had...which was cured with a new engine-driven fuel pump.

Jim
 
John, You have the download, right? Take a look at fuel pressure at the time of the high fuel flow incidents. As a matter of fact, scan the fuel pressure for the whole flight.

If your FP was dipping lower than normal, you may have the same syndrome I had...which was cured with a new engine-driven fuel pump.

Jim

John,
I think Jim is right. My does the same thing (with high pressure). The fuel pressure control mechanism is inside the mechanical fuel pump...it does not like dealing with two pumps. I put a temp on/off switch in (wired next to the electric one) with plans to buy a new fuel pump when they come out...which I understand Lockwood now has. Yes I know it shuts the avionics fans off...I just basically switch it off for a few seconds then back on and all works well for a little while. Hopefully the new pump will solve lots of problems.

Pete
 
my actual consumption was normal for the leg.
John,
That means that fuel was not leaking nor was the engine using more than normal. That leaves two possibilities:
1. The flow sensor is going bad and is lying.
2. The flow sensor is telling the truth and the excess fuel is being returned to the tank.
Let's assume that fuel is being returned to the tank at a rate higher than normal. There are two possibilities for that:
1. The return line orifice has gotten bigger.
2. The fuel pressure has gone up.
It is unlikely that the size of the orifice has changed. So let's assume that the fuel pressure has gone up. The Dynon data log can be checked to confirm this scenario. If the fuel pressure has gone up, then a pressure relief valve (if built-in) internal to one of the pumps could have failed. Higher pressure causes higher flow rate.
Joe Gores
 
beginning of the end

John,

Save yourself some trouble and get a replacement pump. This is the beginning of the end of that pump. I believe the pump is sucking air. These symptoms are the same if you drain the tank through the gas collator and as air is inducted the flow goes up while pressure goes down. Its insidious with this problem. As you trouble shoot it is on again and off again until the engine will only run on partial power then you got a problem. Good luck
 
No change in fuel pressure.

All,

Thanks for all the responses. The funny thing is, there was no change in the pressure before, during, and after the incident.

Tomorrow I will pop the cowl off and check for stains at the weep hole.

Anybody know off hand if this type of pump failure has been covered under warrantee? And, what the procedure is to submit a claim?

Another question - I notice the new pump comes in two flavors, with and without the hoses. Which type would I need if I decided to bite the bullet and just order one?

John
 
Hey BigJohn - -

About $180 for bare pump. About $575 with hoses. If warranty, and it should be for you, get the one with hoses. You have to pay for it up front, and wait for a couple months to get your money back. This assumes you can prove it is leaking.

John Bender
 
IIRC there are four weep holes in the pump. Because car gas doesn't leave convenient blue stains like avgas, you may need to use a swab with some kind of solvent to pick up evidence of leakage. These pumps have been known to leak along the two crimped seams also. Because Rotax policy on warranty replacement requires statement of leakage, you really want to find something.

I think I am the only one who ordered just the replacement pump. I didn't want to roll the dice on $500 and I had put special insulation on my fuel hose already. It was not difficult to carefully Dremel off the clamps on the pump. Somebody on your airport likely has the stainless clamps and tool for the factory-like re-installation of hoses.

The service center will send you the forms. Of course the English instructions are in fine print, so be careful to fill it out correctly. I was told by Lockwood that they would likely make good on my claim because, "Rotax knows there is something wrong with those fuel pumps."

Here's hoping the new, improved models are more reliable.

Jim
 
Just a thought......

If ordering the fuel pump with hoses, I would ensure Van's did not somehow SPECIAL order the engine with hose lengths designed for the RV-12.

Anyone know??
 
It was not difficult to carefully Dremel off the clamps on the pump. Somebody on your airport likely has the stainless clamps and tool for the factory-like re-installation of hoses.

There is a nice video on the EAA website showing the removal, installation and the tools required to remove and/or install these clamps on the hoses and then another for the firesleeve.
 
Yes the pump with the hoses will work!

John P,
The pump with the hoses will work in the RV12. Ask me how I know! Just because the pump is not leaking doesn't mean that its still not going bad. Ask Jim how he knows. All you have to do on the Paper work for the return is State, "After testing the pump per the Rotax Maintenance manual it was found to lose pressure intermittently, possible leak in pump. Replaced with new pump part #893114". This is the part number for the new pump with the hoses attached per the Rotax-owner.com web site. Go back and read this thread:
http://www.vansairforce.com/community/showthread.php?t=66775&highlight=fuel+pump

See my post Dated: 05-08-2011, 09:56 PM The basic symptom of pump failure is first a leak or no leak (Ask Jim how he knows):confused:with High fuel flow in to the red followed by an Alarm tone on the Dynon. Next a decrease in fuel pressure which occurs at a slower rate then the fuel flow symptom. Fuel Pressure may not go to zero just down into the yellow with no alarm. As I have stated before this is a very insidious problem. You may have had a Hiccup like Marty had or with more flying over a period of time if the pump is going bad the symptoms will become more pronounced. I don't think the engine will stop running altogether it will just start to lose some power. So you might want to try some more flying till you see the symptoms. Good luck and let us know how it works out.

This maybe the link to the EAA video that Marty was talking about I think.
http://bcove.me/3mztmj1l
 
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Very busy last couple of days but I did get to the hangar yesterday long enough to pull the cowl. The fuel pump is bone dry with no leakage stains. The electric pump produces about 1.8 PSI which increases somewhat when I pull the engine through by hand. I still have more questions than answers. Hopefully things slow down a bit tomorrow and I will have time to ponder my next move.

Thanks to all who have responded with information and thoughts.

John
 
Thanks to all who have responded. I need all the help I can get - I am NOT a mechanic, and yet I now feel I have been thrust into that realm by this issue, which with my limited expertise, seems quite complex. If you will humor me, I will try to organize my current questions, and reply to some of the above.

To David Paule - correct, no leak.

To Jim N223JH - Fuel pressure was steady.

To Peter K. - I wish I understood better the internals of the pump. But PRESSURE does not change. Indication of FLOW is what changes.

To Joe Gores - I like your logic, however, there is no discrenable rise in fuel PRESSURE that I can see on the data. How can the FLOW increase if the PRESSURE remains constant?

To Marty - Thanks for the data analysis. I will call you to dicuss when I have some time. I need your help to inperpret the graphs.

To RDOG - I believe you, but where would the pump be sucking air FROM?

To John Bender - How in h*ll can those two hoses be worth $395?! That is blowing my mind! And as I understand it, I can only get warrantee replacement if the pump is leaking.

To N223JH (again) - Jim , I only find two weep holes in the pump. There are no stains on those or around the crimp. (Was running 100LL during incident, so should show blue stain.) I will look at it again to try and find the other two holes. My inclination is to order just the pump with the barbed fittings, as you did, since I think there is a high risk of not getting the warrantee payment..

To Marty (again) - I downloaded the pertinent pages of Rotax SI-912-020 R5, and that document has nice pictures of the new pump, hoses, etc., but no hose length specified. That seems odd. Are we just to assume the lengths are the same as the old ones? Now here's a new twist. There is a statement in the SI that if an auxiliary electric fuel pump is used there must be a check valve installed in parallel. See 73-00-00 page 7 of 10. Does this mean we should have had this installed all along? Or, does it mean it is specific to the new pump and we need to order and figure out how to plumb in the check valve when we install the new pump?

To Jetguy - Thanks for the advice on getting the part paid for under the warrantee. Being a bit of a skeptic, I have to wonder has anyone actully been paid yet using this phraseolgy? Also, see comment above re: the paralell check valve. I'm not sure how to get a definitive answer on that.

I have reached the point where I definitely want to replace the pump, but I'm sure not clear on the details. Anyone, please add more information as you get it.

John
 
John,

I bought the new pump (only) from Leading Edge yesterday. Will let you know what I think following install etc. I'm way past warranty hours and time frame but I did have a bad ignition module ($992) early on and they took care of that. Good luck.

Pete
 
Pump Refund

John,
I bought a new pump with the hoses from LEAF under warranty, Filled out the paper work and returned bad pump, mine leaked, got a full refund within 30 days, no problems. Are you still under warranty? Why dont you think they wouldn't refund the pump under my phraseology? Have you watched the video on Rotax-owner.com about testing the pump? Call LEAF if you want and ask for Linda and tell her the Phraseology exactly as I printed it and nothing else and see what she says. If you cant duplicate the problem again then just keep flying till it occurs again. If you have constant fuel pressure then you pump maybe working fine and you Fuel flow cube could be going bad or has a loose connection. Try resetting your wires at the flow sensor. If you don't want to do that then just by a new pump with out the hoses and reuse your old ones. The pump with out the hoses is around $160.00. When the new pump comes in take it to your local A&P and have him put the old hoses on the new pump for a small fee. Some times something occurs and its just a hiccup in the system, then it goes away, so long as all your other engine indications were fine and the engine continues to run smoothly just fly some more.;) Good Luck
 
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How can the FLOW increase

How can the FLOW increase if the PRESSURE remains constant?
According to the laws of physics, the pressure must change when the flow rate changes. Chances are that the pressure is changing but the sensor is not a precision transducer capable of indicating small changes. Now the question is, does the fuel pressure go up or go down when the flow goes up? If the pressure goes up, that means that the pump is putting out more. After thinking about it, that is unlikely. The other guys are probably right that the engine driven pump is leaking air. Either that or the fuel is vaporizing and forming little bubbles. A small amount of fuel vapor or air mixed with fuel will allow the fuel to flow easier with less friction. And so the flow goes up.
Supposing that a person is reluctant to replace the pump due to expense and time and trouble. How can the fuel pump be tested? Here is an idea that I have not tried: Pull up the red knob to close the fuel supply line. Hold bulkhead fitting with backup wrench and disconnect the fuel return line at the firewall shelf and apply about 6psi air pressure to it. Assuming the carburetor float valves stay closed, there should be no leaks. Observe the vent holes on the fuel pump for any sign of leakage.
Air can leak though a hole that is too small for liquid to leak through. When the fuel pump diaphragm first starts to fail, it will have a very small crack. Theoretically, it is possible for air to leak into the pump on the intake stroke without fuel leaking out on the compression stroke.
If the high fuel flow problem goes away after replacing the engine driven pump, then you will know that the pump was defective.
Bottom line is that I agree with the other to replace the pump.
Joe Gores
 
Aux pump!

After going back and rereading your first post I would also check your fittings at your boost pump. You may have a loose one that is causing air to be sucked into your system. Since everything seemed to work fine with the boost pump fuse pulled!;)
 
As an easy check, try seeing if it has a leak when the engine is cold. A hot engine and fuel pump may be evaporating the fuel before you can see it or smell it.

with the engine cold turn on the boost pump for about 10 min and occasionally pull the prop through to get the mechanical pump to cycle. I believe there are four weep holes. Two on the shaft housing and two on the bellows housing. It won't hurt to run the boost pump for this amount of time just be sure you have the fuel valve open.
Good luck, Colin
 
Once, again, thank you all for loaning me your brain power. I checked again yesterday, found all four weep holes with a mirror and flashlight, ran the electric pump for a considerable amount of time , no leaks. Considering all your thoughts and some other advice from the Rotax Owner's forum, my plan is to order just the new pump on Monday. That seems like something I should do regardless, considering all the reported problems with the old style pump. After I remove the old pump I'll send it in for warrantee - if Rotax refuses it, so be it. It won't break me.

I'll use the barbed fittings. My friendly FBO guy will help me make sure I get a good connection. Can't see replacing two perfectly good hoses. (They must be really good, for that price!);)
 
Once, again, thank you all for loaning me your brain power. I checked again yesterday, found all four weep holes with a mirror and flashlight, ran the electric pump for a considerable amount of time , no leaks. Considering all your thoughts and some other advice from the Rotax Owner's forum, my plan is to order just the new pump on Monday. That seems like something I should do regardless, considering all the reported problems with the old style pump. After I remove the old pump I'll send it in for warrantee - if Rotax refuses it, so be it. It won't break me.

I'll use the barbed fittings. My friendly FBO guy will help me make sure I get a good connection. Can't see replacing two perfectly good hoses. (They must be really good, for that price!);)

Good for you John...now we can be "beta" testers together! I just hate being the only one.
 
Another Bad pump

Returned from a long cross country flight last week and noticed fluid on the cowling when I was putting the airplane away. Pulled the top cowl and saw fuel leaks from the weep holes and indications of leaks at the crimp near the edge of the pump. Have started warranty paperwork and ordered a replacement pump with barbs so I can reuse the hoses. New pump requires a drain line and since Van's has not yet received any Rotax engines with the new pump does not have a routing solution for the drain line at this time. My current thinking is to use a 0.25 in aluminum tube routed under cylinders 1&3 to the area near the gascolator and use tubing to connect the aluminum line to the drain barb on the pump.
 
Leakage Drain Line

If Scott McDaniel gets a chance to read this thread before he heads east Ron and I would both be interested in his thoughts on the leakage drain line for the new pump. Yes the old one did just leak onto the muffler but now we have a chance to avoid that and they even recommend it! From Rotax....

Some important considerations for this new style fuel pump assembly:


When installing the fuel pump, a new isolating flange (gasket) must be used.
In addition, the new fuel pump requires an o-ring (part # 631870) between the
fuel pump assembly and the isolating flange (part # 950228)

A "drainage line" must be attached to the bottom nipple fitting to accommodate
potential overflowing fuel / oil in the event of internal pump diaphragm or seal
failure. This drainage line must be routed to an appropriate area away from hot
engine parts etc. It is important that the drainage line be routed to a ram air and
vacuum free zone, it must NOT be routed into the slipstream. The drainage line
must have a continuous slope downward and must be protected from blockage
(e.g. formation of ice).

Maintenance requirements include inspection of the drainage line for damage
including blockage.

The fuel pump cover assembly is held on with 7 screws. This is for assembly
purposes only during manufacturing, the pump is not rebuild-able nor is it intended
that it be disassembled for maintenance.
 
I won't have time to install my new pump before heading off to Oshkosh Monday. Then I'm going to Alaska for two more weeks. I will try to run down Scott or one of the other Van's guys at OSH to see what they are going to do about the drain pipe. By the time I return you guys will probably be flying with the new pump.
 
John,

Have you installed the new fuel pump? Have the higher than normal fuel flows disappeared?

For Marty and anyone else following this topic,

I just got back from the Alaska trip with my friends in the 195. What a blast! Haven't even been to the RV hangar yet. While at Oshkosh I spoke with several of the Van's folks. They told me their engineers are working on the design for the drain tube and the additions to the instructions to cover same. Today I will call them and see how they are coming on that. When time permits this week I will be starting the installation of the new pump.

Meanwhile - has anyone out there installed the new pump, and if so could you post pictures of your drain tube installation?

John
 
New pump installed today

I installed the new pump today. Forgot the camera so no pictures. Cut the old hose clamps with Dremel cutter and pulled off the hoses. Removed the old pump and installed the new one per Rotax instructions. Re-attached hoses using FBO supplied clamps and tensioning tool. Installed drain line (rubber fuel hose) and routed it across bottom of engine well away from hot parts. Secured next to drain line from oil tank, cut off even with same. Secured with cable ties. Ran up to check for leaks - fuel pressure indicating 5.1 PSI - in bottom of yellow, and steady. Installed cowl and went once around the pattern. At full throttle and about 6.5 GPH flow rate, pressure was in top of the green (just under 5 PSI and steady). So far so good. Hopefully problem solved.:)
 
John, did the new isolating flange gasket and O-ring come with the new pump or did you have to order them separately?
 
John, did the new isolating flange gasket and O-ring come with the new pump or did you have to order them separately?

Came complete with new gasket and O ring. All you need to supply is the LocTite for the studs/nuts. You will need a 1/2" crow's foot wrench to adapt your torque wrench to fit in behind the pump.
 
Another fuel pump bites the dust

Just put the plane back together from getting it painted and was anxious to go flying. During the long down period, I had removed the circuit breaker from the electric fuel pump. This morning I forgot to replace the breaker and tried to start the engine. After about 5 seconds of cranking and no starting...I rechecked all controls and noticed the missing breaker. I replaced the breaker and tried to start again and this time it started up. During take-off I received an alarm from the Dynon for High Fuel Flow. It showed 12.5 GPH.

Could my mistake of not using the electric pump initially damaged the engine driven pump?....I wouldn't think so.

This is also the first flight since receiving the dynon unit back after having some repair done. Maybe the issue is with the dynon...?

Your thoughts?
 
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Could my mistake of not using the electric pump initially damaged the engine driven pump?....I wouldn't think so.
I do not think so either. That would not be a very safe design if the engine pump quit whenever the electric pump quit. Not starting within 5 seconds could be explained by the engine pump losing its prime after sitting for a long time.
Maybe the issue is with the dynon...?
The fuel flow K factor could have been changed from where it was set before the repair.
More information and testing are needed. Look at the Dynon data log to see if the fuel pressure dropped significantly when the flow went up. If so, that can indicate a bad engine fuel pump. Check its weep holes for signs of leakage. What was the flow rate and pressure during cruise? Will the engine run with the electric pump off?
The engine pump could be bad. If so, its failure is unrelated to the operation of the electric pump, IMHO.
Joe Gores
 
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Check Dynon Download

Pull the download and check to see what fuel pressure was doing during the high fuel flow event. I cannot imagine how you could have damaged the engine-driven pump.

If your fuel pressure was normal/stable, then you may have an instrument/sender error of some kind. If FP sank in concert, then you were likely seeing the carb bowls filling up and air being blown out of the lines via the carb vents.

In a future flight consider displaying the fuel page front n center on the Dynon. There is nothing consistent with FF and FP from flight to flight on my Dynon. And no apparent correlation with fuel-on-board, altitude or ambient temperature. I think this is why we have a green arc.

Jim
#264
flying 77+ hours
 
Have already replaced machanical pump on engine ! New pump requires a breather line be added. Oriiginal high pressure indication on Dynon came back with new pump! Called Dynon and Vans. System needs new pressure sensor which should be avialable soon. Requires new bracket(F-00036)as old adel clamp will not work. New presure sender has 0-10 PSI range. Original sender has 0-30 PSI range. Probably will require a Dynon update. Parts are supposed to be ready by 11/01/11?
 
Have already replaced mechanical pump on engine ! New pump requires a breather line be added. Oriiginal high pressure indication on Dynon came back with new pump! Called Dynon and Vans. System needs new pressure sensor which should be avialable soon. Requires new bracket(F-00036)as old adel clamp will not work. New presure sender has 0-10 PSI range. Original sender has 0-30 PSI range. Probably will require a Dynon update. Parts are supposed to be ready by 11/01/11?
 
Won't power off

I attempted to download the Dynon data and receive an error message #11. Nothing downloads. The Dynon system is found by the software, and the Dynon unit displays the "yellow" dynon screen. Now the d180 won't power off. The screen states that if I'm "Uploading data" don't power off......well I not uploading so I don't know why it is not turning off. Serial cable is disconnected and master switch is off and the dynon d180 remains on now for over 10 minutes.......How do you shut this thing off???
 
Dynon problem(s)

Actually, I shouldn't say problems. Fact of life with electronics.
Re: Post #33:
I doubt you have a fuel pump problem. Whenever the Dynon has had the software reinstalled or updated several parameters are reset to defaults. One of these is the fuel flow "K-Factor". From previous posts regarding service of the Dynon the factory may not have saved your settings and reinstalled them. You should make a list of those settings whenever updating the Dynon software. Besides K-Factor, the magnetic inclination, and mag intensity will no doubt have to be reset. The How-To is in the manuals;). Look at the K-Factor and a starting point is 90,000. There are previous threads on this, search "K-Factor".

Regarding the yellow screen lockup:
Have seen this happen. The problem was with the driver program for the USB to Serial adapter. (SKYview won't have this problem because the interface is USB). Download the proper driver from Dynon website, Windows 7 uses a different driver than previously.
When we had a yellow screen lockup we called the support number on the screen and they said as long as you were not in the middle of a software change you could power the unit down by turning off the master and sliding the unit out of the panel far enough to disconnect the internal battery. Since no software had been changed it should then boot up OK. Since I don't know exactly what went on before your yellow screen this is only a guess, so you should call Dynon support and discuss it with them.
Also, it sounds like you ran your internal back-up battery down if it ran for 10 minutes and then it went off. You will need to recharge the internal battery.

None of this sounds like you have a big problem, you learn and store it away in your memory banks:).

Tony
 
The screen states that if I'm "Uploading data" don't power off......well I not uploading so I don't know why it is not turning off. Serial cable is disconnected and master switch is off and the dynon d180 remains on now for over 10 minutes.......How do you shut this thing off???
This is a serious situation that might require sending the Dynon back to the factory if not careful. I suggest connecting the cables back up and turning on the computer and running the software again. If you are using a laptop, plug it into an AC outlet. Put a charger on the aircraft battery and turn on the master switch. If the Dynon does not return to a normal screen, leave everything powered on until you contact Dynon support for advice.
Joe Gores
 
Thank you

Thank you all for your quick response to my problem. I followed the directions in the Help file of Dynon and was able to disconnect the batt backup and the unit shut down without issue. I will re-attempt to download data files on Monday when Dynon is open.

Dynon must have changed something during the previous repair and didn't inform me of the changes. Tonight I could communicate with the Dynon and get the version number and also download the firm ware settings. However, each time I would try to download the data files, it would error out. Will talk to Dynon on Monday to resolve. Thanks again.

Steve
 
John,

Save yourself some trouble and get a replacement pump. This is the beginning of the end of that pump. I believe the pump is sucking air. These symptoms are the same if you drain the tank through the gas collator and as air is inducted the flow goes up while pressure goes down. Its insidious with this problem. As you trouble shoot it is on again and off again until the engine will only run on partial power then you got a problem. Good luck

We had a similar problem. The original pump died at 16 hours on a new motor. It was under warranty. The replacement pump gave erratic high pressure alarms (high as 9 pounds at 1600 rpm) with the backup online. We put a mechanical gauge in line that never showed more than the max 6 pounds of pressure. Eventually with a new pressure sending unit gave us the stable readings we were looking for.
 
Have already replaced machanical pump on engine ! New pump requires a breather line be added. Oriiginal high pressure indication on Dynon came back with new pump! Called Dynon and Vans. System needs new pressure sensor which should be avialable soon. Requires new bracket(F-00036)as old adel clamp will not work. New presure sender has 0-10 PSI range. Original sender has 0-30 PSI range. Probably will require a Dynon update. Parts are supposed to be ready by 11/01/11?

Anyone know if the new 0-10 PSI is available yet. I didnt see it on the Dynon Web site.


Brad
 
I will answer my own question .Called Dynon today and the guy on the phone confirmed that they had idenified a new 1-10 psi sensor ,BUT that it would take a Dynon 180 software upgrade and that management had not given them the go ahead to do that. So it looks like a wait and see deal.



Brad Stiefvater
 
I will answer my own question .Called Dynon today and the guy on the phone confirmed that they had idenified a new 1-10 psi sensor ,BUT that it would take a Dynon 180 software upgrade and that management had not given them the go ahead to do that. So it looks like a wait and see deal.



Brad Stiefvater

Thanks Brad. And then Vans will have to approve the "key" for us to download it. Could be awhile but yes it would be nice to have. If it takes too long, I will just install a mechanical one thru the firewall.

Pete
 
Is my mechanical pump failing?

After dealing with a few other issues lately (oil pressure sensor replace, bad float, even a fuel tank leak repair) I am coming to the conclusion that my mechanical pump is now failing and would like to some advise on whether I'm reading this correctly. Rotax is just at the 5 year operating time, hobbs at 470 hours.

First chart is from a short flight earlier in the year and appears to show pretty constant fuel pressure and fuel flow between 5 and 7gph.

Test flight yesterday had very high fuel flow readings - higher than 10gph right after takeoff unless I throttled back below 5000 rpm. Fuel pressure was low on climb out (in yellow) and again on decent from altitude for a short time. In the past I've attributed transient pressure drops to the use of auto fuel. It always recovered after a minute or two, but maybe that has been a symptom of the pump as well. I stayed near the airport and circled to see if it would improve, but it appeared that whenever I pushed the RPM above 5000, I'd get fuel flows above 10 which of course angered the Skyview lady....and me.

I'm leaning towards replacing pump and hoses (I'm at the 5 year mark anyway) before flying again. Make sense?


14jn392.png

wunwwg.png
 
If at 5 years or 500 hours I?d replace regardless of indications since that?s the recommendation. The hi flow and low pressure sounds like vapor bubbles in your fuel line. How old was the fuel you used?
 
If at 5 years or 500 hours I?d replace regardless of indications since that?s the recommendation. The hi flow and low pressure sounds like vapor bubbles in your fuel line. How old was the fuel you used?

Your comment about the fuel stuck a nerve. I had some older fuel in the tank (mix of 1-2 months it turns out) but had added fresh mogas. Had not realized how old the residual fuel was until you mentioned it. I siphoned out all but 2 gallons yesterday and added 16 gal of fresh 93 octane. Flew again and the pressures and flow are all within normal limits. Had not been diligent enough with using fresh mogas and didn't realize these symptoms of using older fuel. Shame on me. Will replace the fuel pump and hoses over the winter in any case. thanks,
 
Trying to help an older friend out in his mid 80's with setting up the fuel tank capacity on a Dynon 1000. He currently shows a maximum of 14.4 gallons in his RV-12, when the actual capacity is 19.8 gallons.

I'm looking for where in the menu to go to adjust the parameters so that his tank readings on the plane jive with the analogue reading on the fuel tank itself. Plane is a 2015 build situated in KWHP here in So CA.

Any suggestions greatly appreciated by old Bob. Also, he notices that if fuel gets topped off up into the neck of the fuel tank, often on take off, the Dynon device will squawk out "high fuel consumption" . Hard to know when fuel has gotten back up into the neck on refill to prevent that audible on take off. Suggestions? Further reading seems to indicate I need to figure out how to get into the K Value also, to adjust indicated fuel usage.
 
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