IO-360 quit, would not restart (#1)

Here?s my engine tale of woe. I am looking for any things I should look at, particularly single items that could cause an engine to temporarily stop running and not restart on the ground. All input will be appreciated.

Aircraft: RV-8, IO-360 M1B, Hartzell constant speed prop, 180 hours, last condition inspection Nov 2013, no engne problem previously noted. Oil sample taken 2/2014 (good). Compression 80/78 on all cylinders (Nov 2013).

Feb 3, 2014: A short late afternoon flight(.6 hr) before an anticipated period of bad weather. Basically straight and level profile with altitude up to 5000?. Ground temp was 72 deg F. Field elevation 500?. Fuel approx 15 gal. in each wing tank.

Flight went normal until back in the traffic pattern. I entered via an overhead pattern (1000? agl , 145 ias) and pulled the throttle to idle as I rolled into a 60 deg. bank for the break. Electric boost pump was on and mixture was full rich. Kept the engine in idle until touchdown. On roll out the prop stopped. I was able to roll off the runway and attempted a restart via the start switch. Engine turned over but would not start. Boost pump was still on. I turned off the boost pump and tried various hot and cold start techniques but could not get the engine to fire. Climbed out and walked back to the hangar where I got my truck and pulled the plane back to the hangar. Before pulling it inside I tried one more start, got a tiny bit for fire (really a cough) but it would not start. I was out of time by then and had to leave the aircraft in the hangar.

Due to family illness and bad weather, I did not return to the aircraft for 10 days. I fully expected to find a broken or disconnected mixture cable, but all the engine controls were fine. Before attempting a start, I disconnected the fuel line where it enters the throttle body to check the fuel filter there. I did notice that the fuel seemed to be under pressure in that it spurted out rather than pouring as it normally does. Checked the fuel filter and fuel flow by running the boost pump. Both OK. Started the engine after reconnecting the fuel line, and it started fine after coughing a bit (probably due to air in the fuel line). Since then it has continued to run normally on the ground up to short full power runs on simulated takeoff?s.

I downloaded the Dynon D-180 data (5 sec. interval), and everything seemed normal. It seems evident that the engine stopped generating power when I pulled it to idle in the break. Fuel flow (red cube between boost pump and engine fuel pump) went from 14 GPH to 8 GPH when pulled to idle but remained at 3.5 GPH or greater throughout the pattern. It was reading 4.75 GPH when the RPM went to zero. All other parameters seem normal, and I will post a screen shot of the data in the pattern.

This episode felt just like carburetor icing, but I am fuel injected, or vapor lock, but I had the boost pump on and the OAT was 72 deg F. Also, I have run this engine on days up to 108 deg. F with no vapor lock problems.

I have since done numerous ground runs with no abnormal indications. Here is what I have checked, all without noting discrepancies (unless noted):

1. Fuel flow at entrance to throttle body, exit of throttle body, mixture cut off, and at injectors.
2. Fuel flow with engine driven fuel pump.
3. Fuel filters
4. Fuel injectors
5. Fuel lines for leaks
6. Idle setting (slightly rich)
7. Spark plugs (a little blacker than previous but clean and dry)
8. On/off/start switch
9. Magneto ground check
10. Induction tubes tight
11. Exhaust tight at cylinders
12. Cylinder oil drain hose clamps (loose but not too loose)
13. Engine ground
14. Air inlet system: filter/snorkel/throttle body
15. Fuel tank vents
I have an engine man coming tomorrow and would like to see if anyone can think of anything he should check.

Thanks in advance, John

IO-360 quit, would not restart (#2)

Here is a .jpg of the data dump starting before the incident and including the first unsuccessful ground start. Please note that EGT #4 has been giving me trouble (reading low or intermittently) and needs to be replaced. It often reads -100 deg before engine start.



-John

Default IO-360 quit, would not restart (#2)

OOPS, bad link. Will get data up asap.

-John

Second try on data

Here is a .jpg of the data dump starting before the incident and including the first unsuccessful ground start. Please note that EGT #4 has been giving me trouble (reading low or intermittently) and needs to be replaced. It often reads -100 deg before engine start.



-John

I don't understand the high fuel flow numbers at idle, or not running for that matter. Just off the top of my head, but I'm pretty sure I idle around 1.5-1.7 GPH and taxi at about 2 or a bit more. So I'm seeing double those numbers on your graph for a given idle rpm, and still high numbers for a given 0 rpm, or trying to start I assume.

Hmm, maybe I'm missing something. I mean, on the roll out, at idle rpm, its flowing like 5.3 GPH.. Pretty sure that would flood it.

Interesting..

As mentioned before by previous post the engine will be flooded. If the engine quits while you still have the mixture rich and the boost pump on you will be moving fuel into that engine in the case of fuel injection. (Think priming your cold engine for a start.) If you have the engine quit on the runway with mixture in and the boost pump on you will have to perform a flooded start to have any hope of a restart. Essentially you have been priming this hot engine since the prop stopped turning. You said you did get the engine to cough on your last start attempt before hangering. This would be possible because the flooded condition going away over time.
I have had this situation on an IO-540 and my problems were fuel servo related. The metering system would stick and I would have fuel flow that would be appropriate for a low power cruise while at idle. Sometimes the unit would not stick very long meaning you would have everything check out ok in the maintenance shop. Sometimes it would stick so bad the engine would quit on the landing roll out. Took some time to figure this problem out.
I am not a mechanic and I am not saying that this is your issue. I am just sharing my experience.

I agree, the engine sounds flooded. You're in Texas, so altitude should not be an issue (at high altitude, landing anywhere near full rich can result in a flooded engine). I have had this happen occasionally, and a hot start seems to cure the problem. As previously noted, you were pumping fuel into the engine (at an unusually high rate) for some time, thus very flooded. When I'm idling, fuel flow in my IO360 runs less than 2 gph.

I guess this is not a lot of help, other than to confirm that one can flood the engine a lot and it takes some time to clear. Sounds like all your ground runs afterward were normal, so my only concern would be the high fuel flow that was indicated. Was it also running that high idling on the ground in your subsequent runs? If so, that is what I would check (maybe leak in the fuel system, which could be very bad).

My zero cents worth, since I'm not an engine guy.

Greg

Sounds like the fuel servo

I would recommend giving Don at Airflow Performance a call.
Something is making your servo meter a very high fuel flow at low throttle.

As a quick check, inspect the four pressure sampling tubes that project into the flow ahead of the throttle plate in the fuel servo. bent? damaged? plugged?
If nothing obvious, probably pull the servo and send it in to AFP.

Sounds to me like full rich and a low idle setting has done this. Leaving it full rich and pump on will continue to flood the engine.

ANY.....AND EVERY time you get a flame out in a piston engine the appropriate thing to do is a mixture sweep. It either has too much or too little fuel, and provided there is spark and enough RPM it will fire when the F/A ratio is right.

You may need to adjust your idle mixture setting and your idle speed. Simple to do.

Please email me the full data file so I can see a whole lot of things, and I might be able to offer some advice. This proved very helpful for a recent VAF member

By the way, going full rich in the pattern or on descent is a bad idea....yeah I know that is what your instructor taught you, but it is still a bad idea. There is not one technically good reason for doing so, and plenty of bad ones.

MIXTURE

First, immediately attempting to restart a fuel injected Lycoming that has quit with the mixture rich and the boost pump on is a worst case scenario that should be avoided if possible. I would have pushed the airplane out of the way and let it sit for 10-15 minutes. If you get an induction fire with that much excess fuel, the worst case scenario is losing the airplane.
LEAN LEAN LEAN, the ONLY time a fuel injected normally aspirated Lyc needs full rich is on takeoff below 5000'. ANY other operations, mixture should be leaned agressively.
In the S2B Pitts we reduced power to 25 square and then leaned the mixture to a fuel flow number. I think it was 14 gallons but am not certain. For all other operations the mixture remained at this setting, including full throttle acro, and landing.
If you have to make a go around, above 25", with the prop set at 2700, the engine will start to run rough and this is a reminder that you either need to back off a bit on the throttle or richen the mixture.
Immediately after start I lean the mixture very aggressively. If you forget to reset the mixture for takeoff the engine will not take full throttle.

Flight went normal until back in the traffic pattern. I entered via an overhead pattern (1000? agl , 145 ias) and pulled the throttle to idle as I rolled into a 60 deg. bank for the break. Electric boost pump was on and mixture was full rich.

Maybe I'm missing something...if your engine is fuel-injected, why are you using your electric boost pump for landing?

jmbrwn said:

Flight went normal until back in the traffic pattern. I entered via an overhead pattern (1000? agl , 145 ias) and pulled the throttle to idle as I rolled into a 60 deg. bank for the break. Electric boost pump was on and mixture was full rich.

Maybe I'm missing something...if your engine is fuel-injected, why are you using your electric boost pump for landing?

Click to expand...

I have the same engine and practices the same discipline. My idea of electric boost pump is, primarily, as a back up to the engine driven pump and since in the pattern I am close to the ground, I would like to have that back up ready to go just in case the engine driven pump failed. Although another habit of mine is to stay in close pattern that to make the airport if the engine suddenly died.

I do set my mixture to appropriate level for the given airport elevation and usually throttle is pulled since I am usually at the gliding range to the airport and had the engine go dead as a result of ?priming?

Bavafa said:

I have the same engine and practices the same discipline. My idea of electric boost pump is, primarily, as a back up to the engine driven pump and since in the pattern I am close to the ground, I would like to have that back up ready to go just in case the engine driven pump failed. Although another habit of mine is to stay in close pattern that to make the airport if the engine suddenly died.

I do set my mixture to appropriate level for the given airport elevation and usually throttle is pulled since I am usually at the gliding range to the airport and had the engine go dead as a result of ?priming?

Click to expand...

Same here - boost pump is in case engine pump fails. I also pull to full idle on downwind and typically glide to landing, basically dead stick landing every time (I know, not really dead stick, but rarely do I use any power for base and final). I do not add any mixture in the pattern, especially since I fly primarily out of fields at 5000' or greater.

Greg

Aux Pump

jmbrwn said:

Flight went normal until back in the traffic pattern. I entered via an overhead pattern (1000? agl , 145 ias) and pulled the throttle to idle as I rolled into a 60 deg. bank for the break. Electric boost pump was on and mixture was full rich.

Maybe I'm missing something...if your engine is fuel-injected, why are you using your electric boost pump for landing?

Click to expand...

This seems to be standard procedure for fuel injected Lycoming powered aircraft and is included in the landing checklists of the POH for some (perhaps many) production aircraft that use FI Lyc's.

This is definitely NOT a procedure that one would want to use with a Continental engine as that will flood it and cause it to quit at low power settings.

Skylor

jmbrwn said:

Maybe I'm missing something...if your engine is fuel-injected, why are you using your electric boost pump for landing?

Click to expand...

In case you have to do a go-around.

At least that is what was explained to me when I was trained on fuel injection engined aircraft.

Don't attempt start until you check for fuel in the airbox

I had a similar bigtime flooding problem when I first started my engine. By the time I figured out what was going on, there was 1" or more of fuel accumulated in the bottom of the airbox. Luckily I could see the "waterline" in the bright sunlight. Scary to think what could have happened if I had a backfire with all that fuel laying there. I had to remove the airbox to drain it all out.
Lesson for me? A Silverhawk servo will push a LOT of fuel into the engine on full rich and with the boost pump on.

Thanks for the good inputs. Keep them coming. I have to admit that I am working on the premise that it is something fuel related that centers in the throttle body.

Are you folks saying that the engine flooded (and died) in flight when I pulled it to idle or that it flooded and died after landing as the aircraft slowed? BTW, I have a sniffle valve and noticed that a few drops of fuel were coming out after finally pulling it into the hangar.

For obvious reasons, I am more concerned with the engine stopping than it not restarting.

(When I was new to this engine, I would have trouble with hot starts, but only after sitting for 30-45 minutes. When I would only be stopped long enough to refuel, it would restart fine, although it took more time to catch. I would try a restart immediately after shutdown and it would always restart. Of course, this was without the boost pump priming.

BTW, I called the Lycoming tech support on this and was told to use this technique for hot starts on an IO-360: A few minutes before start push the throttle and mixture full forward while doing the walk around. Make a normal start (mixture idle, throttle 1/4) with no priming or boost pump. I have found that to be quite effective.)

As to high fuel flows, since I installed the red cube between the electrical boost pump and the engine driven fuel pump I noticed higher fuel flows with the pump on in flight. For instance, I would sometimes forget to shut the boost pump off after takeoff wouldn't notice it until I couldn't get the fuel flow right while setting cruise power. Instead of 10-10.5 gph it would be 12-13 gph. As soon as I turned the boost pump off fuel flow would go down to 10-10.5 with no change in airspeed. I often wondered if I was really using more fuel or if it was some kind of anomaly with the red cube. If I was using more fuel, where was it going? It wasn't producing more power.

Engine man coming tomorrow. Thanks again.

-John

If I leave my boost pump on, fuel pressure is higher, but fuel flow always reads normal. That's logical, regardless of setting mixture by EGT or by fuel flo. The engine only needs x amount of fuel at a given operating point.

Rupester said:

I had a similar bigtime flooding problem when I first started my engine. By the time I figured out what was going on, there was 1" or more of fuel accumulated in the bottom of the airbox. Luckily I could see the "waterline" in the bright sunlight. Scary to think what could have happened if I had a backfire with all that fuel laying there. I had to remove the airbox to drain it all out.
Lesson for me? A Silverhawk servo will push a LOT of fuel into the engine on full rich and with the boost pump on.

Click to expand...

A Sniffle valve is a cheap and easy to solution to remedy situation like this. I have it and very glad to have installed it.

In post #1, item #8, the mixture is shown as "slightly rich".

What does this mean to you?

The mixture is either correct, or it is not. And based on your fuel flow numbers, I'd say it is more than a "little" rich. This is assuming the servo has not failed in some way. Anyway, setting idle mixture and RPM would be #1 on my list of corrective action.

And it also sounds like your hot start/clear engine technique is off as well. I suspect that had you cranked the engine with mixture in ICO, boost pump off, and throttle wide open, the engine would have fired in short order and you would not need the tow back to the hangar.

Toobuilder said:

And based on your fuel flow numbers, I'd say it is more than a "little" rich. This is assuming the servo has not failed in some way.

Click to expand...

Based on the numbers that has been given for the FF, I suspect some thing is not right with the RedCube or the K value that has been set for it. Those FF are seem high, and in some cases very high. So, I would not use the FF unless it can be verified.

Have you check the accuracy of the FF reading (i.e. fill up the tank and reset your total fuel if your instrument is capable of doing it. Fly for an hour or two and then refill to see how many gallons you used compare to what is reporting.

As a reference, my FF reported by Redcube does not change if I have the boost pump on or off. The only effect is on the fuel pressure and that is only for a couple of second that goes up from 27 to 33 and comes back to 27 PSI. The FF remains the same if I have the pump on or off. The Redcube is installed between the electric fuel pump and engine driven pump in the "tunnel"

Bavafa,

Having the advantage of seeing the data file the fuel flow figures for takeoff are good, the mixture knob needs a lot of attention however, it is not being used properly on the ground or in flight, and I am providing some advice by email. Most of that can be found in the STICKY John Deakin articles if anyone is interested.

There seems to be some fouled plugs as well as retarded timing. Not to mention the idle RPM and Idle Mixture need looking at.

So I hope John can report back when he has attended to these items.

My apologies for taking a while to respond.

Engine man finally was finally able to get out to the engine. He took quite a while to look everything over and did not find any of the problems he anticipated. No issues with leaning. No fouled plugs. No retarded timing. Idle RPM just fine.

(As others have suggested, he felt sure that the lack of restart on the ground was my trying it with a hot engine and the boost pump on and was, therefore, not part of the problem.)

Since I had told him that the idle mixture was on the rich side, giving a rise of 60 rpm on shutdown in idle, he felt that was the cause. We started and warmed up the engine and he set the idle mixture to 10 rpm rise. After a thorough ground check, I flew for about 30 minutes, circling the airfield with no problems. Have since flown 3 more times with no problems.

BTW, he said that checking the rpm rise at 1000 rpm was more accurate than doing it at idle. He also said, as others have indicated, that a lower rpm rise of around 10 (Lycoming list up to 50 rpm) is the way to go with IO-360's.

Thanks for the good advice.

-John

RV10inOz said:

Bavafa,

Having the advantage of seeing the data file the fuel flow figures for takeoff are good, the mixture knob needs a lot of attention however, it is not being used properly on the ground or in flight, and I am providing some advice by email. Most of that can be found in the STICKY John Deakin articles if anyone is interested.

There seems to be some fouled plugs as well as retarded timing. Not to mention the idle RPM and Idle Mixture need looking at.

So I hope John can report back when he has attended to these items.

Click to expand...

John, good to hear you got it solved