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  #51  
Old 09-03-2016, 09:56 PM
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RV7A Flyer RV7A Flyer is offline
 
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Location: US
Posts: 1,530
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I assume there's no Lycoming SI for how to replace the pump (which I am thinking I may have to do...been seeing increasing deviations in fuel pressure, with the occasional drop over a few seconds to ~14-15 PSI and then back up, over about 8-10 seconds).

I'll probably add the cooling shroud, although I have a blast tube aimed at it now.

But, my real question here...what sort of sealant is recommended, if any, for the gasket and/or the bolts?
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  #52  
Old 11-27-2017, 07:54 AM
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catmandu catmandu is offline
 
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Default Another thank you for all the tips!

I had suspicions about the low pressure mechanical fuel pump on my carbed O-320 that is 40 years and 1300 hours old. No indication in the logs it had ever been replaced. So I got a new replacement and blocked off a full day. I used a full length ball end hex tool, Hylomar M to seal the gasket, teflon thread sealant on the bolts, fuel lube on the fittings. Made sure the cam was in the proper position, installed the inboard bolt one turn, and was able to tilt the lever arm on the pump under the cam driven piston, no securing tricks required. Then I installed the outboard bolt one turn, and confirmed proper installation by mating the pump to the case easily by hand. Torqued and safety wired the bolts. Full power ground run, no leaking oil or fuel. Two leisurely hours.

What to do with the rest of the day?
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Maryland's Eastern Shore
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Last edited by catmandu : 11-27-2017 at 08:32 AM. Reason: Noted error
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  #53  
Old 11-27-2017, 08:22 AM
krw5927 krw5927 is offline
 
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Location: Wichita, KS
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Quote:
Originally Posted by catmandu View Post
I used a full length ball end hex tool, Hylomar M to seal the gasket, teflon tape on the bolts, fuel lube on the fittings.
What to do with the rest of the day?
The holes for these bolts go completely through to the interior of the accessory case. Teflon tape in general has been discussed a lot on here and generally concluded to be a huge no-no on aircraft. Any danger here of strings of the tape breaking off and doing harm in the oil system or any accessories?
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  #54  
Old 11-27-2017, 08:34 AM
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catmandu catmandu is offline
 
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Quote:
Originally Posted by krw5927 View Post
The holes for these bolts go completely through to the interior of the accessory case. Teflon tape in general has been discussed a lot on here and generally concluded to be a huge no-no on aircraft. Any danger here of strings of the tape breaking off and doing harm in the oil system or any accessories?
Nice catch, thanks for watching out for me. My fingers got ahead of my brain, tape was not used, I edited my post
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Mike C.
Maryland's Eastern Shore
stuck in 1/5th of an Arrow, my partners won't let me go
RV-6A bought flying
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  #55  
Old 12-23-2017, 05:47 PM
Jab Jab is offline
 
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Location: Tampa, FL
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Hi all

I have an O320 in a RV4 and had a fuel pressure drop in a full power climb, which caused the engine to lose power until I turned the electric pump on and went back to the airport. The engine would run ok at lower power settings but not at full power.

Pulled the pump off and found two hard “granules” of some crumbly substance which were obstructing the diaphragms, holding them open. One granule in each diaphragm. Weird! After thoroughly cleaning the pump and gascolator I reinstalled it.

I had not found this thread so I had to figure this out myself and surprisingly, it worked quite well. I put the bolts through the housing and held the pump in place, ensuring the arm was in the correct position. I found if I tilted the pump clockwise, I could get the left bolt in easily and tightened it up, only enough to keep the flange faces aligned but the pump could still be rotated. I then pushed up on the right side, rotating the pump against the spring pressure on the arm to get the right side bolt hole to line up. It took a couple of tries to get the threads to take but once they did it was easy. Did a run up and had a firm 5 psi, leak checked everything and then did a test flight over the airport. Great fuel pressure at low power but at full power it would drop to about 1 psi, no faltering of the engine though.

However, after reading the threads here, I am concerned about what I did. If overhaul kits are no longer sold because a jig is needed to set the diaphragm pressure, there is no guarantee that my reassembly was correct. I plan to replace the fuel pump anyway since it’s old but it would be nice to fly until I get the new one. I would welcome your opinions.

Merry Christmas,
Gary
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  #56  
Old 12-23-2017, 08:43 PM
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Sam Buchanan Sam Buchanan is offline
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Ground your plane until the pump is replaced. Aircraft Spruce can put a pump in your hands a couple of days after Christmas.
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Last edited by Sam Buchanan : 12-23-2017 at 08:46 PM.
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  #57  
Old 12-23-2017, 09:30 PM
YellowJacket RV9 YellowJacket RV9 is online now
 
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Location: Clearwater, FL / KZPH
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Quote:
Originally Posted by Jab View Post
Hi all

I have an O320 in a RV4 and had a fuel pressure drop in a full power climb, which caused the engine to lose power until I turned the electric pump on and went back to the airport. The engine would run ok at lower power settings but not at full power.

Pulled the pump off and found two hard “granules” of some crumbly substance which were obstructing the diaphragms, holding them open. One granule in each diaphragm. Weird! After thoroughly cleaning the pump and gascolator I reinstalled it.

I had not found this thread so I had to figure this out myself and surprisingly, it worked quite well. I put the bolts through the housing and held the pump in place, ensuring the arm was in the correct position. I found if I tilted the pump clockwise, I could get the left bolt in easily and tightened it up, only enough to keep the flange faces aligned but the pump could still be rotated. I then pushed up on the right side, rotating the pump against the spring pressure on the arm to get the right side bolt hole to line up. It took a couple of tries to get the threads to take but once they did it was easy. Did a run up and had a firm 5 psi, leak checked everything and then did a test flight over the airport. Great fuel pressure at low power but at full power it would drop to about 1 psi, no faltering of the engine though.

However, after reading the threads here, I am concerned about what I did. If overhaul kits are no longer sold because a jig is needed to set the diaphragm pressure, there is no guarantee that my reassembly was correct. I plan to replace the fuel pump anyway since it’s old but it would be nice to fly until I get the new one. I would welcome your opinions.

Merry Christmas,
Gary
For those times where you'd rather not wait or pay shipping, try calling Aeromech @ KLAL, http://aeromech-inc.com/ - they seem to stock a lot of stuff and several times I have made a 5 minute flight over there to buy an odd size bolt or some other small part. I'd recommend you not fly until replacing the fuel pump, but it's still a pretty quick drive from Tampa.

Chris
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