The Murphy Builders Site

I know most of you are gravity feed but I have an Ellision Throttle Body carb
on my 0320 and have to use the mechanical fuel pump.

My fuel pressure has been dropping at engine idle and I have to use my boost
pump to keep the engine running. It does OK in flight with higher RPM but
wants to sputter and quit at idle without the boost pump.

It is worse when at rest in the water when the plane takes a much higher nose
attitude than when on land.

The last flight it even sputtered on take off in the plow position with the
electric boost pump on.

I've checked all the fuel screens and tank vents and found no problems there
so I have ordered a new mechanical pump.

I was told the mechanical pumps usually just give up the ghost and don't
normally fail intermittently over a period of several hours/weeks of time, but if
it is the mechanical pump then this does not seem to be the case with mine.

Does anyone have experience with Lycoming fuel pumps and their behaviors?


Bruce 357R



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Bruce, does this problem happen all the time or just when the engine is hot
(or cold)? I just overcame a heating problem under the cowl by putting
firesleeve on all of the fuel lines. The heat has been reduced enough that
the engine no longer quits at low rpm. I only had the problem with a hot
engine. When I get a chance, I will also insulate the gascolator and maybe
shoot some blast air to it. Like you, I thought the problem was in fuel
delivery and had the fuel pump disassembled and inspected. The fuel
pressure and volume were fine. I've run the engine really hot to test my
solution and everything seems to be working okay. I am sure it will be
completely solved when the insulation and blast tube get installed around
the gascolator.

----- Original Message -----
From: <Legeorgen@aol.com>
To: <murphy-rebel@dcsol.com>
Sent: Wednesday, April 07, 2004 11:22 AM
Subject: Fuel Pump

I know most of you are gravity feed but I have an Ellision Throttle Body

carb

on my 0320 and have to use the mechanical fuel pump.

My fuel pressure has been dropping at engine idle and I have to use my

boost

pump to keep the engine running. It does OK in flight with higher RPM but
wants to sputter and quit at idle without the boost pump.

It is worse when at rest in the water when the plane takes a much higher

nose

attitude than when on land.

The last flight it even sputtered on take off in the plow position with

the

electric boost pump on.

I've checked all the fuel screens and tank vents and found no problems

there

so I have ordered a new mechanical pump.

I was told the mechanical pumps usually just give up the ghost and don't
normally fail intermittently over a period of several hours/weeks of time,

but if

it is the mechanical pump then this does not seem to be the case with

mine.

Does anyone have experience with Lycoming fuel pumps and their behaviors?


Bruce 357R

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I have no experience with Lycoming fuel pumps or the Ellison set-up, but it does seem odd that you still had a problem even with the boost pump on.

When I had my weird problem last year with the dirt in the primer, one thing I learned was that the problem is not always what it seems. I had everything apart on mine, including the carburator, and it wasn't until I finally disassembled my primer (thanks to Wayne for that suggestion) that I found the problem.

Good luck, and hopefully you find it soon. Am looking forward to getting together with you soon for some float flying. Summer has come early for us this year, and if this keeps up, I will be getting in a lot of flying this year.

I should mention that our home field in Langley is having a big fly-in on June 12, and this year they are trying to get as many Murphy planes as possible out. It used to be always dominated by RV's. Maybe you can try make it out for then.

Walter

----- Original Message -----
From: Legeorgen@aol.com
Date: Thursday, April 8, 2004 7:36 am
Subject: Re: Fuel Pump

The problem seems to be worse when engine is warmed up put I can
watch the
fuel pressure drop on the EIS and that's when It begins to
stumble. Engine does
run on the hot side but never had this problems before. It just
surfaced a few
weeks ago and seems have gotten worse.

Bruce



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The problem seems to be worse when engine is warmed up put I can watch the
fuel pressure drop on the EIS and that's when It begins to stumble. Engine does
run on the hot side but never had this problems before. It just surfaced a few
weeks ago and seems have gotten worse.

Bruce



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I'm working firewall forward and have a question regarding fuel pumps. My O-320 came with an engine driven fuel pump, I removed it thinking gravity would give me plenty of pressure.
I had to pull the engine off to change out recalled ECI cylinders and the mechanic told me I should have left the fuel pump on. He felt it would give consistent pressure.
What are all you guys doing in the Rebel world? Pump or no pump.
Thanks
Randy R320



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