High fuel pressure and warning light

[J0nathan225]

JPI 450 and g2, no Fuel P on those. 

[Marauder]

28 minutes ago, J0nathan225 said:

JPI 450 and g2, no Fuel P on those. 

I would highly suspect that your gauge is the problem and not your fuel pressure itself. I would try to find gauge to verify your FP reading. Perhaps someone has one available from an engine monitor upgrade. If you aren't planning on a full engine monitor yourself, perhaps something like an FP-5L will give you another option.

[J0nathan225]

I believe the MP/FP was O/H'd in the '15 or '16, could it be the transducer?

[Marauder]

1 minute ago, J0nathan225 said:

I believe the MP/FP was O/H'd in the '15 or '16, could it be the transducer?

Maybe. I would look in the logs to see what was done in 15 or 16. If the gauge was pulled and overhauled, what exactly did they do? They may have worked on the MP and not the FP side. The transducer could also have gone bad since the overhaul.

[Hillard]

Jonathan,

I fitted an factory overhaul IO360-A3B6 engine to my J model in November 2017 and found that the fuel pressure was running at 30-35psi.  Lycoming had supplied a different and supposedly “equivalent” fuel pump.  Apparently this different pump runs 30-35psi.  My A&P would not sign it out as the factory sets the pressure limit to 30psi.  The engine importer paid to supply and fit a new fuel pump with the old part number and it now runs at 22-25psi.

Apparently the higher fuel pressure should work just fine with the engine - but it does not conform to the airframe manufacturer limitations so it is not legal.  

[J0nathan225]

I have 62B26931 p/n. The one review on spruce references it pushing more than the mooney allowed 30psi too. 

[carusoam]

J0n,

there are a couple of threads around here related to new fuel pumps supplied by Lycoming that don’t meet the Mooney spec... are you familiar with those experiences?

Good news, you are not alone...

Other good news... There are solutions other people have used...

Crummy news... the added pressure is probably real, unless something has changed recently...?

 

Anyone know why there is a fuel pressure redline where it is?

I would suspect that something in the fuel system gets sensitive to higher pressures.... diaphragms, seals, and other soft parts in the fuel system....

PP thoughts only, not a mechanic...

Best regards,

-a-

[J0nathan225]

7 hours ago, Hillard said:

Jonathan,

I fitted an factory overhaul IO360-A3B6 engine to my J model in November 2017 and found that the fuel pressure was running at 30-35psi.  Lycoming had supplied a different and supposedly “equivalent” fuel pump.  Apparently this different pump runs 30-35psi.  My A&P would not sign it out as the factory sets the pressure limit to 30psi.  The engine importer paid to supply and fit a new fuel pump with the old part number and it now runs at 22-25psi.

Apparently the higher fuel pressure should work just fine with the engine - but it does not conform to the airframe manufacturer limitations so it is not legal.  

Yea I was reading one post about it earlier, which lead me to look up my P/N and it appears I have the newer pump. My MP/FP gauge was OH'd in early 2016, so I don't think that is the issue. Its very constant at 32-34, before crank my newly O/H'd boost pump takes the PSI to 28 then the engine driven takes over once started and drives it up some 32-34. I may look to see about having someone test the pressure inline before doing anything else. 

I'm about to start my IFR airplane add on and don't want the instructor or anyone else to have a major issue with it, is my biggest concern. 

Not overly excited to put money into another part, when this has worked for the last 30+ hours with me and I have had 0 issues other than a few PSI high. Lycoming rates the engine up to 45 PSI i believe. 

Edited July 24, 2018 by J0nathan225
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[LarryAZ]

Fascinating thread, but some odd solutions proposed.   M20C- fuel pressure on the engine pump climbed periodically to 6.2-6.2psi causing an EDM-900 alarm.  The first thing you should check is the finger screen in the carburetor.  It is a very short run from the engine fuel pump to the carb and that is the most likely culprit.  I' pulled my screen out Saturday and it was clogged with a find grain, white grit and what looked like tiny bits of plant material.  Cleaned it and FP now runs about 4.0-4.5.  Go to the simplest potential cause first.