High fuel pressure

[David Mazer]

Awhile ago we installed a JPI 900 in a 74 M20F.  Since then we regularly get a high fuel pressure warning with pressures as high as 44 PSI.  The warnings last for a few seconds to a few minutes,comes and goes for extended periods (hours), and happens at various stages of flight but doesn't seem to be related to a cold start or to start or high OAT or less high OAT (we are in Florida so it really never gets too cold) or altitude or power settings or anything I can determine. The engine continues to run smoothly and without power loss or surging.  I've never noticed the fuel pressure to be low.  The boost pump is off. The JPI's fuel pressure range is pre-set at JPI for Mooney standards.

Anybody seen this before and found a solution? Thanks for your advice.

[carusoam]

David,

There have been a couple issues related to stability of pressure readings related to JPI methodology...

MP and FP have usually been more difficult to get a steady reading on.  

But, that was steadiness...  Your issue is exceeding a limit for an unknown reason... Could be different.

for an example....

Good luck with finding you gremlin.

Best regards,

-a-

[Marauder]

2 hours ago, David Mazer said:

Awhile ago we installed a JPI 900 in a 74 M20F.  Since then we regularly get a high fuel pressure warning with pressures as high as 44 PSI.  The warnings last for a few seconds to a few minutes,comes and goes for extended periods (hours), and happens at various stages of flight but doesn't seem to be related to a cold start or to start or high OAT or less high OAT (we are in Florida so it really never gets too cold) or altitude or power settings or anything I can determine. The engine continues to run smoothly and without power loss or surging.  I've never noticed the fuel pressure to be low.  The boost pump is off. The JPI's fuel pressure range is pre-set at JPI for Mooney standards.

Anybody seen this before and found a solution? Thanks for your advice.

David -- I have a 900 installed in my 75F and I have not seen it do this. I have two fuel pressure gauges (an EI FP-5L and the JPI 900) in my plane and then match within a 1/2 PSI of each other. I would call JPI and get their opinion. I suspect it is instrumentation and not an actual pressure problem.

[N601RX]

Does the ground wire for the unit run out to the engine? Is the sensor mounted to the firewall and not directly to the engine or baffling? 

I had some problems with my fue pressure originally after installing my 900 and found out that the fuel pressure is not a steady 25 like the gauge shows it to be. It pulses as the engine rotates.  The pulses seem to vary from a little above 10 to up onto the high 30's with the 25 displayed on the mechanical gauge being the average. 

[David Mazer]

Thanks to all for your responses.

 

We also had the manifold pressure issue and the unit needed to be returned to JPI for a fix.  We have contacted them about the fuel pressure but may need to again.  I don't know how the sensor is mounted or ground wire is run.  What would be the differences and which should it be?