Fuel Pressure M20J

[andrem]

Hello all,

 

my J's fuel pressure reading (green arc is 14 to 29) shows the following symptoms:

with electric pump off:

 - in flight, at altitude, steady below the green arc

 - taxiing, steady inside the green arc

 - when recovering from a stall without the electric pump on, she hesitates and the fuel pressure drops.

 - at low power settings, varies between just below and just inside the green arc

 - at higher power settings, below the green arc 

 

with electric pump on:

- always close to top of the green arc.

 

I am not due for an MPI for a few months and there is no Mooney AMO close by.

 

Does it sound like the engine driven fuel pump is not producing enough pressure?

 

She has 1170 TSN on engine, prop and airframe, since 1977.

[N201MKTurbo]

Either your fuel pump is bad or you have an air leak between your electric pump and your mechanical pump.

Either way, it is a serious problem that needs to be resolved.

If you have an air leak it will be a fuel leak with the boost pump on. Set the mixture to idle cutoff turn on the boost pump and look for fuel leaks at the lower left cowl and the boost pump cover plate. Also check the fuel pump drain lines. Both the mechanical and electric. If the diaphragm has a hole in it it will leak from the drain line with the boost pump on.

[andrem]

Thanks N201MKTurbo. 

 

Not sure of its related, but I've lost some oil lately as well, with a leak somewhere very close (probably above) the oil filter, as far as I can see.

 

I have not smelt fuel, but I'll try the pump on with mixture to idle cutoff and see what can be seen.

[andrem]

Changed AMO's and the problem was solved fairly quickly - the mechanical fuel pump gasket was "loose" which led to oil leakage and low fuel pressure. I've flown 3,5 hours since then and no bad symptoms  - just quick fun.

 

I don't want to know how that happened within a few hours of having my 6 monthly oil change done.

[M016576]

Glad it was resolved safely, and thanks for posting your followup!