Cabo Lee Posted October 31, 2016 Report Posted October 31, 2016 (edited) My 1966 M20E is showing no fuel pressure on the MF/FP gauge. It shows no pressure with the boost pump on. The engine is running well during run-up and I can hear the electric fuel boost pump when turned on. I have sent the MF/FP gauge out for repair and after overhaul no fuel pressure. Any suggestions on possible problem with the MF/FP gauge. Edited October 31, 2016 by Cabo Lee correction Quote
Guest Posted October 31, 2016 Report Posted October 31, 2016 It could be the restrictor fitting in the fuel injection servo is blocked. The fitting is on the back side of the servo, up against the oil sump. If you take the hose off at the firewall and turn on the pump you can confirm if there is any fuel flow through the fitting and hose. Following the hose back to the servo will help you locate the restrictor fitting. Clarence Quote
carusoam Posted October 31, 2016 Report Posted October 31, 2016 Clarence is a highly esteemed mechanical guru... I am attempting to add some detail to his post. Not sure if I have it right though... yesterday I had the opportunity to post some details from a mid 60’s MM that had a note regarding restrictors used with the FP gauges themselves... I posted a drawing's number from the maintence manual. There are two types of restrictions that Mooney used. One for the FI'd engine and the other for the carbed engine. Very Different pressure ranges. The gauge's restrictor is called a 'snubber'. The job of the snubber is a tiny hole that provides a calibrated resistance for the gauge. The fuel pressure gauge is seeing a lot of noisy peaks in it's days to day activities. The snubber eliminates the peaks to give a smooth, useable, reading for the pilot to use. According to the manual the snubber is a part. A part can probably be removed and cleaned. The thread I wrote... See if that is helpful. The oddity of the drawing is, It is separated from the instruments section... I am an ordinary private pilot, not a mechanic... Best regards, -a- Quote
Cabo Lee Posted October 31, 2016 Author Report Posted October 31, 2016 Thanks, for the input on the snubber / restricter valve on the MF/FP gauge. I was able to order one with that information from Lasar. According to Lasar, this a common problem. I will clean my old one and keep it as a spare. Thanks again. 1 Quote
C-FRJI Posted May 12, 2018 Report Posted May 12, 2018 I went to one of these. Price is Canadian dollars...don’t panic. also a bit cheaper on line from the factory. Quote
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