bbakerco Posted December 24, 2020 Report Posted December 24, 2020 Mooney Christmas everyone. In my 78 J, when I turn on my master (engine not running, boost pump off), my fuel pressure gauge goes up, hangs out a bit at mid point then pegs. Sometimes it comes back down for a bit, then pegs again. While engine is running and in flight, it's just pegged. I have a JPI 830 that shows fuel "flow" is fine but doesn't show pressure. Looking for wisdom as to whether it is likely the gauge or the transducer? Is this a airworthiness item? Transducer appears to be an 880045-501 which would be a pretty easy and inexpensive fix. The gauge, not so much. Thanks, Bryan Quote
Hank Posted December 24, 2020 Report Posted December 24, 2020 My first thought is the wire is grounded somewhere. 1 Quote
bbakerco Posted December 24, 2020 Author Report Posted December 24, 2020 5 minutes ago, Hank said: My first thought is the wire is grounded somewhere. I thought about that but thought if grounded, it would just go straight to pegged and not hang out in the middle for several seconds. If my oil pressure wire was grounded, it would peg immediately. But will check that for sure. Quote
ArtVandelay Posted December 24, 2020 Report Posted December 24, 2020 I thought about that but thought if grounded, it would just go straight to pegged and not hang out in the middle for several seconds. If my oil pressure wire was grounded, it would peg immediately. But will check that for sure.It would affect all the gauges in your 6x1. If just 1 gauge has problems I would lean towards sensor problem. I’d also consider if now would be a good time to go to the 900. Tom Quote
Hank Posted December 24, 2020 Report Posted December 24, 2020 18 minutes ago, ArtVandelay said: It would affect all the gauges in your 6x1. If just 1 gauge has problems I would lean towards sensor problem. Just my Oil T pegged once, when the safety wire on my oil filter shifted. It's worth checking into before spendung big bucks, which wouldn't have fixed my problem of oil filter safety wire touching the Oil Temp sensor. Quote
carusoam Posted December 25, 2020 Report Posted December 25, 2020 Usual gauge failures typically go one way or the other depending on wether they are getting full voltage or zero voltage... Something else may be delivering voltage near its ground... this causes wacky readings... Fortuantely you won’t need to run the engine to go hunting for the cause... Are you handy with a volt meter? Our OilP gauges can be pretty complex sometimes... a small computer on a board... inside the pressure sensor housing... so look up what OilP sensor you have while you are in there... we have done a lot of reading on similar challenges with Bravos around here... PP thoughts only, not a mechanic... Best regards, -a- Quote
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