trouble shooting fuel pressure gauge problem
11-06-2008, 05:47 PM
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trouble shooting fuel pressure gauge problem well, after replacing pump and regulator, found out that my fuel pressure problem is in the gauge (checked by replacing with underhood gauge.
The gauge is an autometer C2 gague. It shows that idle pressure is about 6psi lower than the under hood gauge (56 vs 62-which is what it showed when the gauge and fuel pump were first installed 3yrs ago). It has gradually, over the last three years, started showing lower fuel pressure at idle and cruise (that's why I thought it was the pump). The other thing it does is that anytime the throttle is pushed, the gauge shows a drop in pressure, EVEN IN NEUTRAL. It's worse at WOT with the reading dropping down to 48psi.
This made me think electrical so I check what I traced to be the ground wire. Seemed fine (bolted underneath steering wheel). I even unbolted it and sand papered a bit to get a better contact. I checked it using a voltmeter and the ground showed 11.8V key on, engine off. Compared this to the ground for my radar detector and was withing less than 0.05V.
I guess my question is if there is a way to figure out if it's the gauge or the sending unit? The sending unit is apparently 2/3 the cost of a new gauge w/SU so I'm debating if I should just buy the unit.
Thanks for any help!
The gauge is an autometer C2 gague. It shows that idle pressure is about 6psi lower than the under hood gauge (56 vs 62-which is what it showed when the gauge and fuel pump were first installed 3yrs ago). It has gradually, over the last three years, started showing lower fuel pressure at idle and cruise (that's why I thought it was the pump). The other thing it does is that anytime the throttle is pushed, the gauge shows a drop in pressure, EVEN IN NEUTRAL. It's worse at WOT with the reading dropping down to 48psi.
This made me think electrical so I check what I traced to be the ground wire. Seemed fine (bolted underneath steering wheel). I even unbolted it and sand papered a bit to get a better contact. I checked it using a voltmeter and the ground showed 11.8V key on, engine off. Compared this to the ground for my radar detector and was withing less than 0.05V.
I guess my question is if there is a way to figure out if it's the gauge or the sending unit? The sending unit is apparently 2/3 the cost of a new gauge w/SU so I'm debating if I should just buy the unit.
Thanks for any help!
