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Fuel Pressure WAY high and MAP sensor voltage too low.
I'm pretty sure I am having high fuel pressure issues. I read the service manual last night and it says that FP at key on should be 41-47PSI. At idle it should drop to 3-10PSI. My car is getting to about 45PSI at key on but I know it has never dropped after the car starts (or at least for the past 20K miles because I have a gauge hooked up to an electronic fuel pressure sending unit off of the rail). For the past 1000 miles or so, the FP goes WAY high (>100PSI) when under throttle. I'm thinking I may have a fuel return blockage or something and I probably won't have time to investigate for another couple weeks. Another issue, that I think may be related is, I'm getting an intermittent MAP Sensor signal voltage too low (pressure too high). My vacuum seems to be pretty steady when running and drops when the throttle is goosed. It appears that the FP is regulated by vacuum which is why I'm thinking maybe the two are related. I'm not sure how Manifold absolute pressure and vacuum play together.
The funny thing is, the car seems to run OK even with high FP. I'm looking for comments/suggestions. THANKS!!
95 Trans Am 175K LT-1 160°stat, Hypertech Tune, K&N,gauge pod(FP,A/F,Vacuum), Gen 4 taillights
99 Durango 5.2L 156K
91 Ford Taurus SHO Stage 2 158K
97 FZR600 K&N, Wheelie gears 22K
96 Taurus Wagon 178K
Last edited by jkichline; 05-20-2009 at 07:04 AM..
Reason: Can't spell... :)