I've noticed over the last couple of days while just driving that my fuel pressure has been off. I have a pressure gauge inside the vehicle and a Holley AFPR. Normally at idle the car sits at 43 and during acceleration it goes up to around 47ish. While at idle this morning after first start, the pressure dropped down to 34 which it has never done since the new regulator. During normal acceleration, the pressure actually dropped while the engine RPM went up. The car has about 130k on it, engine rebuilt about 8k ago, and to my knowledge still has a stock fuel pump. Could this be signs of the fuel pump going bad or a vacuum leak to the regulator?

Could this also cause my engine to run hot? Just driving in the city I noticed my temp gauge climb to almost the red. I have a low temp thermostat and fans to turn on at about 180. The fans were running, the A/C was off, and the radiator is full of coolant and flowing. I didn't know if the lack of pressure makes it run lean and thus heating up the engine.

I plan on supercharging the engine next month and the kit includes an inline pump and definately don't need a fuel dropoff....kaboom.

 

when you prime the key does the pressure hold or drop? sounds like a pump starting to go and it;s just too weak. that would cause a lean condition.. and if it;s more then can be compinsated for lean=hot and also =kaboom especialy with boost

 

It will climb to about 43 when the key is turned but will drop off a little shortly after. I didn't know if the fuel pump just flat out dies or if some gradually fail.

 

Hmmm.....mine is doing the same thing.......I wonder if this could be my hesitation issue.....

Thinking about it, the FRP is based on vaccuum. No vaccuum = highest pressure. Idle would be about your lowest pressure theoretically speaking. As the throttle blades open, vaccuum goes down as map comes up, and pressure should come up in conjunction.........Unless I'm thinking **** backwards.

 

No I think you are right on track. Since the regulator is pretty new and the stock pump probably has never been replaced, it narrows it down to the pump a lot. Anyone have any good checks to do or experiences with anything similar happening?

 

anyone?

 

I think i may be having a similar problem.

1. I have a miss at half tank. Not at full, just a 3/4 to 1/4. Under 1/4 it actually seems to go away as well...strange...

2. Its been running warm. Usually it sits right at 180 (thermostat) but lately its been climbing to half, even with the high speed fans on. With AC on it will overheat.

3. I failed smog for high NOX. Which is caused by high combustion temps i believe.


I think its my fuel pump going out. I haven't got a chance to check fuel pressure yet though. Let me know if you find out anything.