What can cause my fuel pressure to lower under acceleration??
07-23-2009, 05:15 PM
#1
TECH Junkie
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What can cause my fuel pressure to lower under acceleration?? I got my fuel pump/fuel filter/fuel pressure regulator changed at a shop a few wks ago, and I noticed that when I accelerate, that the fuel pressure is lowering(Via Autometer fuel pressure gauge in my gauge pod). I dropped it back off at the shop, and they said they hooked up a fuel pressure gauge and drove around and that the fuel pressure raised under acceleration...
So he said maybe my gauge is bad, or my fuel sending unit is bad.
But it all sounds a little shady to me... do you guys have any ideas?\\
Thanks
Patrick.
So he said maybe my gauge is bad, or my fuel sending unit is bad.
But it all sounds a little shady to me... do you guys have any ideas?\\
Thanks
Patrick.
??? 
07-25-2009, 10:13 AM
#6
If you really trusted your shop you would not be second guessing them here?
I only do about 200 custom pumps/fuel systems a year so my posts are based on what I know...
Running an aftermarket pump with no hot wire kit is not exactly good, you should have one at your power level.
If you bought a generic kit with a rubber hose in the tank you will eventually have problems.
If you make 550rwhp, you are getting very close to the limits of what 1 pump can provide. I see you are basically there....
The pressure should only raise when transitioninig from part to full throttle. It should immediately go to approx 43-45psi & stay there. It wil not rise further after it hits full throttle unless you have a supercharger you are not telling us about. You can check this pressure by removing the vacuum line from the regulator with it idling. This is the pressure it should have at any rpm at full throttle or you have a supply issue.
The pressure drop (after fulll throttle) that goes down as rpm increases is typically due to insufficient fuel pump capacity as LT1 cars have the regulator on the rail.
I only do about 200 custom pumps/fuel systems a year so my posts are based on what I know...
Running an aftermarket pump with no hot wire kit is not exactly good, you should have one at your power level.
If you bought a generic kit with a rubber hose in the tank you will eventually have problems.
If you make 550rwhp, you are getting very close to the limits of what 1 pump can provide. I see you are basically there....
The pressure should only raise when transitioninig from part to full throttle. It should immediately go to approx 43-45psi & stay there. It wil not rise further after it hits full throttle unless you have a supercharger you are not telling us about. You can check this pressure by removing the vacuum line from the regulator with it idling. This is the pressure it should have at any rpm at full throttle or you have a supply issue.
The pressure drop (after fulll throttle) that goes down as rpm increases is typically due to insufficient fuel pump capacity as LT1 cars have the regulator on the rail.
08-12-2009, 10:47 PM
#7
Fuel pressure should not drop. If it is dropping below 59lbs, there is an issue. Stock is 59lbs. The only time you should see more is if you are using a boost reference regulator.
