Inconsistent Fuel pressure
10-29-2006, 07:24 PM
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Car: 89 IROC
Engine: 350 CI Tuned Port
Transmission: Automatic
Axle/Gears: 3:45
Inconsistent Fuel pressure
Since installing a fuel pressure gauge I have noticed that my fuel pressure runs 5-10 lbs higher when the vehicle is cold than when it is warm. It needs to run about 1/2 hour and get good and warm under the hood until it gradually falls to where I want it. I am running a modified stock regulator. Is this a normal situation or not?
Thanks
Roy
Thanks
Roy
10-30-2006, 07:16 AM
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Car: check
Engine: check
Transmission: check
If the fuel pressure gauge is liquid filled and under the hood, the issue is with the gauge. Liquid filled gauges are only accurate at room temperature. That is unless vented, which usually isn't done.
RBob.
RBob.
10-30-2006, 07:27 AM
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Car: 89 IROC
Engine: 350 CI Tuned Port
Transmission: Automatic
Axle/Gears: 3:45
Rbob,
The Fuel pressure gauge is a basic autometer (I think it was arond $50) and is mounted on the hood at the back. It doesnt appear to be liquid filled to me.
Roy
The Fuel pressure gauge is a basic autometer (I think it was arond $50) and is mounted on the hood at the back. It doesnt appear to be liquid filled to me.
Roy
10-30-2006, 01:09 PM
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Car: check
Engine: check
Transmission: check
Look for a rubber plug on the gauge housing. That it s tip off that it may be liquid filled.
If it isn't liquid filled, then yes, I'd say there may be an issue with the fuel pressure. A stock setup has the FPR vacuum referenced. This will cause the fuel pressure to change in relation to the manifold vacuum. Remove the vac line from the FPR and plug the line. Then read the fuel pressure. This should be done with both a hot & cold engine.
With the vac line unplugged the fuel pressure should not change between the 2 engine temperatures.
RBob.
If it isn't liquid filled, then yes, I'd say there may be an issue with the fuel pressure. A stock setup has the FPR vacuum referenced. This will cause the fuel pressure to change in relation to the manifold vacuum. Remove the vac line from the FPR and plug the line. Then read the fuel pressure. This should be done with both a hot & cold engine.
With the vac line unplugged the fuel pressure should not change between the 2 engine temperatures.
RBob.
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