Issue with Fuel Pressure, keeps changing at idle....

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03-29-2004, 05:13 AM

BigDogJonx

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Issue with Fuel Pressure, keeps changing at idle....

Well let me lay out what I seem to be noticing.

Lets say its about 35F outside. I set my SARD so my base idle FP is about 34psi.

Now lets say ive been driving the car for 4hrs. If I come to a stop and let it idle or even on the highway in N, my base idle is now almost 26psi.

Ok, so now I pull into my garage, car still running, set it back to 34psi on the base idle again on the SARD FPR.

Then come back say after 5hrs to drive the car after it has fully cooled down, and now the base idle is about 40psi.

This is confusing the hell out of me. Makes me think the fuel temps are affecting this. Like when the temp is nice and cold and the fuel is cold. But at this point I got no clue what the deal is.

BTW, Ive got the SARD FPR, Cartech FMU (not really being used, set to 1:1 ratio at the moment) and the Walbro GSS342 in the tank.

Dixit

03-29-2004, 05:34 AM

Stephen Max

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Voltage fluctuations to the fuel pump? Maybe your alternator is putting out less voltage when it gets hot.

I'd be inclined to set the fuel pressure so that you get at least 34 psi minimum and just live with the higher fuel pressure at other times, until you get the problem sorted out.

03-29-2004, 05:56 AM

BigDogJonx

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Well Im normally mointoring the the voltage through my turbotimer and its almost always around 13.8-14.1V

I guess I will take a look at it a bit more. I was thinking it could be the SARD fpr having issues.

Thanks Stephen.

Dixit

03-29-2004, 08:16 AM

[maxi-overdose]

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Quote:

Originally Posted by BigDogJonx

I would unplug the vacuum hose to the SARD fpr and drive around to eliminate the FPR as the cause.

03-30-2004, 12:11 PM

1MAX2NV

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My AEM FPR does the same thing. It would be 3 psi difference when the car is totally warmed up. I never had a gauge on the oem setup so I don't know if OEM fpr does the same thing.

03-30-2004, 12:44 PM

BigDogJonx

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Well when I had my OEM fpr, never saw this issue. I had the FPgauge on there for about 6months before switching over to the Sard. It ****es me off cause everytime this happens it throws me a/f off and I have to retune with my wideband.

I got a feeling has to be the heat from the turbo and piping. Im going to test this theory by putting a heatshield near the FPR. Because I know when I touched the fuel line (braided) it was hot. Definetely cant hold it solid.

Dixit