Fuel Pressure Question.

Ryan A Harris

Registered User
Can anyone tell me the correct pressure for idle on the SC's. From what I've read, by pulling off the vaccum line on fuel pressure regulator, this will simulate W.O.T. At W.O.T what should the pressure be. I've heard and read a few different pionts on this topic. A mechanic I was talking to, was telling me the pressure should increase up 10 pounds and W.O.T. But then I've read here(somewhere) that for every pound of boost, the pressure will increase 10 pounds. So then at 15 PSI, I would be making an extra 150 PSI in the fuel lines? Is that right?

I'm also looking to add a fuel pressure gauge to the car now. I'm not looking for the under the hood mounting style either. Does anyone have a set up for fuel pressure in the passenger compartment? I think I remeber that Dave Niebert has a set up like that?

Any help would be great Thanks guys.
 
I think factory pressure is 39 psi. You are correct at removing vaccum line to adjust. But it adjusts directly, pound for pound on fuel pressure as boost goes up, 10 psi of boost = 10 psi of fuel pressure. It does it to compensate for the added pressure in the system so the proper amount of fuel can be injected.
 
Ok cool. I was wondering if that was "fishy", seemed like a large amount of pressure in those lines. That helps out, thanks.
 
...

hey i got a electrical fuel pressure gauge, mounted in a custom front dash piece, i took off the shrader valve and put the sendor there with a 45 degree angle and extention i believe...mechanical gauges you have to run it with a fuel line and it is cant be runned inside a car legally thats why i went with all electrical gauges... Alex LaChance

AutoMeter Pro-Comp Ultra Lite (All Electrical) Gauges Below

1 - 5" Tach w/Small Shift Light
2 - 5" Speedo (Programmable)
3 - Water Temp Gauge
4 - Meter Pro-Comp Ultra Lite (Electrical) Oil Pressure Gauge
5 - Fuel Pressure Gauge
6 - Boost Pressure Gauge
7 - Nitrous Gauge
8 - Air/Fuel Gauge
9 - Air/Fuel Gauge
10 - Fuel Level Gauge
11 - Volts Gauge

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The stock fuel pressure is 39.508 PSI or 2.7 bar. That would be what you should have +/- the tolerance of the regulator with the sense line off. At idle the pressure will depend on the vac. you pull. The more vac. the lower the pressure. Nomila abnout 30-35 PSI. As you go into boost pressure rises at a 1:1 ratio so at 10 PSI boost you should be around 49.5 PSI of fuel pressure.
 
Ryan,
Are you still trying to find out why your car is Pig rich?
what I plan to do is next time at the dyno I was put my fuel pressure gauge on and see what the reading is so maybe you want to do the same.

Dave,
Thats a cool gauge you have just woundering how much you paid for it I just look and it's $420 in Canada :(
 
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Ryan,

That's the correct post...here is a picture of the fuel pressure gauge #3363.

atm-3363.jpg


Jason,

I bought it from Summitt about 1-1/2 years ago for around $267.

David
 
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Dave, it doesn't seem to work for me. I cam alsways just do a search for your posted.

Yes Jason, I am still looking into this problem I am having. Dyno tune will be soon, have lots to test out. I do want to check what the pressure is, maybe a related problem to the fuel pump, filter, or injector, plus it could even be the F.P.R. Or the fact that I have the older style SC on the car too, may not be moving enough air for the stock '95 injectors. I have #42's(injectors) to go in, but running rich, so that may not be best to do, yet. No tuner, so this must be a mechanical problem. Still running stock MAF, so this leads my to think that if its not the SC, then its fuel related.
 
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