Fuel Pressure Problem
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Intermediate
Joined: Aug 2005
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From: ROSEDALE VIRGINIA
Fuel Pressure Problem
I have a 92 6-speed with a paxton S/C and blowerworks superfueler / macrofueler. Lately the fuel pressure has went has high as 110 psi before I could stop the car. Pressure is typically 45-50 psi. It starts climbing after 5 minutes of driving and hits 70 or higher after 10 -15 minutes and as high as 100 psi after 20 minutes. Any suggestions on what to check as the problem?
Melting Slicks
Joined: Jun 1999
Posts: 2,872
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From: Wilmington NC
If it is still running, it can only be one of two things, the regulator possibly but my bet would be on the superfueler, need to make sure all lines going to it, ie vacuum boost reference are clean and likely need to check the diaphrams and make sure they are not torn or damaged.
Chris
Chris
Melting Slicks
Joined: Dec 2000
Posts: 2,719
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From: Fremont Oh
Originally Posted by moose932
I have a 92 6-speed with a paxton S/C and blowerworks superfueler / macrofueler. Lately the fuel pressure has went has high as 110 psi before I could stop the car. Pressure is typically 45-50 psi. It starts climbing after 5 minutes of driving and hits 70 or higher after 10 -15 minutes and as high as 100 psi after 20 minutes. Any suggestions on what to check as the problem?
Moose does it have a pressure switch? It is possible the pressure switch may have gone bad on the superfueler... Also are you sure the dip switches are set correctly? It sounds like it could be the settings are "off "... f i recall itworks similat to the superpumper, where the additional 3 injectors kick in at a particular boost setting.... I',\m not sure if it also has the return solinoid like the superpumper has ( which is what I have)...
Just a thought...
Mo
Supporting Vendor
Joined: Oct 2004
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S/F vs. S/P
Moose - The Superfueler is an A.I.C. controller and as such has no effect on fuel pressure other than to consume fuel when injecting.
Mo, the S/F has no return line solenoid like the S/P. The S/F simply taps off the GM fuel pressure test port for fuel to the additional injectors.
Moose, you must troubleshoot your abnormally high fuel pressure just like a stock Vette. Either your fuel rail regulator or fuel return line to tank is at fault. If you don't have proper tools and knowledge you must be careful because opening up the return line, even with the engine off, can cause fuel to spray everywhere.
At the engine fuel rail you have a supply & return S/S braided lines with quick connects. The return line is the smaller of the two (5/16" vs. 3/8"). With the engine off, and the pressure relieved, disconnect the return line at the rail. This requires an inexpensive tool available any auto store. Buy yourself a roll of 5/16" fuel line - doesn't have to be rated for high pressure which is quite expensive - carb style line is just fine. Clamp the hose to the fuel rail return (be sure it is secure or you'll burn your car down). Run the line over the floor to the rear of the car and push some of the hose in thru the filler cap being sure it can't flop out. Now start the engine and monitor fuel pressure. Observe the hose at start-up at rear of car - pull the hose out of the tank and see the "healthy" flow keeping the hose aimed into the tank obviously. After 20 minutes or so if the fuel pressure remains normal then the fault is in the return line - somewhere swelling and restricting the return. However, at any point in time, if the fuel pressure starts to rise, then the fault is at the regulator and it must be repalced.
Regards
Greg
Mo, the S/F has no return line solenoid like the S/P. The S/F simply taps off the GM fuel pressure test port for fuel to the additional injectors.
Moose, you must troubleshoot your abnormally high fuel pressure just like a stock Vette. Either your fuel rail regulator or fuel return line to tank is at fault. If you don't have proper tools and knowledge you must be careful because opening up the return line, even with the engine off, can cause fuel to spray everywhere.
At the engine fuel rail you have a supply & return S/S braided lines with quick connects. The return line is the smaller of the two (5/16" vs. 3/8"). With the engine off, and the pressure relieved, disconnect the return line at the rail. This requires an inexpensive tool available any auto store. Buy yourself a roll of 5/16" fuel line - doesn't have to be rated for high pressure which is quite expensive - carb style line is just fine. Clamp the hose to the fuel rail return (be sure it is secure or you'll burn your car down). Run the line over the floor to the rear of the car and push some of the hose in thru the filler cap being sure it can't flop out. Now start the engine and monitor fuel pressure. Observe the hose at start-up at rear of car - pull the hose out of the tank and see the "healthy" flow keeping the hose aimed into the tank obviously. After 20 minutes or so if the fuel pressure remains normal then the fault is in the return line - somewhere swelling and restricting the return. However, at any point in time, if the fuel pressure starts to rise, then the fault is at the regulator and it must be repalced.
Regards
Greg
Melting Slicks
Joined: Apr 2000
Posts: 2,793
Likes: 46
From: Elizabeth City, NC
Don't rule out a bad fuel pressure gauge either. Maybe the sending unit is going out. Check your pressure with a mechanical gauge from the factory test port to see if it matches what your other gauge was telling you.
