Fuel Pressure Regulator
03-13-2005, 05:48 AM
#1
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Fuel Pressure Regulator
My 94 GTS is running quite rich and produces smoke on start up. I think the fuel pressure regulator needs to be changed:
1) What are the sign of a bad regulator ?
2) I have been told that this speed demon requires 2 regulators ? is that correct ? are both the same part or different parts ? (only found 1 under the hood)
Would appreciate the advise. Moe
1) What are the sign of a bad regulator ?
2) I have been told that this speed demon requires 2 regulators ? is that correct ? are both the same part or different parts ? (only found 1 under the hood)
Would appreciate the advise. Moe
03-13-2005, 06:25 AM
#2
Rennlist Member
If you suspect fuel pressure, installing a pressure gauge might be the most informative ( and economical) first step. One other failure mode of pressure regulators and dampners ( three in total) is a diaphram that bypasses fuel into the vacuum system - pull vac. hoses to check.
Rich operation is frequently due to malfunction of the Temp II sensor (multimeter to check), the MAF, and/or the LH ECU: for the latter two, is there another 928 nearby that will allow units to be exchanged for a trial?
Rich operation is frequently due to malfunction of the Temp II sensor (multimeter to check), the MAF, and/or the LH ECU: for the latter two, is there another 928 nearby that will allow units to be exchanged for a trial?
03-13-2005, 06:52 AM
#3
Rennlist Member
Hi Moe,
Does it just rum rich on start up, and then OK ? If so, then you may have a leaking injector.
If it runs rich all the time, then follow suggestions by Garth.
Your GTS has one pressure regulator and 2 fuel dampers.
Does it just rum rich on start up, and then OK ? If so, then you may have a leaking injector.
If it runs rich all the time, then follow suggestions by Garth.
Your GTS has one pressure regulator and 2 fuel dampers.
03-13-2005, 11:05 AM
#4
Rennlist Member
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1) Pull the vacuum lines from each regulator and dampener, and check for any trace of fuel in the line (rub the end of the line on your finger, and smell your finger). If there is any fuel in the line, replace that unit.
2) If there is no fuel in the lines, crank the engine under the conditions where it runs rich. Rev it up a couple of times, but don't run it more than thirty seconds. Shut it down and restart. If the engine still runs rich on the second start, check the Temp II sensor. If it doesn't run rich on the second start, run a couple of bottles of Techron (the real stuff, at $6 a bottle, not the cheap stuff) through the tank to see if an injector is leaking.
2) If there is no fuel in the lines, crank the engine under the conditions where it runs rich. Rev it up a couple of times, but don't run it more than thirty seconds. Shut it down and restart. If the engine still runs rich on the second start, check the Temp II sensor. If it doesn't run rich on the second start, run a couple of bottles of Techron (the real stuff, at $6 a bottle, not the cheap stuff) through the tank to see if an injector is leaking.
03-14-2005, 01:40 AM
#6
Three Wheelin'
I bought a used FPR, and when I installed it, my fuel pressure went to over 99psi on my gauge. I attribute it to varnish on the FPR which jammed it in a closed position. If your car has sat for any extended periods, it may be a similar condition. I guess you can run down the easier tests first. The FPR should be relatively easy and cheap to swap out, if that's the problem.
