The car is an '86 GT 2.8 liter V6, that isn't really starting or running (see this post for more details: https://www.fiero.nl/forum/Forum2/HTML/125393.html. When I hook up a fuel pressure gauge on the test port and either jumper the "G" terminal on the ALDL or turn the key to on, the gauge goes to just over 40 psi, when I shut the fuel pump off it drops maybe 1 psi and stays there, even a half hour later. However, when I crank the engine the pressure drops to around 30 psi, note that the car is firing some but not starting. Is 30 psi too low for cranking fuel pressure? I checked fuel flow this morning by removing the fuel pipe from the discharge side of the fuel filter, putting a big hose over the nut end of the fuel filter and directing the other end of the hose to a pan and then running the fuel pump for a minute. I got about 3/4 of a gallon, which should be plenty of flow. I am wondering if the fuel pressure regulator is bad or an injector is stick open when I am cranking the engine. Note that the car was running great when it suddenly started coughing and sputtering and I have not yet been able to track the source of the problem.

30 should be OK. have you tried using starting fluid?

The pressure should pump up to 42.5 to 43.5 psi at ignition ON priming. Running pressure should be about 38 psi or better. 1 psi drop-off is very good. Check your MAP sensor for leaking or broken vacuum line to the pressure regulator. Also check the 2 fuses for the fuel injector. There's one for the front bank and one for the rear bank. They're labled inj 1 and inj 2.

Hey I'm having a similar problem with an 88 GT I have done the same fuel check 46psi and it drops to 41 or 42 the car was running Ok it had a bad vacum leak with that cheap metal tube from the EGR I replaced it. But the car just started running real rough I bareley made it home and I checked the fuel pressure to no avail then I replaced all of the electrical side plugs wires cap rotor coil ignition module chip and board no luck any ideas where to go next. I did find a code for the IAC number 35 replaced it and the code went away and the car started and ran real rough agian. The code is gone but it will not start now it sounds like it can but it just won't.

Welcome to the Forum!

Your problem deserves it's own thread......and then people can ask you questions.
For this thread, we will try to fix hzl6cm's car.

More info on this. Played around with timing, cranking etc. and had it firing, but not starting. Though, even after a half hour or so, the system was still at about 40 psi. Then I had my daughter run the key to crank it while I looked at the gauge, it actually stayed around 40 this time. The low readings earlier may have been due to the air in the lines after I drained them when I unhooked the pipe from the filter to check fuel flow. Yesterday, after playing around a lot with timing I did get the car to finally idle enough that I could get out and check timing, fuel pressure, etc. with it running. While idling the fuel pressure was at about 33 psi, but as soon as I blipped the throttle it went right up to 40 psi. Plus, this whole time that it has been barely running, the engine smoothly revs when I blip the throttle, it just doesn't want to run at a constant speed without coughing, sputtering and backfiring, so I don't think that I have a fuel issue, I'm leaning more towards that it must be the timing chain, so I will start a new thread on that since I don't want to swap out the timing chain and gears if it is some other ignition related item.

I don't know how familiar you are with Fieros, so I'm going to base my response upon the number of posts you've made as an indication.

When you set the timing, did you jumper the ALDL? You cannot effectively set the timing, otherwise.

If the car will run, start it and let it warm up, then turn off the engine and ignition switch. With ignition off, insert your jumper in the lower two terminals on the passenger side of the ALDL. Then you can turn on the ignition and start the engine to set the timing. Once it's set, turn off the engine and ignition switch and remove the jumper wire. Inserting the jumper with the ignition on could possibly damage the ECM or PROM.

Also, after you replaced the Idle Air Control switch, the car has to run for a while to allow it to readjust, so that could have caused some initial running problems at startup.

quote Originally posted by hzl6cm: When I hook up a fuel pressure gauge on the test port and either jumper the "G" terminal on the ALDL or turn the key to on, the gauge goes to just over 40 psi, when I shut the fuel pump off it drops maybe 1 psi and stays there, even a half hour later. However, when I crank the engine the pressure drops to around 30 psi ...

That is normal behavior, and it indicates that your fuel pump and fuel pressure regulator (FPR) are probably working properly. The Fiero FPR maintains a constant pressure differential between the fuel rail and intake manifold vacuum. That's what the vacuum connection to the FPR is for. Since your gauge measures pressure at the fuel rail with respect to ambient atmospheric pressure, what you see on the gauge will vary as manifold vacuum varies.

Per GM, "normal" fuel pressure on the gauge should be ~44 psig (3.0 bar) with the engine not running ... i.e. when manifold pressure = ambient ... and with the engine running the pressure indicated on the gauge should drop ~1/2 psi for every inch (in-Hg) of manifold vacuum.

[This message has been edited by Marvin McInnis (edited 01-21-2013).]