84 Fiero won't start

[Protoclown]

I have a 1984 Pontiac Fiero with the 4 cyl engine and 4 speed manual transmission. The car has an unknown number of miles on it, but it is believed to be 100,000+. When the Fiero was parked 5 years ago, it was running rough. When we started to get it back into roadworthy shape a few weeks ago, we dropped the fuel tank, cleaned it out, purged the fuel line, installed a new fuel pump, a new fuel filter (with the flow in the correct direction), and put in new gas, with fuel injector cleaner. After all this, the car fired right up, and ran very well, to our surprise. It started every time after that and ran great for a couple of weeks. One night after repairing other things, I drove it up to a parking spot, and shut it off. The next week, I tried to start it and all I got was about one or two seconds of it firing to life and that was it. It did that a couple more times and then no firing at all. We got it into the shop and began to diagnose the problem. We noticed that when we tried to start the car, the TBI would spray for a second, then drip. There was plenty of gas in it, but to be sure, we added more. We cleaned the TBI and tried again. Same results. We realized there was no pressure to the TBI. We checked all the fuses, and tried to check the fusible links, but we were lost in this area, partly because there were some wiring problems that had to be repaired around the battery (which the car still ran great after the wiring repairs), so we aren’t sure if the fusible link to the starter was rewired, or if we bypassed it, but the wires “seem” solid. We changed the fuel pump relay and the oil pressure switch. We checked the codes from the ECM, and there were none. After all this, here’s what the car is doing: When you turn the key after the car has been sitting for a short time, you might hear the fuel pump cycle for two seconds, or you might not. If you do, it usually fires for a second, then quits, but it won’t continue to run. It is very intermittent, but we are fairly sure the main issue is the fuel pump is not getting the signal to run after the initial pressurization. Bad new parts have not been ruled out, but we aren’t sure which one. We are stumped. We have the Chilton’s manual and the 1984 Fiero service manual, and would greatly appreciate any help we can get.

[skibum1111]

Sounds like a bad fuel pressure regulator returning fuel to the tank, or the ecm is not getting a signal from the distributor to keep the fuel pump running. Start with the fuel pressure regulator, its fairly inexpensive and easy to replace. Had the one fail on an 86 sunturd that I had, took about 10 minutes to change it.