No-Go Third-Gen FormulaI hope you can help me concerning a problem with my '89 Firebird Formula 350. Recently when I was driving, the car completely shut itself off and would not restart. I had been driving it all day on both the highway and service roads. I hooked a fuel-pressure gauge to the fuel rail and didn't have any pressure, and I also listened and didn't hear the pump working. Once I got the car towed home and off the flatbed, it started and ran well.
This is the second time it's done this, the first being almost a year ago. My car has 58,000 miles and is driven regularly. I have replaced the following:* Bosch Platinum 4 plugs* Coil (ACDelco)* Spark plug wires from both Jeg's and AutoZone* Distributor cap and rotor* New 23-pound injectors from Jeg's
The car runs great and recently ran down the track in 14.8 seconds, so I don't think it's the fuel pump because it did the same thing last time. Could this be something electrical? I have checked fuses, the relay, and the alternator, and the battery is less than two years old.
The car has a few modifications-ported plenum/runners, airfoil, a cold-air kit, a full 3-inch exhaust, a 170-degree thermostat, pulleys, and a new chip-but nothing more than bolt-ons. Any help you can give me is appreciated.David HarrisVia Internet
Ray T. Bohacz responds:Intermittent problems are always the hardest ones to diagnose. If the engine stopped running and then stayed dead, the issue would be easy to find. But I can provide some helpful tips. The good thing is that you know the reason the engine quits is fuel-pump related. This will make the task a little simpler.
Start out by first doing a complete examination of the fuel-pump wiring-harness connector that is under the car. Unplug it and look at the terminals. Are they clean? Are any of the wires pulling out? Next, examine the ground circuit wire for the fuel pump. Do a visual inspection and then check it with an ohmmeter. The circuit should have less than 0.2 of ohm resistance. If the reading is higher, clean the ground circuit and recheck.
If these procedures prove inconclusive, then drop the ECM and do a wiggle-and-tap test. With the engine running, wiggle all of the wires and rap on the ECM with your fist. The engine should be oblivious to these actions. If the engine stumbles or stalls, there is either a loose solder joint in the ECM, or the wiring harness has a bad connection.
Also check the fuel-pump relay connections. This component should not induce a stall since the oil pressure switch is closed when the engine is running, and it completes the circuit to the fuel pump. But electricity is funny and often doesn't respond in the manner you would assume. That is why it is called "electrical theory."
If you still find nothing, replace the fuel pump with a new ACDelco unit. It is possible that the fuel pump has a weak internal connection that loses contact when heated. An indication of this is if an engine stalls when the fuel tank is low on gasoline. As a matter of fact when I had my shop, the wife of a previous HPP editor had a car that would respond exactly as your Firebird-an intermittent stall, a tow, and then it would start and run for one month before it acted up again. It ended up being the fuel pump.