I have a 1996 Bonneville, 3800. I have replaced the fuel pump and the ICM as well as the fuel pump relay on the passenger side of the car.

Here is what happens. It is extremely intermittent, sometimes it goes for days, and has been driven on trips over an hour long without doing it. When it happens there is no warning, no rough idle, it just dies, or will not start. When it dies it usually will not start right away. One time it was more than a day before it would start, but normally it is a few minutes to half an hour. When it will not start, I do not hear the fuel pump run as it usually does when I turn the ignition switch to on.

Relay - on the fuel pump relay I stuck some wires in by the prongs on the switch side of the relay. I have a voltage meter connected. When the pump is running the voltage drops to practically nothing since there would be little drop across a closed switch. When first turned on, the voltage drops as it pumps up pressure then when it stops it goes to 12V. (telling me the switch is open again) While running it is .02, during the initial On mode as well as while the car is running. When the car dies the voltage is 12V so I know there is still a circuit through the fuel pump but that the switch in the relay is not closed. When this happens and I turn the ignition off, when I turn it back to the On position with my hand on the relay I can feel it click, but the switch in the relay has not closed. (Reminder I have replaced the relay with the same result).

Grounds - I ran an extra new ground wire from the ICM to where the battery grounds connect on the fender/firewall. I have also checked the ground wires on the passenger side of the car where the relays are. They look very good and test fine from the terminal block to the bolt which mounts the wire coming from the block to the car body.

Spark - I DO have spark.

The last time it happened, I sprayed some gasoline into the air intake and the car did run until the fuel was used up, when I repeated the relay closed and the car continued to run.

Other things - I watched to be sure rpm's were showing on the tach. as I cranked when it would not run and they do register so I do not think it is related to that sensor. Fuel Pressure - when the car will not run, it will still shoot gas out the pressure test valve. I do not have a guage to test.. but I deduce from above the pressure is fine when the pump is running. Coils - when I replaced the ICM I tested the Ohms across the top terminals of the coils. They were all about the same 5.4K (the paper which came with the ICM said they should be between 6 and 11K, the autozone mechanic said to just be sure they were close to the same). Not sure it could be a coil problem since it does not run rough at all.

I checked computer codes on it last week after it has done this several times. After over 200K miles, the car has never had a single code in the computer. Whatever is causing it is not setting a code.

I do not have a schematic to trace back from the active side of the fuel relay to see if it is some kind of grounding problem in that circuit or how it relates to the ignition switch. (when it dies I have all the normal dash lights).

Thank you for the help and suggestions.

Dan.

Welcome to AF, if it has fuel pressure and spark and it will only run on fuel sprayed into the intake it sounds like the injectors are not pulsing, when this happens get a noid lite on the injectors and look for pulse. You could have one bad injector that pulls down the pulse to others and the engine will not run, this assumes proper fuel press.

Thank you maxwedge for the response and the welcome. I have narrowed the problem to whatever it is, stops sending the signal, or at least a strong enough one to the relay that turns the fuel pump on and keeps it on. When it dies it is because something has caused the relay to open. Is it possible that a bad injector could do that? And if one was bad wouldn't it run rough when it was running? I do not have a lite at the moment. Is there any way to test those with a DVM?

Thank you,

Dan.


Welcome to AF, if it has fuel pressure and spark and it will only run on fuel sprayed into the intake it sounds like the injectors are not pulsing, when this happens get a noid lite on the injectors and look for pulse. You could have one bad injector that pulls down the pulse to others and the engine will not run, this assumes proper fuel press.

Update - I have narrowed it to something downstream of the relay. I have verified the ground wire listed as A on the plug for the fuel pump under the car near the tank, it does have continuity from there to the grounding terminal located on the driver's side. That terminal was damp and corroded. Cleaning it may have fixed the problem. If not I will need to track the gray wire from that plug by the tank. It is in the same bundle by the driver's side. I must go somewhere else before it gets to the relay because I did not have continuity between it on the plug and either side of the relay. All I can tell so far is it goes up a chaseway then goes into a huge bundle of wires all taped up. I have no idea where it goes from there. Can anyone tell me where the gray wire (which is the hot wire to the fuel pump) goes from there?

Thank you,

Daniel

There are decent wiring diagrams at autozone.com, repair guides.

can almost guarantee its the crank position sensor

can almost guarantee its the crank position sensor

The OP claims he has spark during this event, that eliminates the CPS, no?

nevermind i didnt relize he had spark. did you check the security system? these go bad easily you can test the diode in your ignition key and buy a resistor with that same resistance and bypass the vats system, which only shuts off the fuel supply when not working properly.

The VATS will not shut off the car once its already running...

If the cat looses fuel pule at the injector its still possible ti have a bad crank sensor.. When the car stalls is there a pulse at the injector?

Does this happen at any time... Hot or cold.. Does anything seem to be associated with this?

The VATS will not shut off the car once its already running...

If the cat looses fuel pule at the injector its still possible ti have a bad crank sensor.. When the car stalls is there a pulse at the injector?

Does this happen at any time... Hot or cold.. Does anything seem to be associated with this?

Again, the OP claims spark is present when this happens, not the cps.

Sorry it took so long to get back with my solution. I didn't realize I had forgotten until I was cleaning out emails.

My problem was related to a ground terminal which is located on the drivers side floorboard just under the front of the door. (there is one like it on the opposite side but the fuel pump is grounded on the driver's side) The drain plug was clogged and it had gotten wet and corroded. I took the strip out and cleaned it off good. Put it back together and taped it up good. I also made sure the drain under the carpet on the floorboard was open again. No trouble since.

Re-cap - problem was caused by a bad fuel pump ground.

Thanks to all.

Daniel