Impala Cranks and will not start after warmed up

knightrider999

I have a 2000 impala, and it generally starts when it's cold. Then when it's warm and you turn it off, it doesn't start (more so than not). I've replaced in the last few days, Crank sensor, Ignition control module, Fuel Pump, Intake Air Controller, Battery & Ignition Switch. I've seen some other posts that seem to come close to the issue, however, no one mentions not hearing the fuel pump when this condition occurs.

When I turn off the car, and the check engine light does not come on when I turn the key back to on, this is when my fuel pump decides it doesn't want to work, Eventually (mainly when cold again), I can turn the key forward, and when the check engine light comes on (prior to starting), my fuel pump works and all is fine till the next time it's warm and I turn it off.

The only thing I can think of is my BCM is going bad, I've replaced nearly everything else that's in the books to make this work, (Some in which needed changing anyway, ICM, IAC, Crank sensor. And now I'm stuck, I hope it could be something other than my BCM so if anyone has any other idea's, I'm all ears...

knightrider999

After Troubleshooting this issue, I found that the ECM had been unplugged at somepoint and the rubber seal was stuck to the ECM and not the harness as it was to be placed in. Once I placed it in the harness, and plugged it back in, all the rest of the troubles disappeared. Now my wifes impala runs better than mine. I'm starting to feel like a near expert on these cars.

Mr_Shiftright

Glad you mentioned this, as I was going to say (sure you were Shiftright) that the ECM powers on the CEL, so to look at that harness.

Good snooping on that one. If this occurs again, you might examine that connection more closely for possible corrosion issues.

thecardoc3

A little product knowledge can give a completely different perspective here. If you look up the check engine light operational characteristics you will find that the pcm commands the instrument cluster to turn the light on based on commands from the PCM via the high speed data bus when a trouble code sets in the emissions system. The instrument cluster itself turns the light on for a bulb check at key on and will also turn it on if it loses communication with the PCM.

knightrider999 said:

I have a 2000 impala,
When I turn off the car, and the check engine light does not come on when I turn the key back to on, this is when my fuel pump decides it doesn't want to work, Eventually (mainly when cold again), I can turn the key forward, and when the check engine light comes on (prior to starting), my fuel pump works and all is fine till the next time it's warm and I turn it off.

Compare this to what I wrote above.

knightrider999 said:

The only thing I can think of is my BCM is going bad, I've replaced nearly everything else that's in the books to make this work, (Some in which needed changing anyway, ICM, IAC, Crank sensor. And now I'm stuck, I hope it could be something other than my BCM so if anyone has any other idea's, I'm all ears...

At this point since it appears to be working during the most recent re-start attempts, the only thing proven is that it is random, but does tend to occur with a hot(warm) restart. With an appropriate scan tool, during a failure the first step is to see if any modules are active on the data bus or not. By the description, no check engine light it would be expected that even if everything else does turn on, its the IPC (instrument cluster) that one will find absent from the system. If the IPC and the PCM (among others) are both missing from the bus, then you have the first finger that is pointing in the right direction.