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Fuel system HELP!

2

2000 Grand Prix GT Blue

New member
I have a 99 gtp that recently died on me and i needed a new fuel pump, relays, and resistor. After replacing all that the car has run great for about a month until last night i went to start it and the fuel pump wasn't priming up at all. I had to leave it for the night because it was storming but this morning i went to fire it up and i heard the pump prime on the first try and it ran fine. To check i was ok i shut the car off and tried to start it again and sure enough i couldnt hear the pump prime and it wouldnt start.. relays felt hot so i pulled them out didnt hear any rattling in them i switched them and put them back in no change. Went back to the pump and had 12v at key on then faded to 3v after like 3 sec also had a constant 5v or maybe 3v on a diff wire dont remember. Went to start it agian and it started but died in like 2 sec. Then i went to the resistor and bypassed it with a paperclip and shes running fine and i was able to make it to work. I feel like i have a bigger problem than just a resistor.. Anyone had anything like this? Suggestions??
 


Let's go over how the system is supposed to work.

At key on, the pump gets a high speed signal for only a moment to prime the system. This explains the quick 12V and then it no longer being 12V.

Once the engine starts, the fuel pump is in low speed mode which uses the resistor. Which is known to go bad and cause a start/die situation. Your bypass puts the pump into high speed mode.

The question is.. what is not happening? I find it tough to believe that the pump, resistor and relays were all bad. That would lead me to think something bigger is going on electrically on the car.
 
Thats what I'm thinking. I just dont know where to start because like I said the resistor,pump and relays were all changed like a month ago. My car died on me and i had it towed to a shop because i didnt want to mess with it. They did the resistor because it was burnt looking at the connector. I had a cheap pump in it before that was probaly pulling to much current is what we thought. The relays made some noise shaking them so i just went and replaced those too. After all that it still didnt start so i put a new pump in and it was good. Now a month later this is going on.
 
Oh wait..you have a blue car. I found the issue. Blue cars are often troublesome.

Honestly though..I'm thinking it over.
 


Can I check the resistor with an ohm meter?? Right now Im seeing about .4 ohms at the resistor which is basically a short. So I dont understand how a wire will make the car run but the resistor will not. My mechanic seems to think my zzp pcm is damaged because he claims the resistor cant be bad again.
 
Any good mechanic knows that a new part can fail fast, because he's seen it happen. If bypassing the resistor is consistent in making he car run, then either the resistor or wiring to it has failed.
 
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