2G ignition problem? fuel pump randomly primes when car is off.

[foxracing4500]

I never had this kind of problem so I am sorta lost, my car has basic boltons, fuel pump is stock, recently got my 95 eprom ecu done at ecmlink, caps included. The problem is I go down to my garage where its stored and always have the hood open. I always check out my fuel pressure regulator gauge and sometimes it will read 43 psi after the car has been sitting and sometimes it will read zero like it should. I went down to the garage today to fire her up and the battery is dead. My only guess is its ignition related, in ECMlink I have the fuel pump prime OFF. I am lost I dont know what it could be and no I DONT leave the key in the ignition but why is it randomly priming the fuel pump? It should only prime when I turn over the engine.

 

[Dsmkauai]

Is the pump rewired? And what makes you think the pump is turning on? If you leave the car sitting for awhile it's always best to remove negative terminal on battery. Also how old is the battery and what's the temp where you are?

 

[foxracing4500]

Fuel pump isnt rewired. To answer that, how does my car loss fuel pressure and randomly gain it back without me starting the car. Im just going off what the fpr gauge says when i walk by it, i know they normally bleed off to zero after sitting. Battery is great just got it over the summer and im from PA. Its been around mid 30's here. Its the wildest thing and i swear im not trolling. But i hate not knowing what causes that, when every other dsm primes when cranking.

 

[pauleyman]

What makes you think it should bleed to zero?
So you've seen it at zero and then later it isn't?
Or you've noticed some days it's at zero after a bit and other days it holds pressure?

 

[foxracing4500]

Always had fuelab fpr's and they usually bleed off to zero after an hour. Yeah i seen it at zero and later it reads 43 psi. Its happened a few times i would like to get it recorded to show everyone. My guage does have a crack in the glass if that matters. I just wonder if it caused my battery to drain. Either way its not that big of a deal i can disconnect the battery if need be.

 

[talon91tsiawd1]

You ever figure this out? This is happening to my car also, I was sitting in it working on the interior and I heard the fuel pump come on about 4 times with in 4 hours.

 

[steve]

I heard the fuel pump come on about 4 times with in 4 hours.

For the fuel pump to run you have to provide power to it and ground. Normally (as in not rewired) the pump and ignition are powered from the ignition switch via the MPI relay and it's grounded to the chassis in the rear below the hatch lock. To turn on both the Ignition switch and the MPI relay have to be turned on. For the MPI relay to be on you have to ground the relay coil pin that goes to the ECU.

If your pump is rewired you need to tell us how it's done.

 

[talon91tsiawd1]

The car is stock wired.

For the fuel pump to run you have to provide power to it and ground. Normally (as in not rewired) the pump and ignition are powered from the ignition switch via the MPI relay and it's grounded to the chassis in the rear below the hatch lock. To turn on both the Ignition switch and the MPI relay have to be turned on. For the MPI relay to be on you have to ground the relay coil pin that goes to the ECU.

If your pump is rewired you need to tell us how it's done.

 

[steve]

Given that, I hope I've provided the background details to allow you to identify why it's doing what you say it's doing. It shouldn't unless you have the ignition on and something is triggering the MPI relay to activate the pump.

I forgot to mention that there is a second input for the fuel pump on a 1G since this is a 2G thread, the signal from the ignition switch to the starter. Either the ECU grounding it's pin or feeding 12v to the starter solenoid will trigger the relay.

 

[talon91tsiawd1]

Thank you for the info this is actually gapping in my 2g but I get the jist of it. I'll check the mpi relay. ,

Given that I hope I've provided the background details to allow you to identify why it's doing what you say it's doing. It shouldn't unless you have the ignition on and something is triggering the MPI relay to activate the pump.

I forgot to mention that there is a second input for the fuel pump on a 1G since this is a 2G thread, the signal from the ignition switch to the starter. Either the ECU grounding it's pin or feeding 12v to the starter solenoid will trigger the relay.

 

[JeffGS-T97]

Pull up the carpet follow the wires from the pump. If you have worked on the interior one of the wires could be placed in a pinch point causing the power wire to ground in the car if it has become bare or crushed. Had that problem last summer when i installed my saftey harness bar.