Car won't start MPI fuse keeps blowin

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GR93tsi

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Discussion starter · #1 · Jul 15, 2003

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I was driving my car when it just died at reg. speed limit, pulled over and it wouldn't start. The inline fuse on my fuel pump rewire was blown and my MPI fuse was blown. I changed those out and put in a new 30 volt relay in just in case. tried to start it and the MPI fuse blew again, but not the inline. I kept changing it, and checking grounds, but just keeps blowing the MPI fuse. My car won't start!?!?! Ahhh whys it blowing?

 

James92TSi

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#2 · Jul 15, 2003

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Sounds like you have a short somewhere on the stock fuel pump wire.

 

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GR93tsi

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Discussion starter · #3 · Jul 16, 2003

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maybe when I changed out the relay I put the connections back on the wrong way, anyone have a diagram of the wiring to the relay? thanks.

 

James92TSi

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#4 · Jul 16, 2003

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85 stock fuel pump +12v wire
86 ground

30 fused +12v constant from battery
87 to fuel pump

87a (not used)


I have those grouped in pairs because they could be swapped either way and still function the same (i.e. you could have 85 ground, 86 stock FP +12v wire, and it would work exactly the same.... same thing with the 30/87 pair).

 

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GR93tsi

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Discussion starter · #5 · Jul 16, 2003

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Man, then I have no clue why this MPI fuse keeps blowing when I try to turn the car over, because I had the relay right and no bad visible grounds. I made no changes to the car since last fall and it has been fine ever since. I was just driving down the street and "POP" there goes the fuse and it won't stop blowing.

 

James92TSi

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#6 · Jul 16, 2003

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The MPI relay could be screwed up, but I really don't see how. Maybe try swapping out if you have a spare one?

 

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GR93tsi

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Discussion starter · #7 · Jul 16, 2003

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Do you know where the mpi relay is located, and is there a way to tell if a relay is good or bad, besides testing it, i always wanted to know this question.

 

James92TSi

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#8 · Jul 16, 2003

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It's bolted inside the passenger side of the center console.

I never really figured out how to test the MPI relay, I just replace it with a known working spare to see if it's dead.

But to test a relay, you apply voltage across the coil terminals, and test for a change in continuity on the load terminals.

 

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GR93tsi

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Discussion starter · #9 · Jul 16, 2003

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If I have no mpi fuse in place and turn my car to accesory, will the mpi relay click, will it even click even if the fuse was in, and not blown? if you understand that.

 

James92TSi

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#10 · Jul 16, 2003

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It won't click until you turn the key to ON, and only if there is a MPI fuse installed.

 

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FastRed

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#11 · Jul 16, 2003

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The oxygen sensor heater is powered from the MPI circuit. The isolation on the wiring harness is often cracked right at the O2 sensor connector shorting the wires and blowing the MPI fuse. I have seen several 1Gs suffer from this.

FastRed

 

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GR93tsi

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Discussion starter · #12 · Jul 16, 2003

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I will check that out, I actually just walked out to the garage and found my boost control solnoid laying there and the positive wire was corroded and fell out of the harness, was just lying on the frame, (oops) could this may have something to do with it? I have no other fuse to test with since I blew the others and its 3 in the morning

 

James92TSi

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#13 · Jul 16, 2003

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ABSOLUTELY!!!!! That red BCS wire is +12v from the ECU power supply circuit... aka the MPI circuit.

You may have just found your problem.

 

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FastRed

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#14 · Jul 16, 2003

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Something is pissing off the fuse. Most likely it's not the relay, they fail open. You need to chase the short. If you don't have any more fuses.... a single small wire pulled from the harness takes about 5-6A for a short time. Use it at your own risk.

FastRed

 

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GR93tsi

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Discussion starter · #15 · Jul 16, 2003

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I wish you could see the smile on my face from that response thats the best damn thing i've heard all day, in the morning I will throw in a new fuse and see what happens. I was having problems before with a grounding issue (which I thought) and it would kill out on me with 0% power. put a new - terminal on and cable, added a big grounding strap, and the problem went away for months til now in a different manner. I'm sure this is all falling back on my carelessness to cover up that damn harness when I put on my boost controller. I'll post what happens. Thanks

 

James92TSi

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#16 · Jul 16, 2003

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Yup.. insulate that wire (you might want to take care of the whole harness while you're at it, since you're not using the BCS anymore), and give it a go.

Hope it works for you.

 

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GR93tsi

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Discussion starter · #17 · Jul 16, 2003

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Thanks for the help, I have been with DSM's for a bit but for some reason, I never saw this site before. just signed up today. Looking forward to the forum.

 

James92TSi

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#18 · Jul 16, 2003

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Cool, welcome to the board.

Let me know if that BCS wire was indeed the problem.

 

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GR93tsi

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Discussion starter · #19 · Jul 16, 2003

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Took care of that harness today, threw in a new fuse, and I'm back boostin. It was only one day without my talon and I missed it already. Thanks for the help!