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A common sign of a failing ECU is injector(s) hanging open, causing gas to dump out the exhaust... it just happened to me last week as a matter of fact.

EDIT: If its throwing a code, take it to a Autozone or Advanced Auto and have the code(s) read to shed any light on the problem. If there are no codes, what are some symptoms to your problem?
 

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A common sign of a failing ECU is injector(s) hanging open, causing gas to dump out the exhaust... it just happened to me last week as a matter of fact.

EDIT: If its throwing a code, take it to a Autozone or Advanced Auto and have the code(s) read to shed any light on the problem. If there are no codes, what are some symptoms to your problem?
That only applies to 94/95 4.6L MN12s. Also, Autozone and parts stores will only read OBDII cars.

Sometimes a computer will throw a code for itself. Generally though you'd have to test that all the output voltages are within spec and that it grounds the wires it is supposed to.
 

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That only applies to 94/95 4.6L MN12s. Also, Autozone and parts stores will only read OBDII cars.

Sometimes a computer will throw a code for itself. Generally though you'd have to test that all the output voltages are within spec and that it grounds the wires it is supposed to.
^ ah sorry, thanks for the correction master486. I didn't even pay attn to his car year and engine.
 

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Discussion Starter #6
So I should run over to autozone, advanced auto, napa, ect get their code reader to check my computer? Is it possible my computer was fried when my fuel pump wire shorted? I ran a new wire around the old one to eliminate the short, replaced the fuel pump relay and the EEC relay. I have voltage to the fuel pump relay, but it isn't clicking to turn the fuel pump on. I did accidently have the ignition on when I jumped the fuse so its the only thing I can think of is that I shorted the computer
 

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What is the car doing that makes you think you have a bad computer?
 

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Discussion Starter #8
not running

It started with a dead short with the wire running from the high current fuse box back to the fuel pump relay. Well after checking and checking I couldn't find the dead short, during my checking I jumped the fuse a couple times while checking, well unfortantly while doing this my friend left the key on. Luckly the fuel pump works, I replaced the whole wire, I replaced the fuel pump relay and the EEC relay, all other fuses are intact. At this point the only thing I can think of is when it was jumped I fried the computer
 

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OK, so the fuel pump is working, but no start. Does it crank? Spark? Injector pulse? You need to find out what is not working to prevent it from starting, and then we can examine that system to see where in the system the fault is. While it is possible to fry the computer, 99% of the time when a vehicle won't start, it isn't the computer. First check to see if you have fuel pressure. If you do, see if the injectors are pulsing. If they are, see if you have spark. Get back to me with that info and we'll go from there diagnosing it.
 

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Discussion Starter #10
Well the fuel pump isn't turning on when I turn the key on thats the problem, I have new relays, power getting to the fuel pump relay, if I bypass the relay the pump runs. For some reason the relay isn't switching to send power to the pump. The engine does turn over, I haven't checked to see if I'm getting spark yet cause if there isn't any fuel being pumped then the spark would be useless anyways
 

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OK, stupid question...did you check to see if the inertia switch is tripped? Also when you jump the relay and the fuel pump runs, will the car run, or is it still a crank - no start even with the relay jumped?
 

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Discussion Starter #12
OK, stupid question...did you check to see if the inertia switch is tripped? Also when you jump the relay and the fuel pump runs, will the car run, or is it still a crank - no start even with the relay jumped?
yea I checked the switch and checked it to make sure it was in working order. I didn't do that yet cause I was under the impression that if I ran the pump at 12v would burn it out if I run it to long
 

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The pump is always running at 12V whenever the car is running, so that won't hurt it. The only reason for the computer to be involved at all is so it can run the pump for 2 seconds then shut it off when you first turn the key on. If the pump keeps running, the fuel pressure regulator would just release the pressure above 44psi back to the tank, and it would keep circulating the fuel. Some newer cars have a returnless fuel system, where pressure is regulated by pulsing the voltage to the fuel pump, and those you might burn out by running constantly, but not our cars.
 

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Discussion Starter #14
I thought the fuel pump has to run at 9v? Cause if I can I'll just bypass the relay and run the fuel pump manually from a 12v toggle switch
 

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Nope, the fuel pump runs on 12V all the time.
 

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Ok, do you have spark and injector pulse?
 
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