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 Post subject: Fuel Pump Issue
 Post Posted: Fri Jan 26, 2007 2:19 pm 
 
I have an 88 Mustang, and I'm havin fuel pump problems. Before my fuel pump wouldn't shut off, it was running constantly, even after I shut the key off so we figured it was probably the fuel pump relay. I replaced the relay and now hte pump won't come on at all. I checked the inertia switch and it's fine, tried puttin the old relay back in, still no go. My plan today is to run a power wire from the battery and test to see if the pump is fried. If the pump ISN'T fried and it's just a ghetto wiring job the old guys did, then another mustang guy told me to do this... Run a new power wire from the battery, put a fuse in, and take that back to the fuel pump. Put an offroad light relay in there, and follow the instructions to wire that up, and viola. Sound good?


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 Post Posted: Fri Jan 26, 2007 2:32 pm 
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Use a volt meter or test light to see if there is power to the circuit that activates the relay. If that is good, then check the pump side of that relay to see if power is going thru. If it is, and the pump won't run then it's got to be a bad pump. If there is no power on the pump lead at the relay then you need to find out where that power source is and see why it's no voltage there. My guess is that since that thing would run with the key off then the circuit that feeds that pump is a direct line from a power source. In that case it could be as simple as a burnt out fuse of fuse link in that circuit feeding the relay.

I guess if push comes to shove you could run a new wire to the relay from the battery, fused of course, to power the relay and see if the ignition switch will turn it on and off.

This is what I hate about relays! And since all this wireing is in a harness it just makes it a pain in the ass to trouble shoot.

Anywho, run a few tests and let us know what you find.

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 Post Posted: Fri Jan 26, 2007 5:34 pm 
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It could be a pcm or ground circuit problem too. If I'm not mistaken, the fuel pump relay won't power up unless the EEC power relay is turning on. A lot of those relays look the same but function differently so when you plugged in the replacement you may have blown a fuse or fuse link. There should be a circuit at that relay that is hot all the time, if you don't have that then you either have an open circuit or fuse link. The fuse link is near the starter solenoid and you'll have to tug on it to see if it's burnt as the wire will melt inside the insulation and you won't be able to see it. The problem with wiring in a new fuel pump relay and circuit is that you may have an electrical problem that will still prevent the car from running.

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 Post Posted: Fri Jan 26, 2007 6:47 pm 
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Don't forget the "crash switch" the switch that kills the pump in case of a collision.. :-k

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6.07@110 on Alcohol Injection with a 4-link 4-6-12
Best 60' 1.2537 Alcohol Injection 4-29-11
Thru the Mufflers!!


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 Post Posted: Fri Jan 26, 2007 9:10 pm 
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us7race wrote:
Don't forget the "crash switch" the switch that kills the pump in case of a collision.. :-k


Jody,
That's what he meant by inertia switch :-k

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 Post Posted: Sat Jan 27, 2007 5:58 am 
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#-o :-#

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6.11@110 Gas
1.3718 Sixty Foot with the rear wheels Gas

6.07@110 on Alcohol Injection with a 4-link 4-6-12
Best 60' 1.2537 Alcohol Injection 4-29-11
Thru the Mufflers!!


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