Electrical short
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Electrical short
I have a 91 F150 4X4 and the battery goes dead in about 6 to 8 hrs of off time. I replaced the battery and the altenator, nothing helps. This started suddenly, the alternator is putting out 13.62 at idle and if I disconnect the battery it holds it's charge. I have looked for lights and items that may stay on and have found nothing, any ideas where to look next? is this a common thing?
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From: Bel Air USA
Electrical short
You may be able to start pulling fuses. If you pull a fuse and then insert it back and get a spark, that cicuit will be drawing current. Don't forget that the dome light ciruit should be drawing current with the door open. If you can come by an ammeter, you could insert it in one of the battery leads and start pulling fuses. When the current drops you have found your circuit. But remember that there are some devices in the truck that will draw a small amount of current even when turned off (e.g. radio memory, ECM).
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Electrical short
Here is a way that is all written out for you.
[link:www.inliners.org/tech/tech6.html|Finding an Electrical Short]
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Electrical short
Hi. I have found many older EEC and fuel pump relays that stick on. Your time of 6-8 hours for the battery to die sounds about right for a fuel pump relay sticking on. I have had one that would only stick on every once in a while. I found it a good idea to replace fuel pump relays about every 100,000 kms. Hope this helps you out.
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Electrical short
Thanks for the help I pulled all fuses one by one and the only one that made the light go off was the interior lamp/heat/radio fuse. I then hooked up my multi meter and saw that I had 12/13 volts and even with the fuse out it was steady dropping. I put the fuse back in and it did not increase the drop or decrease it. I put my mutli meter on (everything off) and I had a reading of 12.50 two hours later I checked and I had a reading of 12.20. The only thing different is I think I switched fuel tanks, when I closed the door this evening I heard a faint whine from the rear off the truck. is this normal or could it be a fuel pump going bad and getting stuck and drawing power?
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Electrical short
Considering Fuel systems (Computer) use GROUND to actuate the fuel pump I would be checking that circuit.
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Joined: Aug 1999
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From: Bel Air USA
Electrical short
If you hear your fuel pump running with the key off, your fuel pump relay is either stuck or energized when it shouldn't be. A bad fuel pump will not make your battery go dead with the key off. The fuel pump relay will. The front and rear tanks use the same fuel pump relay. The selector switch on the dash is the only difference between the two tanks.
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Electrical short
Relays are on the left (driver's) side of engine compartment. Most likly have 2 relays side by side in a black cover /bracket. One will be green and black and one will be brown and black. you want the green one. pull that one out. There may by a dia on the relay you can use when checking it. have a good day and let me know how you make out.
Post Fiend
Joined: Nov 2002
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From: Memphis, TN
Electrical short
For a "permanent" fix, convert ALL your vital relays to the Bosch-style used on '92-current F-series and many other brands. They're the most common & reliable relay on the market, and they're much easier to wire up, replace, & diagnose than that old Ford type.
