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f/p injeters fuse keeps blowing out please help !!
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pedro702
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Jun 26, 2008, 7:51 PM
Post #1 of 3
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f/p injeters fuse keeps blowing out please help !!
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i guys i have 19992 oldmobile achieva v6 3.3 automatic i changed the fule pump is good but the fuse for fuel pump /fuel injecters blows out right away as ssoon as i put the ignition on please help im thinking maybe bad computer??????
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way2old
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/ Moderator
Jun 27, 2008, 6:07 AM
Post #2 of 3
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Re: f/p injeters fuse keeps blowing out please help !!
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Was it doing the same thing before you changed the fuel pump? If not, the pump assembly or wiring on new pump is bad. If it was doing the same thing, somewhere in the system you have an ignition power wire that is touching metal or a ground wire. Without testing tools, all you can do is unplug connectors to see where the fuse quits blowing. If you unplug it at the tank, and fuse stays good, the pump wiring is at fault, new or not. If it still blows, go to next connection and try again. Just have a supply of fuses. Good luck.
Being way2old is why I need help from younger minds
(This post was edited by way2old on Jun 27, 2008, 6:08 AM)
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flgmtech1
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Jul 4, 2008, 5:06 PM
Post #3 of 3
(1696 views)
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Re: f/p injeters fuse keeps blowing out please help !!
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 all electrical problems are solved with a plan of attack and this plan beings with a good schematic and a basic understanding of electricity. The schematic above is for your car. The fuse in question is the F/P Inect 20Amp fuse. or, the FUel Pump and inector fuse/ This means the fuse that is blowing not only goes through the Fuel Pump relay, but splits off at the relay pin 4 leg and goes off to provide battery voltage to all 6 injectors. GM provides a constant 12 volts with key on, to all the injectors via circuit 839 off of splice S161, then the PCM toggles on and off the Ground. SO the pulsing light you see when you are testing at the injectore themselves is actually always hot it is illuminating the noid light when the PCM is supplying the ground.
So either you have a short to ground on 839 between the fuse and anyone of the injectors or between the fuse and the relay. IF it were after the relay the relay would simply switch on and off rapidly and in some cases melt.
The first thing to do is not use any more fuses. Instead obtain a volt meter or you could even take a 1156 bulb attatch two wires one to the bulbs case ground and the other to the element on the bottom. This can be done with simple solder, then electrical tape around the bulb and you just made a short tester. Or you can use a test light from battery positive not negative to test short to ground, and the other way around for a short to voltage.
The idea is to remove the fuel pump fuse and the fuel pump relay which is located under the hood at the center of the dash
remove both the realy and the fuse, now using your test light to ground test both sides of the fuse DO THIS FIRST, the reason being is one side of the leg will have battery voltage this is the main feed side and the other should now be open but it will most likely be grounded. So once you know whihc side of the fuse is HOT switch the test light from the battery ground to the battery positive and place the test light into the other side of the fuse terminal, the side that DID NOT light up when tested with battery ground, this one will more than likely also light up, that is because it is shorted to ground. Now, you have illiminated the relay and the Fuel pump and everything up stream from the relay.
Time to locate the splice S161,
or you can leave the test light in place, and one by one disconnect each fuel injector and stop when the light goes out, if it does not go out, disconnect the oil pressure switch. if the light still stays on with all the fuel injectors disconnected and the oil pressure switch disconnected, you now have to go to the splice and find out which leg of the circuit is grounded.
It is time consuming but well worth the effort as it will solve your issue and save you allot of money for diagnosis as electrical diagnosis is by the hour in most cases.
If there is anything else I can help you with please let me know.
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