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Discussion Starter · #1 ·
The pump on my 88 RC isn't running.I lowered the tank to check voltage at connector and one wire is only showing .5 volts and another has a fluctuating reading only going up to about 7 volts. I don't have wiring diagram for the truck and I've traced the wires back to the computer.Everything seems intact but I thought there should be 12 volts at the pump.Can anyone give me some advice or help locate a schematic? Thanks.
 

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what are your computer failure codes? one possibility is the asd (auto shutdown relay). it is located on the driver side inner fender. it is the small squarish plastic housing relay. it has (4) wires going to/leaving it. the ones you are concerned with are the red wire 12 vdc from charging system. dark blue w/black tracer going to among other things the fuel pump. the computer picks ths asd about 2 to 3 seconds when you first turn the key on. (don't have to go to start position) you should hear the fuelpump run for 2-3 sec. this is controlled by the computer thru pick/drop of ads. the dark bl w/yellow tracer is the wire from the computer that picks the asd relay. if you get 12vdc on the dark blue w/black tracer during the 2-3 sec time frame, you prob have a bad fuel pump. good idea to also check for 12 vdc at the dark green w/black tracer during the 2-3 second timeframe after ign on. if you have 12 vdc on red asd rly wire and no 12 vdc on db/bk wire, either the relay is not being picked or the relay points are not contacting. good luck --sheriff--
 

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Discussion Starter · #3 ·
Thanks for the info. I checked the relay earlier and it worked fine and I checked voltage like you said,also fine. I figure its the pump but I also thought there should be 12v at pump.
 

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W100-77 said:
Thanks for the info. I checked the relay earlier and it worked fine and I checked voltage like you said,also fine. I figure its the pump but I also thought there should be 12v at pump.
dark green wire w/black tracer at the fuelpump should have 12 vdc during the 2-3 sec time frame w/key on. --sheriff--
 

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w100-77 --did you get your fuelpump problem straightened out? --sheriff--
 

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Discussion Starter · #6 ·
Sorry it took so long to get back but I left for vacation and just got a chance to get online. I removed the old pump and it was no good.Replaced it with Autozone pump on Sunday,truck quit running again on Tuesday.Same routine as last time and it just seems that I got a bad pump.Returned the pump today and will have to get another tomorrow.Has anyone had any luck with Pepboys products?They're the only place open tomorrow and I don't really want to wait untill Mon. to go to Napa.I've been driving my 77 and it only gets about 8 mpg. 50 mile roundtrip for day job plus my part-time lawn service is really starting to add up.
 
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