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Discussion Starter · #1 ·
Its a 1988 chevy 1500 with a 350 engine. I just bought this truck ,and it was running but had to get the fuel tank cleaned and replaced fuel pump and sending unit cause it was all gunked up from old gas. just put it all together and now it want run. meaning fuel pump. and plus there is no fire at fuse under hood on firewall. I checked fire at plugin were it connects to sending unit,and with the plug unpluged, it has fire on middle wire but when i plug it up it loses fire, meaning i took a test light and tested both middle wires on each side of the plug ends ,but i can unhook it and the middle has fire.can someone tell me how the fuse might have lost its fire and and were should i start. Im not that good with this kind of problem but with some good advice i know i can fix it. thanks
 

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robbie43 said:
Its a 1988 chevy 1500 with a 350 engine. I just bought this truck ,and it was running but had to get the fuel tank cleaned and replaced fuel pump and sending unit cause it was all gunked up from old gas. just put it all together and now it want run. meaning fuel pump. and plus there is no fire at fuse under hood on firewall. I checked fire at plugin were it connects to sending unit,and with the plug unpluged, it has fire on middle wire but when i plug it up it loses fire, meaning i took a test light and tested both middle wires on each side of the plug ends ,but i can unhook it and the middle has fire.can someone tell me how the fuse might have lost its fire and and were should i start. Im not that good with this kind of problem but with some good advice i know i can fix it. thanks
Hmmmmmm. I'm kinda confused. What middle wires are you talking about? Can you post some pictures?
 

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Discussion Starter · #3 ·
S10 Racer said:
Hmmmmmm. I'm kinda confused. What middle wires are you talking about? Can you post some pictures?
Im talking about were it plugs together at the fuel tank. or from truck wire harnest to fuel pump at fuel tank. the plug has 3 wires , 3 going from plug to fuse box , other side of plug goes to fuel pump in tank.
 

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The wiring schematic on www.autozone.com indicates that the ECM energizes the fuel pump relay. This will run the pump for a few seconds to pressurize the system.
Once the engine starts and builds oil pressure a separate oil pressure switch closes and powers the fuel pump.
There is also a fuel pump prime connection (test) point under the hood. This test point is for priming and testing only
To test the fuel pump, run a jumper from the battery + to this test point.
Also, connect a fuel pressure gauge to the fuel pressure test port.
The TAN/WHITE wire is the fuel pump wire. You must have 12 volt+ on this wire for the fuel pump to run. Also, the fuel tank must be solidly grounded for the fuel pump the work.

vicrod
 

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Discussion Starter · #5 ·
vicrod said:
The wiring schematic on www.autozone.com indicates that the ECM energizes the fuel pump relay. This will run the pump for a few seconds to pressurize the system.
Once the engine starts and builds oil pressure a separate oil pressure switch closes and powers the fuel pump.
There is also a fuel pump prime connection (test) point under the hood. This test point is for priming and testing only
To test the fuel pump, run a jumper from the battery + to this test point.
Also, connect a fuel pressure gauge to the fuel pressure test port.
The TAN/WHITE wire is the fuel pump wire. You must have 12 volt+ on this wire for the fuel pump to run. Also, the fuel tank must be solidly grounded for the fuel pump the work.

vicrod
thankyou for your advice , after reading your post ,i went and checked the ground at the tank,and put a test light clamp on the ground bolt and touched a pos wire ,and light didnt lite up, so i took bolt off and cleaned it and frame good and hooked it back up and turned the key on and i heard the pump for about 2-3 sec then cranked it up :thumbup:
 
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