1987 tbi chevy truck fuel problem

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#1
I took my truck apart last june. Everything then was working fine just wanted to restore it a bit. As of now the bed and front clip are removed but everything else is put back together. I went to start it the other night and noticed as soon as i turned the key no fuel pump hmmm. Unable to find my test light i just hooked up a 12v into the fuel pump plug and still nothing so i beat on the tank and all was good. So they must have frozen from sitting(dual tanks). so i plugged them back in and went to start it. Again nothing. So i just figured my fuel pumps werent getting juice so i just did the same thing with the battery and left the pump running while i turned the key. Nothing out of the injectors so apparently my whole fuel system isnt getting power. No blown fuses and all grounds hooked up and the guages all read zero so they are getting power. Is there anything special in the lighting harness or in the clip that has to do with fuel?
 
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#2
Did you happen to have the connector for the fuel pump relay unplugged?....Jm..

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#3
Yeah anything obvious i have already checked. I have had this apart about four times so i know a little bit. . . the only difference is is that i have never had the front clip off. I worked on it tonight and i didnt have power to the ecmb fuse in the box which i never bothered to check before. I jumped a hot wire from the aux power to the ecmb and now cab lights,dome, and injectors have juice. Now the only thing is the pumps. Thank you for the answer though!
 

kev2

wrench
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#4
you say the bed is off- then access to FP harness is easy...double check trhe system ground, also there is a FP TEST CONNECTOR on firewall breaks out around (red wire) FP relay use a fused jumper to supply 12v then ck gray wire at pump


is the FP relay clicking when key moved to run- only hot @5sec will need a helper - a test light into FP test connector would show if circuit is hot checking relay
 
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#5
Ok i will check the ground back there. . . my dad told me to do that awhile ago but i didnt because i had never taken anything off back there. But maybe throuhgout the sandblasting and the painting one got ripped off. . . . the only thing is that both tanks are doing the same thing which would mean that both fuel tank grounds are off assuming one is. Also no matter which way that i flipped my tank switch, i had about 5v of power to the plug on the top of the fuel tank on the drivers side. Sounds like a ground to me but i dont think that its the ones on the fuel pump but idk i will check it though thank you.

p. s- i noticed that have no power to the fuel tank switch inside my truck from right tank to left switch. Im pretty sure that there is supposed to be atleast one hot wire because thats how the switch works. . . idk babe in the woods with this tbi. . . stuff.
 
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#6
Dude, if you figure it out before I do please let me know what you did. I have an 1987 chevy 4x4 305 tbi That I have been fighting for about a month now. All of a sudden no fuel. I have posted here and got some goodd advise. I am to the point now that it has 6v at the tank connector using both connector wires and 10 volts if I ground the tester lead to the frame. My test light at the relay test lead does not come on unitl the engine stops cranking and then the relay clicks and the ligt comes on for about 2 seconds. I have replaced a bunch of parts( tank, sending unit, pump).
 
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#7
Only purpose of grounds is to save wire with a very bad side effect of causing electrolysis that causes corrosion as most metals are dissimilar. Prefer working on aircraft as a real wire is used for ground, electrolysis is a major destructive factor, but even predominate as composite materials that don't conduct are being used.

I have been known to add a ground wire to a vehicle, especially in the back far from the battery, the originating source. Do that especially when installing aftermarket amplifiers that ground loop currents can induce a lot of noise. Also feel it's dumb that all of our computers share a common electrical and signal ground, guess these young kids were sleeping in class during the common mode rejection principles session or maybe they don't cover that anymore. But with automotive, have to keep the stockholders happy. Certainly heard enough about that during my lifetime.

Sorry to post about common sense basics. But certainly is a major source of problems that could have been avoided.