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Author Topic: need electricity at fuel pump, 87 Suburban  (Read 1796 times)

Offline Nairod

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need electricity at fuel pump, 87 Suburban
« on: November 22, 2018, 04:53:17 PM »
Newbie here...

I have an 87 Suburban, 2wd, auto, 454.  Won't start but will run on starting fluid.  Had a new fuel pump put in 3 years ago but sat idle til now.  I had to drop the tank to put it in.

This time I cut an access panel in the floor pan.  Using a 12v test light, w/ignition on, neither wire shows electricity present.  I cleaned a bright and shiny spot on the gas tank to use as a ground.

I would like help finding the fuel pump fuse, any relays, any oil pressure sensors, etc.  I am not familiar at all with this vehicle and there is nothing obvious to me - not even a fuse block in the engine bay.

It appears to have two relays next to each other on the pass side of the firewall.  Can't hear them clicking when cycling the ignition but ? I don't know what they're even for.

Thanks if you can help!

Thanks!
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Offline hatzie

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Re: need electricity at fuel pump, 87 Suburban
« Reply #1 on: November 22, 2018, 06:30:30 PM »
One of the firewall relays is the fuel pump relay and the other is the kickdown relay for the TH400.  The fuel pump relay will have a fat red wire with a female Packerd 56 disconnect dangling from it.  That red wire is the fuel pump power test lead.

I posted a dual tank theory of operation that has a bunch of the RV series fuel pump power information.  I can't remember if I posted it on this board as well as the other two squarebody forums I frequent. 
If you download the 1987 driveability manual it has detailed info on the fuel pump circuit.
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Offline Nairod

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Re: need electricity at fuel pump, 87 Suburban
« Reply #2 on: November 22, 2018, 06:49:05 PM »
Thanks, that's a big help. 

I tried jumping it but no luck at the pump.  I will try again tomorrow and see if I can get my test light to light up at the pump when I jumper it again.
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Offline Irish_Alley

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Re: need electricity at fuel pump, 87 Suburban
« Reply #3 on: November 23, 2018, 10:39:17 PM »
heres a few diagrams and trouble shooting guides
http://forum.73-87chevytrucks.com/smforum/index.php?action=dlattach;topic=23791.0;attach=19850;image

some are for a dual tank, just ignore them
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Offline Rapid Roy

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Re: need electricity at fuel pump, 87 Suburban
« Reply #4 on: November 24, 2018, 08:21:36 AM »
Welcome
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Offline LW

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Re: need electricity at fuel pump, 87 Suburban
« Reply #5 on: November 26, 2018, 09:32:00 AM »
Did you ever figure out your issue?  I am having the same problem with my 88 Blazer.  The pink wire at the tank is the signal wire to the fuel guage.  You should be looking for power to the brown wire with white tracer
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