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87 TBI blowing IGN fuse all of a sudden?!

999 views 2 replies 2 participants last post by  vicrod 
#1 ·
87 454 TBI has other issues like running rich but that's probably unrelated.

Always started fine but from one day to the next has decided to start blowing the IGN fuse as soon as I turn the ignition on.

Poured some fuel down the TBI and it ran a few seconds, so spark not the issue, fuel delivery.

Crawled under the Suburban and found a wiring coming off the pump. One black, white and one purple. Hooked up a wire to the +12v on the battery straight to the pump and presto starts right up and runs. (also my fuel gauge seems to be grounded out as it shows way over full all the time) maybe the 12v to the fuel pump is grounding out too?

What else is on that IGN 12v?

It's worth noting that once that truck has a run a few minutes and is switched off the fuel pump makes a ticking noise that sounds like a bouncing marble coming directly out of the fuel tank.

Anyways, what could be grounding out? Or is it the obvious? Anyone have a daigram on these motors of which wire is which? If I could get my fuel gauge fixed to that would be a bonus!

thanks in advance,
 
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#3 ·
When you power the fuel pump direct it runs OK but I would check the current draw. The pump could still have internal problems and be causing the fuse to blow. Anything over 10 amps suspect the pump to be going bad.
Also the fuel gauge sender (in the tank) is powered by the same fuse as the pump. It could be causing the fuse to blow.
Beyond that there is the fuel prime relay, the hot fuel module and the oil pressure switch (fuel pump run) are not likely to be causing the fuse to blow.
You can get the wiring diagrams at www.autozone.com . You need to register then select -- do-it-yourself, then -- repair info, then -- enter vehicle, then -- select vehicle repair guide, then -- select chassis electrical, then -- select wiring diagrams.

vicrod
 
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