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  1. #11
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    Nov 2010
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    San Tan Valley az
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    Funny my 87 only had 2 relays that is could see. I am going to look for the ignition one first. I am thinking as bad as the fuses were, that the smell and little of smoke came from them, right after I replaced them and got them out of the cab the smell was gone. So Relay, then ECU. I am really surprised that the fuel selector valve took everything out, I think the relay could not move and loaded everything until the fuses did their job.

  2. #12
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    Well i finally found a melting point, the transistor circuit board, the transistor melted right through the case.

  3. #13
    Legend
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    The transistor board in what? The ecu?
    1988 Chevy C-3500 2wd (no pic)
    350 c.i. 5.7 L Stock Block, 4 Bolt Mains
    L-31 Vortec Heads, Edelbrock Cam & Intake,
    Holley 650, Flowtech Headers, Magnaflow exh.
    Jet Trans 700R4, B&M Ratchet, 4:10 gears,
    3" susp. lift kit "shadetree"
    No rev limiter, No speed limiter lol


  4. #14
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    San Tan Valley az
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    Well that was what I read on one schematic, the other was hot fuel module, GM has it as part# 10052973 Module AS 3900, others show it as a fuel pump control module.

    Government description
    A device specifically designed to (1) increase the pressure of, (2) meter the amount of, (3) control the distribution of liquid fuel received directly or indirectly from the TANK, FUEL, ENGINE to the individual air inlet tubes or combustion chambers of gasoline or diesel engines.

    None the less it was fried. Went to the dealership and was told they had not sold one in 15 years. The truck does run and shut off with the pcb removed. So i will pickup one on the internet. I have not reviewed why it allowed the current to flow the way it did but did read it's original function was to allow the fuel to run for an additional 11 seconds when the motor is hot, because the cooler fuel will make it easier to start.

  5. #15
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    OK Aficio, I see it on my wiring diagram for 1988 model year. It is also called a "hot fuel module" & it shows how it is connected. It is wired to the fuel tank select switch with a tan & white wire. This wire is also bridged to the oil pressure switch, & continues on to the fuel pump relay. The module is also connected to the fuse via the pink & black wire, & is grounded with the black & white wire. This is the first I have ever heard of this module. Where was yours located??
    1988 Chevy C-3500 2wd (no pic)
    350 c.i. 5.7 L Stock Block, 4 Bolt Mains
    L-31 Vortec Heads, Edelbrock Cam & Intake,
    Holley 650, Flowtech Headers, Magnaflow exh.
    Jet Trans 700R4, B&M Ratchet, 4:10 gears,
    3" susp. lift kit "shadetree"
    No rev limiter, No speed limiter lol


  6. #16
    Jr. Apprentice
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    Nov 2010
    Location
    San Tan Valley az
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    It was under the dash on the right hand side of the steering column. it is attached with one of those puch through the hole fasteners but will slide off. The case is black plastic about 3x4,From what i have seen when you buy them they come with the case and wires, but from my vantage point it would be easier to just open the case and use a pair of needle nose pliers and slide the old board out. This way you would not have to fish out the other side and disconnect and reconnect the unit.
    I tell you what if i had not found where it had burned through the case i would have never gone this direction.

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