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Thread: 93 Blazer 4.3 CPI Problem

  1. #1
    S.I.C. St Louis slash's Avatar
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    93 Blazer 4.3 CPI Problem

    Here's the deal. I bought a 93 Blazer with 86,000 miles on it. Ran fine for about 2 weeks now.

    Now, she'll start, idles fine. Turn the key forward and can hear fuel pump prime.

    If you either drive the truck 1/8 mile or just let it sit there and idle, it will die. Checked the fuel pump relay and it all checks out.

    Checked the Fuel pressure when the pump primes and I have 52-54 psi. Releave pressure on the guage, and start it. Once it starts, 52-54 psi. Pressure guage stays at 52 psi, but once it dies, relieve pressure on the guage, turn key off, turn key on to prime and cannot hear the fuel pump prime. Attempt to crank the engine, fuel pressure may or may not raise to 50 psi...

    Once it dies, it just dies completely, no sputter, just dead, truck will not start for 10 minutes. Then it will start, and do same thing. I do have spark at the cap coming from the coil, and each plug has spark.

    Also, there are no codes being thrown.

    Looks to me that the problem resides in the fuel pump. I have a new pump and filter ready to go in, but wanted to get opinions on anything else I need to look at before tearing into it this weekend.

    Give me your thoughts.
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  2. #2
    Registered User opus70's Avatar
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    Sounds right but How about the Fuel filter first?? If its REAL Nasty sounds like that too.

  3. #3
    S.I.C. St Louis slash's Avatar
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    Quote Originally Posted by opus70 View Post
    Sounds right but How about the Fuel filter first?? If its REAL Nasty sounds like that too.
    Thanks man... I changed out the filter while I was under there yesterday. The fuel pump is definitely bad... on a sad note, I am waiting until tomorrow (Tuesday) for a replacement sending unit. The OEM one on there the metal tubes were deteriorating badly, and one of the tubes started spitting gas immediately when I dropped the tank down an inch. So hopefully tomorrow evening we'll know if I got everything fixed.
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  4. #4
    S.I.C. St Louis slash's Avatar
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    Got her running last night at midnight. I hate the tanks in these things. Primed the fuel lines and she ran like a champ. I took it for a short spin and it appears my fuel problem has been corrected. I didn't drive it to work today, but plan on taking it out for a longer drive to see if everything is ok this evening.
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  5. #5
    member 178 ti28's Avatar
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    cool man ya got it running. let us know what happens!

  6. #6
    S.I.C. St Louis slash's Avatar
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    ok, I have fuel again... replaced the filter, pump and sending unit...

    went to take it to work today and she died a mile and a half from the house (as a crow flies)

    Same symptoms as before... truck stalls won't restart for a while, then can drive it for a mile and dies again...

    I am getting a little pissed now, I have my brother checking on a few things for me, but does anyone have a clue???
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  7. #7
    it fell? otter's Avatar
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    ignition control module
    fuel pump relay
    fuel pressure regulator


    You may want to pop the upper intake cover off and see if you have any puddles of gas in your lower intake manifold, the cpi injector assembly is a known trouble area on these vehicles.

    Let me know.

  8. #8
    S.I.C. St Louis slash's Avatar
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    I've got a new ICM, just did not install it yet. My brother said to check the coil also, could be the coil arcing or perhaps the wires in the connector.

    I also swapped out the fuel relay for a new one.

    We'll see what happens tonight after work...
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  9. #9
    Registered User blazzerman101's Avatar
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    i had something happen to me like that. just suddenly died. did everything i could think of. found out it was my EGR. there was a little piece of carbon holding it open a bit. i just pulled it out and cleaned it up with some carb cleaner and it did the trick. not sure if this is the case for you but its worth a try.

    http://www.blazinlow.com/forum/showt...ight=EGR+valve

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