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Thread: Mechanical fuel (lift) pump issue

  1. #1
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    Default Mechanical fuel (lift) pump issue

    We replaced the mechanical fuel (lift) pump on our '84 probably 4-5 years ago for a leak where it's swedged together. We replaced the old pump with an AC Delco 43254, which is now beginning to leak around the swedge as well. Anyone have any experiences or suggestions on a better quality pump? Maybe I just got a bad AC Delco one?
    Bob

    '83 K2500, 6.2L J-code, NV4500, NP208, 3.73 gears

  2. #2
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    The pumps have a weep hole near the bottom of the pod (near the swage). If they leak there, the diaphragm is ruptured.

    Delco is the better pump, but that doesn't mean they won't fail. It's possible older pumps don't like modern fuels, especially if bio/veggie is in the mix. Modern pumps should be manufactured to tolerate this much better (logical), but I don't know that for certain. I went rounds with aftermarket pumps with long warranties, which were honored, often. Replacing pumps isn't difficult, just time consuming and very inconvenient. We can choose when to replace them, but we don't get to choose when they fail. Years ago, I looked into an aftermarket repairable pump (don't recall the brand, but it was a national label) with a replaceable diaphragm. It looked like a nice setup, as they could be repaired without removing it. The repair kit was around $10, as I recall. I'm glad I didn't go that route, as they were vapor before the current pump at the time failed.

    Ultimately, just get good at replacing them, if you're keeping old iron. If quality pumps are failing at a high rate, look at manufacture dates and/or your fuel source. Electric pumps are an option, but IMO, don't last longer or work better, but may be easier to service, and offer operation without cranking the engine. The best I can offer is a little advice. Use some axle grease on the push rod to keep it up during the install, and make sure the lever doesn't slip along side the push rod before tightening.
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

  3. #3
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    Thanks a lot for the information. Sure appreciate it.

    I came across the Delphi HFP906 mechanical pump for the 6.2L. I thought about trying that one, but heard it might be the same pump as the AC. Have you heard anything on the Dephi?
    Bob

    '83 K2500, 6.2L J-code, NV4500, NP208, 3.73 gears

  4. #4
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    I don't know. Delphi is another GM supplier, often the same or comparable with Delco. I'd be more concerned with mfg dates and/or country of origin (difficult with online orders), but I'd choose this pump over any aftermarket brand.
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

  5. #5
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    Gotcha. Thank you.

  6. #6
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    I thought Delphi was the spin off of GM's ACDelco business, but I guess it ain't that simple...
    The Constitution needs to be re-read, not re-written!

    If you can't handle Dr. Seuss, how will you handle real life?

    Current oil burners: MB GLK250 BlueTEC
    New ride: MB GLS450 - most stately
    Gone but not forgotten: '87 F350 7.3, '93 C2500 6.5, '95 K2500 6.5, '06 K2500HD 6.6, '90 MB 350SDL, Kubota 7510

  7. #7
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    I don't know, exactly. Used to be, on older vehicles (50's-70's), AC Delco was engine electrical and ignition, while Delphi was body/chassis electrical and early electronics, like radios and clocks, but they crossed lines with some, at least on GM vehicles. Or so it seemed at the time. AC Delco was almost exclusively a GM supplier, while Delphi was a GM company that supplied nearly all brands internationally, including aircraft. Just going off memory, but I suppose I could look it up.
    1985 Blazer 6.2
    2001 GMC 2500HD D/A
    dmaxmaverick@thedieselpage.com

  8. #8
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    Most of ADC parts are manufactured in China. They are very nicely made, but it's what's on the inside that counts. Carter makes an alternative for the GM part, but be careful about fuel pressure. The stock inlet fuel pressure supplied to the fuel injection pump should be in the 7-psi range.

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