Powerpack for a 4.3l Chevy

Discussion in 'Gas Engines' started by Caper7, Jul 11, 2016.

  1. Caper7
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    Caper7 New Member

    I have an '87 SeaRay Seville with a 4.3l Chevy engine. The boat will start and purr nicely, then will quit and not want to start. Mechanics think it is the ECU/Powerpack and tell me it costs $1100 (CAN). Will a car part fit safely?
     
  2. PAR
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    PAR Yacht Designer/Builder

    Welcome to the forum.

    Well, the mechanic should know for sure, not be guessing, especially considering the price. The early OBD1's are pretty basic, so back tracing issues is fair easy. In fact (I'm not completely sure) in 1987 the very beginnings of OBD1, when a standardized 16 pin plug started showing up, followed by CARB, but it's probable you have the old ALDL protocol and who knows what was used.

    In any case, you likely have the 10 pin jack and your mechanic should be able to hook up and diagnose the issue(s). If he can't, you need to find someone that can. On your system it's an integrated PCM, which varied considerably across engine and platform families. Simply put, nope, you can't just slap a new one in there, it needs to be matched up.

    All this is generic stuff, what you need are specifics like; which tests have been preformed and what their results are. What are the symptoms before, during and after the no start scenario, etc. To be honest, I think you have the wrong mechanic. There's a series of inspections, evaluations and tests that typically can be preformed, usually in a sequence, so you can track down and pinpoint problems.
     
  3. gonzo
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    gonzo Senior Member

    I agree. The mechanic should be able to be positive about whether the module is good or bad. Ask him if he guarantees that it is the problem or you get your money back.
     
  4. PAR
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    PAR Yacht Designer/Builder

    The old ALDL boxes can be hard to diagnose, if you're not familiar with them. The technology changed rapidly in this era, so protocoles, connectors, etc. also changed. This requires some adapters and some understanding.
     
  5. Caper7
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    Caper7 New Member

    Thanks for advice. Sadly, we did install a new CDI (not sure if Power Pack is the right term) but boat still:
    -Starts, idles, putts along
    -Runs rough when throttle is applied with any vigour
    -Then cuts out and won't start.

    I'm pulling my hair out on this one, most persistent mechanical problem I have encountered. Thanks again for any advice you can give.
     
  6. gonzo
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    gonzo Senior Member

    Did he do the basic mechanical tests: compression, fuel pressure, timing and advance, running temperature?
     
  7. PAR
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    PAR Yacht Designer/Builder

    Again, you can hunt and pick, replacing suspected parts as you go, which is a really expensive way of doing things, OR you can actually find the problem, repair or replace the defective part(s) and move on. I guess it's a good thing this wasn't your doctor, as this diagnostic approuch could be painful, right . . .

    As a rule the ECU/PCM assemblies are very robust and reliable. They last decades and usually don't fail, but do eventually develop connection issues at its interfaces (bad connector pins). There's a sequence (again) you go through to find problems. What's it missing, spark or fuel? Is it getting a fuel signal (EFI), is the pump running, is the pump at pressure, has it been checked on either side of the regulator? There's literally a few dozen things to check and with each test, you're lead in a specific direction in which to further proceed. Find a mechanic that has a clue, before you start buying more parts.
     
  8. keith_2500hd
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    keith_2500hd Junior Member

    what engine does it have, mercruiser, omc cobra or Volvo. should be carbed, 2bbl or 4bbl, maybe 2gc, quad or holley depending on manufacturer. you need to check spark, compression and timing movement; advance and fall back.
     
  9. PAR
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    PAR Yacht Designer/Builder

    Keith, it's stated above, a 1987, 4.3l Chevy, which would have used a TBI (LB4) or a quadrajet (LB1). The TBI engines have a ALDL style ECU/PCM, while the carbureted version have conventional controls. This particular engine should have the one piece rear main, but no counter shaft, which came later to the 4.3. I agree the problem should be simply a matter of tracking down the symptoms and working through the diagnostic process.
     
  10. keith_2500hd
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    keith_2500hd Junior Member

    marine is different from automotive, not aldl. car wont have proper timing. mechanic stating ECU/power pack, it must be an OMC Cobra drive, not mercriuser or Volvo-penta. cheap alternative would possibly be to install DUI(Davis Unified Ignition) marine distributor(GM HEI modified to spec's. boat engines fall within heavy truck setup more then car when looking for and using components. GM engines for boats come out of industrial engine division. OBD was not used in boats until 2010 OBD-M. some of the early mercruiser efi modules are no longer made and require later module and harness the configure and are expensive due to added engineering.
     
  11. PAR
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    PAR Yacht Designer/Builder

    The earliest MEFI units I've seen where in the early 90's (1992, I think it was) and this was pretty primitive ALDL connected PCM units. I have a '97 Mercruiser MEFI-2 MK4 hanging on a lift right now. All of the early EFI setups I've seen on Mercruisers, have had the port hidden, capped and wrapped into the harness.
     

  12. keith_2500hd
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    keith_2500hd Junior Member

    while they look like auto MEFI's, they were password locked. you could use MEFIBurn to access programing. MEFIBurn has a list of passwords to hack. a marine or industrial may work on automotive engine, but an automotive MEFI will not feed enough fuel for the marine/industrial engines. you can buy code reader from rinda, an automotive can't be used to do the same.
     
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