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Thread: Initial Hard start/NO start 7.4 Merc Cruser w/carb

  1. #1
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    Default Initial Hard start/NO start 7.4 Merc Cruser w/carb

    My 7.4 V8 Merc Cruser with carb is almost impossible to start without using a shot of starting fluid if I let it sit for a week. Overnight it starts fine but if I let it sit between weekends I have to give it a shot of starting fluid and it starts immediately and then runs great. Any ideas or suggestions and no getting fuel injection is not one of them...HAHAHA! Thanks much for any ideas or suggestions

  2. #2

    Default Exact same problem

    Mine does that exact same thing,
    AQ125A Volvo Penta with single Solex 44P-A1-4 Carb
    I'v been just living with it????

  3. #3
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    Default I even tried butterfly adjustment

    I tried closing the butterfly on it thinking it might not be getting enough fuel or too much air on a cold start. Same results. I'll keep searching and hope someone has a suggestion or cure.

    Thanks much piranha

  4. #4
    Member SusitnaAk's Avatar
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    Default

    Sounds like your carb is bleeding out .maybe time to rebuild it?

  5. #5

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    I think SusitnaAK hit the nail on the head. I had the same problem with my 302 Kodiak -- the carb was losing it's prime. I rebuilt the carb (well, I didn't, but Professional Marine did) and then the thing ran like a raped ape! The rebuild also took care of a bit of hesitation, too.

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    Default Similar story on a truck

    My 1995 chevy 350 did a very similar thing to what you state. Granted it was a TBI setup, it turns out that it was a vacuum leak from below the injectors... Instead of sucking air through the carb, it would suck it through the leak (where the carb mount meets the intake manifold..) and would start every once in a while cold, but starting fluid was the solution when it wouldn't start..

    It kind of does sound like a carb prime issue though... When was the last time the carb was rebuilt? It can sometimes take a lot to get the prime back to the carb. The engine running (on starting fluid) creates a lot more suction than the starter turning it over does!

  7. #7

    Default My vote

    Is for a carb rebuild. Although, you may have a vacuum leak elswhere. Try spraying the starting fluid on the intake and carb gaskets while it's idling. If the idle picks up, you found your leak.
    We never really grow up, we only learn
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  8. #8
    Member fishnngrinn's Avatar
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    Default hard start

    Carb is losing fuel when it sits. A friend of mine solved this problem by installing an inline electric fuel pump to prime it. The pump is shut off when the fuel line is pressured up. Better to prime with petrol than with ether.
    NRA Lifetime Member

  9. #9
    Member Dupont Spinner's Avatar
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    About impossible for a carb to lose prime(??????) unless the fuel is evaporating because of heat, then I would worry where the fumes are going, or the carb is leaking into the intake (pull the dipstick and smell the oil) or ?????. If the mechanical fuel pump is losing prime then you may have a pinhole in the pump membrane. A weeks time is way to quick for fuel to bleed off with out some type of mechanical issue or problem fuel pump. Depending on year you actually may have a manual and electric pumps in series.

    So your choices are going to be the rebuild and/or base gasket. Also like stated above spray some of that starting fluid at the base of the carb to check for leaks, also spray along the intake on both sides. If no change in idle rpm then focus on the carb.

    I am going to guess at a Holley Carb....I know you said no fuel injection, so how about putting on an Eldebrock Carb. If you decide to get the Edle, do get then tuning kit. If it has the Rochester Carb may be time to disassemble and clean it out.

  10. #10
    Member Rod in Wasilla's Avatar
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    Check out this thread on iBoats. He had similar symptoms.
    Quote Originally Posted by northwestalska
    ... you canít tell stories about the adventures you wished you had done!

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    Default thanks much all of you!

    I appreciate the help and input and now at least I have a few htings to try....Sounds like a carb rebuild may be in order......but I will try all of your suggestions.....that is why I really appreciate this forum! Great people here!

  12. #12

    Thumbs up Let us know

    What you find.
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  13. #13
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    Default

    Well it turned out to be a carb rebuild.......now it starts...no prob

    thanks to everyone!

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