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C32 fuel pressure glitch

Discussion in 'Engines' started by Pascal, Mar 12, 2021.

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  1. Pascal, Mar 12, 2021
    #1
    Pascal

    Pascal Senior Member

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    Got an odd one earlier today... just after leaving the slip at Nassau Harbor Club, starboard C32 (2009, 3500 hours) started running rough at idle on gear and I noticed right away I had no fuel pressure (10 PSI). Engine died a minute later

    left the harbor and anchored off the east end. Checked the obvious (racor valves and tank valves)... I texted my cat guy who replied right away : priming pump

    Unscrewed the pump, pumped a few times, felt fine. Reprimed the engine with electric priming pump, fired right up with solid 50 PSI pressure. Ran flawlessly for the two hours run to Norman’s.

    My Cat guy said priming pumps can fail and block fuel flow. He suggested having a spare on board which I m going to get. It s possible that having used the pump cleared whatever it was

    also possible that a check valve is failing and causing engine to loose prime. I guess I ll see what happens when i start them up tomorrow.

    Anyone ever had a priming pump fail?
  2. NYCAP123, Mar 12, 2021
    #2
    NYCAP123

    NYCAP123 Senior Member

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    Had motors lose prime but never had the pump fail and block fuel flow. That's a new one. But yeah get new and check the old. You can never have enough spares of anything on board.
  3. Capt Ralph, Mar 12, 2021
    #3
    Capt Ralph

    Capt Ralph Senior Member

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    Are those are the old black cased Walbro pumps?
    They are serviceable with a magnet and screen in the bottom.

    A Hatt I worked on had those with the C32s.
    Parallel with the fuel line, opposite from a check valve in the fuel line.
    In this setup, I don't see the pump causing an issue, maybe that check valve if used.

    If it is in line, the pump screen may have had a restriction.

    I recall reed valves and an oscillating piston within a field (voice) coil that made it work.

    I'm still scratching my head, did the pump work before you disconnected it?
  4. Pascal, Mar 12, 2021
    #4
    Pascal

    Pascal Senior Member

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    The C32a have manual priming pumps mounted on a block by the secondaries. Unscrew the handle and then pump it back n forth to reprime. According to the cat guy that s the pump which can restrict flow.

    We also have 4 Electric priming pumps between the tanks and the racors for both mains and gens. The pumps for the mains have a bypass valve so they can’t interfere with flow.
  5. Slimshady, Mar 12, 2021
    #5
    Slimshady

    Slimshady Senior Member

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    My cat dealer said the same thing when we got her new. I carry a spare but have never used it.
  6. Capt Ralph, Mar 12, 2021
    #6
    Capt Ralph

    Capt Ralph Senior Member

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    Oh, the hand plunger pumps.
    Other than some leakers, never knew they were a problem.
    Never knew they could be a restriction in the fuel feed, still must have been a check valve of some kind.
    Way out there, thinking from Mars or there about, if the plunger and top seal got dry, maybe, maybe, maybe some air could be drawn in.
    I'll be doing some more body part scratching over this tonight.

    Of course, glad you got it going.
    I expect a good start in the morning.
  7. Capt J, Mar 12, 2021
    #7
    Capt J

    Capt J Senior Member

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    Yes, I’ve had both the priming pumps and check valve fail. Change the check valve. First it starts doing what you saw and then it fails completely and no amount of priming will make the engine run when it fails completely
  8. Capt Ralph, Mar 12, 2021
    #8
    Capt Ralph

    Capt Ralph Senior Member

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    There is a valve on the 3126s that you have to turn before using the hand pump. Located at the base of the hand pump.
    I have witnessed the seal in it fail and cause problems.
    When I get back to my desk, I'll have to look up the IPB on this and get my mind on track.
    A big expensive C32 can be downed because of a hand primer pump.
    F M
  9. Pascal, Mar 12, 2021
    #9
    Pascal

    Pascal Senior Member

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    Which check Valve and where ? Tech said if the check valve fails complexity and it looses prime, it just needs to be primed with the electric pump...
  10. Capt J, Mar 16, 2021
    #10
    Capt J

    Capt J Senior Member

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    I don't remember exactly and would have to see the engine to see it. I think it was in the secondary filter housing, but wasn't paying a whole lot of attention. But was running a big Princess for a dealer and at first it would lose prime and you'd have to pump the priming pump 50-100 times and engine would start/run......then at the yard it wouldn't start, try to and act like it was air locked.....a few cylinders would fire but wouldn't run. Mechanic came out and changed the hand pump, didn't fix it.......then there was a small check valve and I think spring he changed and fixed the problem the dealer was dealing with ever since they took the boat in trade.
  11. Pascal, Mar 16, 2021
    #11
    Pascal

    Pascal Senior Member

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    Thabks for the info. Did 5 or 6 starts since Friday and no issue since. Still will get a spare priming pump ... these manual pumps take forever. Having electric pumps is such a time saver after a filter change