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  1. #21
    Join Date
    Jun 2001
    Location
    uk
    Posts
    2,323

    Default Re: Engine won't rev

    A long shot...

    have you checked the throttle/ governor lever moves when in gear?

    what happens in reverse?
    David

  2. #22
    Join Date
    Nov 2014
    Posts
    62

    Default Re: Engine won't rev

    The engine revs freely without the resistance offered by the prop (in neutral). The engine is managing to turn the prop, but not as fast as you would like, and you can't turn the propshaft by hand. Sorry, but the prop/external shaft is either fouled or damaged. Try to keep engine use to a minimum and dive on it as soon as you can to confirm the problem. If you're lucky it's just fouled and you can clear it with hand-tools.

  3. #23
    Join Date
    Oct 2012
    Location
    Southminster, essex
    Posts
    9,316

    Default Re: Engine won't rev

    Quote Originally Posted by roaringgirl View Post
    The engine revs freely without the resistance offered by the prop (in neutral). The engine is managing to turn the prop, but not as fast as you would like, and you can't turn the propshaft by hand. Sorry, but the prop/external shaft is either fouled or damaged. Try to keep engine use to a minimum and dive on it as soon as you can to confirm the problem. If you're lucky it's just fouled and you can clear it with hand-tools.
    #14
    It is all down to the fact that my wife does not understand me !!

  4. #24
    Join Date
    Dec 2002
    Location
    Gloucestershire
    Posts
    5,351

    Default Re: Engine won't rev

    Quote Originally Posted by black mercury View Post
    Before condemning the injection pump and removing it, get yourself a small container of clean diesel and pipe it directly to the fuel intake of the injection pump, a priming bulb in the fuel line would make things easier. Then try the engine. Yes fuel will return to the main tank and not your temporary container but it will give you enough time to determine if the pump is at fault. You may have symptoms of fuel starvation, using the container will take the fuel supply and filters out of the equation. Also some pumps may have a small wire gauze in the intake pipe at the injection pump, take pipe off and have a look, you probably don't but just to make sure. If you can't get a priming bulb just pipe it without one, the dpa has its own supply pump.
    A canal neighbour has suggested the same thing. I have assumed that, as there is an electric pump supplying pressurised fuel to the lift pump vigorously as a loosened joint confirms, there is no fuel shortage. This may be wrong. It is easy to arrange a feed directly to the lift pump and I will do that. The electric pump does not perform as it used to. Having developed pressure, it used to stop pumping. It now continues albeit more slowly. I have ordered a replacement;-
    https://www.ebay.co.uk/itm/HRF-013-p...a682%7Ciid%3A1.

    It is listed at £13.29 post free. (It looks suspiciously like the one offered by ASAP for considerably more).

    I have tried shifting the timing of the pump. Access is very difficult for several reasons. The pump is secured on three studs. The bottom one is almost impossible to see and there is little room for a spanner. Removing the oil filter housing makes a big difference. I have modified a spanner with thinned sides which makes it possible. The real problem arises from the stiffness of the fuel pipes. They all fight rotation of the pump.

    I have also butchered a 1/2" ring spanner rewelded so that the ring is at right angles to the length. It has a slot cut in the to embrace the pump return line and allows access to undo it.

    I include detail here as a possible help to others who may have the same problem.

    The stop lever is attached to its shaft with a No. 10 unfortunately hex-headed screw which is around 3/8" long. It was loose, and trying to add a washer resulted in it disappearing "below". I replaced it with a socket head screw which allowed the use of an Allen key and made the impossible possible. There are identical screws on the top of the fuel return from the pump. Hex headed screw with little chance of applying a flat spanner. As the screws are so short, they need to be pushed into the female threads to get them to engage. This precludes the use of a socket. Filing a groove across the head made it possible to use a straight bladed screwdriver.

    Sorry to be so verbose but it may help others (and it may help me when I have forgotten what I tried!).

    I have not removed the air filter but it is easy (it used to fall off) and that is a simple one.

    More and more I am inclined to believe fuel starvation but it would help if I understood more.
    I'd rather be naked
    www.mastaclimba.com

  5. #25
    Join Date
    Dec 2002
    Location
    Gloucestershire
    Posts
    5,351

    Default Re: Engine won't rev

    Quote Originally Posted by david_bagshaw View Post
    A long shot...

    have you checked the throttle/ governor lever moves when in gear?

    what happens in reverse?
    The governor is not visible but the throttle lever certainly moves both locally and remotely from the helm.

    When the boat was craned in and the mast restepped, the rigging was slack and so were the guardrails. The yard advised the the hull was now supporting the keels whereas it was the other was round when the boat was on the hard (for many years!) and the rigging was fitted.

    I have assumed that the Aquadrive has taken up any difference in alignment of the cutlass bearing (which is quite long) and the engine but I could be wrong. A lift-out would prove that but cost advises against. When I dry out somewhere, the evidence may present.

    Ahead and astern performance is the same.
    I'd rather be naked
    www.mastaclimba.com

  6. #26
    Join Date
    Nov 2014
    Posts
    62

    Default Re: Engine won't rev

    I see you have checked for a fouled prop and confirmed you can turn the shaft by hand. Then as you say, it's a problem with the engine. Did you say it revs up happily when it's not in gear?

  7. #27
    Join Date
    Jul 2009
    Location
    South Wales and Bristol Channel, UK
    Posts
    2,484

    Default Re: Engine won't rev

    If the propeller shaft turns by hand easily and if the engine revs when out of gear then I suggest that you check the gearbox.

  8. #28
    Join Date
    Dec 2002
    Location
    Gloucestershire
    Posts
    5,351

    Default Re: Engine won't rev

    Quote Originally Posted by CAPTAIN FANTASTIC View Post
    If the propeller shaft turns by hand easily and if the engine revs when out of gear then I suggest that you check the gearbox.
    The engine turns the gearbox with gear engaged but shaft disconnected without problems.
    I'd rather be naked
    www.mastaclimba.com

  9. #29
    Join Date
    Dec 2008
    Posts
    146

    Default Re: Engine won't rev

    Ref your 2000rpm no load observation. A bmc1.5 will normaly rev to 4000rpm no load.It requires very little fuel to achieve any rpm no load.After looking at the drawing of the pump it is the transfer pump inside the pump which generates the fuel pressure for the hydraulic governor. It is not injecting enough fuel to do any serious work. Problem with the governor or other fuel restriction.If it starts & runs there is not a lot wrong with the timing
    Jim

  10. #30
    Join Date
    Dec 2002
    Location
    Gloucestershire
    Posts
    5,351

    Default Re: Engine won't rev

    Further visit yesterday to try the suggested solutions.

    A direct fuel feed to the lift pump from a special fuel tank (jam jar held high);- no difference.

    Same fuel source direct to the injector pump;- exciting. Having removed the feed pipe from the engine mounted filter, I left the bleed return from the pump connected to the other input to the filter. I didn't think it through and the return bleed from the pump exited the filter with some force.
    I then blocked the exit from the filter and tried again. The engine raced, and in gear, the revs ran to 1000 before rushing below to shut off the engine. That implies that the lack of a freely spinning shaft and prop is not the cause of the problems. The boat was moored and I didn't have time to see if she leapt forward more enthusiastically.

    Thinking of the consequences, blocking the exit from the filter (where the original feed was connected) meant that the bleed outlet from the pump was blocked which presumably means that the pre-pump is delivering fuel to the injector pump at higher pressure than normally.

    However, returning the bleed outlet to the filter surely means the same thing. It seems to me there is a closed circuit;- from the lift pump through the filter, to the pre pump, through the bleed-off relief valve and back to the filter. The lift pump prevents back feeding.

    I called in at the injector pump refurb premises in Cheltenham on the way home and discussed the situation with them. They are respected experts with an impressive load of equipment. They agreed with all the procedures I had performed and stated that the bleed outlet from the pump is usually returned to the tank but feeding back to the filter inlet is also common.

    Next visit I shall return the bleed to the tank. I continue to not understand how the aforementioned short circuit can work. That was how the return was connected when the engine was first acquired and that is the same on the spare engine I now have.

    I am sure an expert here will understand.

    Incidentally, the jam jar was filled from the outlet of the first fuel filter which is supplied from the electric pump. It took around 10 seconds to fill the jar. I think it can be said it works!
    I'd rather be naked
    www.mastaclimba.com

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