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  1. #31
    Join Date
    Dec 2008
    Posts
    147

    Default Re: Engine won't rev

    Lift pump pressure is delivered by a spring in it,the lever on the cam or hand lever just resets the spring so if flow is restricted the pressure will not exceed what the spring can generate.Check that the two pipes from injector pump to CAV filter are connected the same on your two engines
    Jim

  2. #32
    Join Date
    Dec 2008
    Posts
    147

    Default Re: Engine won't rev

    The lift pump pressure is produced by a spring in the pump - the lever on the cam & the hand lever resets the spring so if the flow is restricted the pressure is limited to what the spring will generate.Check that the two pipes from the injector pump to the CAV filter are connected the same on both your engines.From memory the two pipes back to the filter was the standard 1.5 system with a restricted bleed off the top back to tank
    Jim

  3. #33
    Join Date
    Dec 2002
    Location
    Gloucestershire
    Posts
    5,384

    Default Re: Engine won't rev

    Quote Originally Posted by bristoljim View Post
    Check that the two pipes from the injector pump to the CAV filter are connected the same on both your engines.From memory the two pipes back to the filter was the standard 1.5 system with a restricted bleed off the top back to tank
    Jim
    Now that's interesting. The spillover from the injectors, series connected as it were, terminates at a "double-eared" banjo connector on the filter. However, the stud attaching the banjo to the filter is blind. I have wondered why this is so. There is very little spillover anyway and that exits from the banjo very infrequently.

    I've tried to add a shot of the arrangement from the ASAP on-line manual but it exceeds size limits.

    https://www.asap-supplies.com/media/...1.5-manual.pdf

    section 50D clearly shows the return to the filter. It also shows the double eared banjo connector with a pipe leading off downwards.
    Last edited by Graham_Wright; 16-08-19 at 11:37.
    I'd rather be naked
    www.mastaclimba.com

  4. #34
    Join Date
    Dec 2008
    Posts
    147

    Default Re: Engine won't rev

    The banjo bolt restriction hole is quite small just enough to let small amounts of air back to the tank with the injector leak off
    Jim

  5. #35
    Join Date
    Apr 2005
    Location
    Shoreham - up the river without a paddle.
    Posts
    1,225

    Default Re: Engine won't rev

    I had a very similar issue with my 4108 recently (also has a hydraulically regulated governor.) Changed filters, cleaned diesel bug goo from water traps and added bug killer. Bingo! Immediate restoration of normal service.

  6. #36
    Join Date
    Jun 2013
    Location
    scotland
    Posts
    205

    Default Re: Engine won't rev

    After reading and re reading post 30 I think I understand that you supplied the injection pump direct from jam jar but with the pipe now removed from the filter to the injection pump and the outlet from filter was left unconnected, you got fuel gushing from the open connection. You then blanked this, is that correct? Then you tried the engine which was now revving higher. You seem concerned about the fuel return going to the filter, but that is the way the engine has always been, so I don't see that as a problem, there should be a return line from the filter to the tank, any excess going down this line. You can't over pressurize the injection pump, it has a regulating valve in the fuel inlet, you will see it in the manual, unless it goes faulty.
    I would leave the connections on the filter as they are, but run a pipe from your electric pump (which seems to be working ok) direct to the injection pump. Try this, the fault may be in the mechanical lift pump which may need dismantling. Basically you want to bypass the mechanical lift pump.
    Last edited by black mercury; 16-08-19 at 17:44.

  7. #37
    Join Date
    Dec 2002
    Location
    Gloucestershire
    Posts
    5,384

    Default Re: Engine won't rev

    Quote Originally Posted by black mercury View Post
    there should be a return line from the filter to the tank, any excess going down this line.
    There is no such line. Don't understand that! Does that not mean that the lift pump is delivering in vain? In from the pump straight back to the tank?

    Anyway, I have taken the bleed outlet from the injector pump straight back to the tank and the engine will now rev in gear. I have not done an open water trial as I am on the canal and the wind is stiff. I don't want to take out a bridge by drifting down onto it - it is frowned upon.

    I shall report back to the pump rebuilder today and see if he can explain the difference.
    I'd rather be naked
    www.mastaclimba.com

  8. #38
    Join Date
    May 2007
    Posts
    38,226

    Default Re: Engine won't rev

    Quote Originally Posted by Graham_Wright View Post
    There is no such line. Don't understand that! Does that not mean that the lift pump is delivering in vain? In from the pump straight back to the tank?

    Anyway, I have taken the bleed outlet from the injector pump straight back to the tank and the engine will now rev in gear. I have not done an open water trial as I am on the canal and the wind is stiff. I don't want to take out a bridge by drifting down onto it - it is frowned upon.

    I shall report back to the pump rebuilder today and see if he can explain the difference.
    Sounds like there was air in the system?

  9. #39
    Join Date
    Dec 2002
    Location
    Gloucestershire
    Posts
    5,384

    Default Re: Engine won't rev

    Quote Originally Posted by lw395 View Post
    Sounds like there was air in the system?
    No air! I have an air interceptor in the feed to the injector pump and it is clear.

    The various photos I have found on the net, show only three connector to the fuel filter. Fuel in, fuel out and return from the injector pump (plus the injector bleed line which just seems to use the filter as a tethering point).

    Although I am happy that the problem seems to be solved, I would still like to understand why the engine cannot rev with the lines connected as normal.

    I could return the connections as before and see if the problem returns.
    I'd rather be naked
    www.mastaclimba.com

  10. #40
    Join Date
    Jun 2013
    Location
    scotland
    Posts
    205

    Default Re: Engine won't rev

    The return line from the injectors should go to the filter head, and a pipe from it back to the tank. There should be a banjo bolt there with a small hole in it to take excess fuel back to the tank. I believe in a previous post you said this was a bolt with no hole in it. It shouldn't be. Check this out, or take bolt to the diesel shop where they should have the proper bolt.

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