david_bagshaw
Well-Known Member
A long shot...
have you checked the throttle/ governor lever moves when in gear?
what happens in reverse?
have you checked the throttle/ governor lever moves when in gear?
what happens in reverse?
Engine won't rev
- Thread starter Graham_Wright
- Start date
roaringgirl
Well-Known Member
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.
Daydream believer
Well-Known Member
Graham_Wright
Well-Known Member
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-...rentrq:8f3f98d916c0a861b6bb24a9fffca682|iid:1.
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.:ambivalence:
Graham_Wright
Well-Known Member
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.
roaringgirl
Well-Known Member
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?
CAPTAIN FANTASTIC
Well-Known Member
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.
Graham_Wright
Well-Known Member
The engine turns the gearbox with gear engaged but shaft disconnected without problems.
bristoljim
Well-Known Member
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
Jim
Graham_Wright
Well-Known Member
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!
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!
bristoljim
Well-Known Member
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
Jim
bristoljim
Well-Known Member
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
Jim
Graham_Wright
Well-Known Member
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/faq/131000-bmc-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.
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bristoljim
Well-Known Member
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
Jim
Iliade
Well-Known Member
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.
black mercury
Well-Known Member
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.
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.
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Graham_Wright
Well-Known Member
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.
lw395
Well-Known Member
Sounds like there was air in the system?
Graham_Wright
Well-Known Member
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.
black mercury
Well-Known Member
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.
