Engine Throttle Control Fault

[Streetcar]

Thanks for the helpful replies. I've done some more research.

Max Prop say it is possible that an older prop might have a sticking point which could cause it to be trying to 'paddle'. This would put significantly more load on the engine and prevent it from revving properly. However they also say that there would be lots of prop wash and (as someone else mentioned), you'd hear the engine labouring. So this seems unlikely.

I am propbably now going to remove the injection pump off and send it off to be tested and cleaned.

I also note the comments about the lack of lubrication in diesel fuel now. What is a good additive? I didn't understand 'cycle oil'.

[Streetcar]

Problem solved!

Postscript which might be useful to others...

After replacing all engine throttle/gear control mechanism and cables, contemplating the possibilities of gearbox and propellor causes, I had the injection pump removed and sent to Bosch in Lisbon for stripping, cleaning and checking.

They found the pump was clean, but that various parts within the pump were worn beyond tolerance. THey replaced these and rebuilt the pump. It was their view that these worn parts could have caused the problem that I was experiencing.

I have run some considerable distances under engine since then and no further problems.

Bosch expressed some surprise that the pump had been 'apparently' sent for rebuild in 2007 (when the whole engine was rebuilt by a reputable UK Volvo Penta agent).

Anyway, credit to Wavetech in Cascais, Portugal for their diagnosis and speedy turnaround. And thanks to the forum, of course.

[Streetcar]

...and hats off to Daddle for a correct diagnosis some time ago...

[S/V Antares]

Thanks for posting the solution! Also for mentioning the folks who serviced the pump.