1997 AD41P seems to lose a cylinder when running at high rpms and will only pull 3600rpm

Hi everyone,

This is my first post as a junior member. I have a 25' Botnia Targa, a boat built in Finland. The boat is a 1997 model fitted with a AD41P and sterndrive. I have some concerns that there is something slightly wrong as I can only pull about 3600rpm at WOT. Also, if you leave the throttle open it feels like there is a misfire or hesitation. Does anyone have any ideas as to what could be happening? Could I have a dodgy injector or pump, in which case how do I check this? The engine temperature seems fine.

many thanks

Steve

Re: AD41P seems to lose a cylinder when running at high rpms and will only pull 3600rpm

Hi, I have a similar problem with a 42b dp in a 9.9m alloy commercial crab boat.
Was working fine, developed a "miss" at high speed which slowly got worse over time, yesterday we only got 2000rpm max but still runs smoothly and beautifully up to 2000rpm.

Generally means that there is a problem with the fuel delivery.

Rebuilt all fuel delivery system from fuel tank all the way to the injector pump, our lift pump was worn out (on the side of the block, port side, under fuel (secondary) and oil filters) so we just bypassed it with an electric unit ("faucet" brand, $60. against about $1200 for a genuine pump)

This fixed most of our problem. Our racor was perforated allowing heaps of air into the fuel system so it was replaced with a universal fit water separating filter at much less cost than a genuine racor to do the same job. (just make sure it can flow enough fuel through at high revs)

Another theory we have with ours is the fuel injection timing seems to be retarded. I'm just looking up how to adjust this, or it could be a damaged injector tip (or two) which would mean an expensive repair bill because injectors have to be bought from volvo.

Worst case scenario would be a perforated governor diaphragm because this is the final "pump" in the fuel delivery system and would involve disassembly of the injector pump. Costly because of the labor component, governor parts seem reasonably priced (about 20 euros or so for diaphragm)

Hope this helps, I'll post the results of today's tests in case they're relevant to your case.

If you don't mind, what model Facet pump, or what Gallons per Hour rate did you select. Perhaps I'm soon to have the same need. Any recommendations?

pv

Another theory we have with ours is the fuel injection timing seems to be retarded. I'm just looking up how to adjust this, or it could be a damaged injector tip (or two) which would mean an expensive repair bill because injectors have to be bought from volvo.

If the injectors are bosch, any bosch pump shop should be able to service them. You will be able to save some money.