Volvo MD2020B - Trouble Starting

[Nuff]

Hi All ,
Hoping someone has had a similar experience and may be able to help.
I have a Volvo MD2020B in a Roberts Longboat 21 which has been running perfectly . After a 2 week trip (approx 100Hrs running with no worries ) I began having trouble with starting .
To get it to run ,it needs about 3/4 throttle to kick in (before this it would always start instantly at idle) and when it does start it Revs very high then reduces down to an idle than revs very high, continuing this sequence for about 5 minutes until the revs even out again and it idles perfectly . I can then start it at idle again no problems for a few hours afterwards ,but if I leave it overnight it returns back to the same problem.
My first thought was air in the system , but have replaced all fuel lines ,Cav filter and tried bypassing the main filter altogether but have had no luck .
Driving me mad !

Wondering if anyone has had a similar problem ?

 

[Nuff]

Solved the problem , just purchased D1-30

 

[Bilgediver]

Solved the problem , just purchased D1-30

Might have been less costly to fix a broken governor spring or sticking linkage

These 2030 engines are often used to replace older engines and installed in boats where insufficient attention is given to exhaust layout. I have seen a few installed where an amount of the exhausting water can back flow into the engine every time the engine is stopped. This usually makes itself known by poor starting due to valve seat corrosion in the rear most cylinder however this water contamination of the oil could also cause rusting in the governor linkage area if the engine does not reach high enough temperatures and get rid of it.

This situation is easily remedied by using a high rise type exhaust elbow to prevent the back flow. Beta recognised this problem very early on and make such an elbow.

 

[volvopaul]

Sounds like a simple air leak to me. Also this engine family is renown for faulty lift pumps. Buying d 1 won't be the end of your troubles in a few years. It's a Japanese Perkins renown for premature bore wear, poor combustion , injectors failing all Leading to bad starting which is where you already were.

 

[Nuff]

Thanks for your replies , much appreciated .
An air leak was the obvious answer to me as well , but having bypassed all filters and replaced all fuel hoses , even had the local VP mechanic to look at it with no luck .
The next step was to start looking at Governor springs and linkages , Injector pump and so on, but with the mechanics hourly rate and the cost of parts it could have been an expensive project , and once repaired I'd still have a 15 year old motor that may have other problems.
Am aware of the exhaust problems , but thanks for the heads up , will look into that .

Seems to me all brands of these small diesels have their problems , but having read so many forums , most people seem to give the VP D1-30 the thumbs up for quiet smooth running and reliability .

Thanks Again