Volvo Penta MD22P - Flat Spot

[miyagimoon]

Our MD22 has what I can only describe as a flat spot. Through out the revs range except 1100 - 1400 rpm it will stay at the required revs. But if I back it down to 1400 rpm it will hold for a short period say 30 seconds then the revs will drop back to 1100 rpm. If at 1100 rpm I try increasing revs it will only go to 1400 and above. No matter what I do or try with the throttle control it will not sit between 1100 & 1400 rpm. It only happens when in gear (I have never tried it in reverse) it does not occur when in neutral.

Any body else suffered this and if so how did you cure it.

 

[RichardS]

Is it actually a flat spot in terms of engine firing or is it slippage in the control cable system? You could watch the governor lever on the side of the engine and see if that moves when the revs drop.

Richard