Engine power surge on MD32A

[lhasa]

Hi all its that Fjord 27 again ! I have a problem at the moment of the engine suddenly accelerating then dropping back again. Its not clutch slip as the boat surges forward, bit of a problem when manouvering! Any ideas?

 

[mchancox]

Hi,
Without seeing or experiencing the surge that you mentioned my first suggestion would be to make sure that the diesel fuel line is secure and that you are not sucking in air along the entire length of your fuel line up to and including the injectors.

See if that helps at all.

Regards,
Mike Hancox,
MCH Marine Electrics.

 

[Divemaster1]

More information about conditions needed, but judging from the last post ...head skimmed etc... Engine serviced, injectors checked, valves ajusted and new filters ?

Does it happen at idle when in gear, at varying RPM's ?

Could it be fuel supply??? ie have anyone tampered with the fuel supply valve whilst engine being serviced ?

Have you checked the exhaust bend ? ... where raw water meets the exhaust at the back of the engine (Knee bend, fixed with 4 bolts to the manifold and a hose connecting for raw cooling water exiting from engine)... This bend often rusts and clogs up causing the engine to be restricted causing similar sympthoms..

 

[Kawasaki]

You say it is a problem when mooring
This suggests the symptom only happens at slow speeds
Is this correct?
Clarify this and maybe a diagnosis can be suggested
It deffo aint clutch slip!!

 

[Andrew_Fanner]

If not slipping bits in the gearbox or an exhaust restriction its fuel related or you could have something round the prop. Does the erratic speed manifast when in neutral at similar revs?

 

[SAMYL]

If the engine is starting and generally running smoothly at whatever revs then it is not air ingress.

If it normally happens at low revs then it is a faulty govenor in the fuel injection pump, it will happen at working revs too but you will not notice it. Have your pump reset etc. by your local injection specialists.

 

[PCUK]

Classic symptom of air ingress. Small amounts building up in the filter and then passing through and clearing before stopping the engine. However, could also be partially block fuel filter although would expect that to happen at speed rather than on tick-over.

 

[lhasa]

Hi, no it tends to do it at various throttle settings. I can be cruising steadily when it will suddenly surge for a couple of seconds then drop back, it can then reoccur a few times or perhaps go an hour before happening again. My wife says it has a malevolent entity in charge of the engine ! Does this sound like a plausible explanation !!

 

[BGW]

Hi, no it tends to do it at various throttle settings. I can be cruising steadily when it will suddenly surge for a couple of seconds then drop back, it can then reoccur a few times or perhaps go an hour before happening again. My wife says it has a malevolent entity in charge of the engine ! Does this sound like a plausible explanation !!

I had a similar problem on one of my old perkins 6-354's.
Countless people told me to send the injector pump in to be serviced, but while doing my engine service I replaced the fuel filter and the fuel lift pump, and it has run perfectly ever since.
The filter looked OK, so none the wiser as to whether it was a small air leak, or fuel starvation, but start simple and work your way up is my advice.

 

[Tugw]

I hate Bl**dy MD32As ive got two of em that make it thier bussiness to make my life hell.

BEST of LUCK

 

[lhasa]

I had a similar problem on one of my old perkins 6-354's.
Countless people told me to send the injector pump in to be serviced, but while doing my engine service I replaced the fuel filter and the fuel lift pump, and it has run perfectly ever since.
The filter looked OK, so none the wiser as to whether it was a small air leak, or fuel starvation, but start simple and work your way up is my advice.

That sounds encouraging. Replacing the fuel filter has been mentioned before so I am going to try that first, along with a check of the fuel lines, and see what happens