Hunting surging at idle

[rock1]

Hi, the LD28 in my boat has started hunting, surging at idle. The fuel filter was changed around 3 months ago and has only done 15 hours running at max. I would be very grateful for any ideas. Thanks Pete [/b]

[Carimbo]

Have you checked for air leak in the fuel path pre-IP? Presuming your marine application does not have an external lift pump, other than the one inside the IP.

[rock1]

I have had a quick check but will look again when I am down there next. It only does it sometimes and only after its been running for a while. it doesn't seem to do it when its cold. Thanks Pete

[dieseldorf]

Does it smoke a lot when its surging?
Engine may suck in and burn oil from intake due to large blow-by.

[rock1]

Thanks, no it doesn't smoke at all and is only doing it sometimes so it has got me stumped.