30DMH 3 cyliner 2 stroke - failing under load

[mattrw25]

HI,

I have a 30DMH that runs and starts perfectly but when put under full load for am minute or so stutters and looses power. When left to idol for a minute it then runs perfect again. Have checked the fuel and lines which looks okay and have changed the plugs.


I noticed the filter has the fuel drain out whilst running to only be about 20% full. Is that normal?


Any help would be greatly appreciated

[99yam40]

my guess is a restriction or sucking air between the tank and fuel pump,
or the pump itself

[mattrw25]

Thanks 99yam40

Thats what I have been thinking but couldn't find anything obvious. Replaced all the internal lines with no success. I've just replaced the filter (looked pretty deteriorated but couldn't see any obvious leaks) seems to be staying 3/4 full now when running on the trailer. Hopefully that solves it but will have to take it for a run to put it under load and see what happens.

[ausnoelm]

I think a carb clean might be in your future, what did the plugs look like when you changed them?

[mattrw25]

ausnoelm Plugs looked good but changed them anyway to be sure.

[mattrw25]

I’ve just noticed in the handbook that it will limit to 2000rpm if over heating. This would make sense as it doesn’t feel like it’s being starved fir fuel. Anyone have any experience with this?

[99yam40]

does this motor have any indicators of overheat besides RPM reduction?
gauges , lights ,or alarm buzzer?
if so do they work?

Pull stat and test in a pot of water heating while monitoring temp when stat opens and closes to make sure that is in spec for you motor.
water pump kit may be needed and inspect the housing for melting.
replace as needed
monitoring temp of head where the overheat sensor is when problem shows up should help tell if that is the problem