No power under load

[rikclark]

On my last outing over this past holiday weekend I had the followoing experience with my '86 150 2-stroke. Started fine, idled smooth, but once in gear, engine "sputtered", run very rough, and I could not get it above 1500 RPM. Could not get the boat on plane.
When I shift to neutral, the engine smooths out and will idle smoothly at any RPM setting when revved with the fast idle lever. But again, once in gear and there is a load on the engine, there is a significant loss of power with the engine acts like it is fuel starved.

First time I've had this problem with an engine I've owned since new and has provided exceptional reliability. Any suggestions regarding diagnostics or repair will be appreciated.

[callum]

same problem

Hi, from scotland.
I think the problem might be the diaphragms.I have just
stripped my carb down and I saw that the main diaphragm which is made of
silicon or rubber was badly strethched into a belly bulge this might cause the
problem as it has reached the limit and wont draw anymore petrol into carb.
I phoned for replacements and he had sold the last ones,but reorders them
automatically.I am hoping this means that it is a common occurrence.
I hope to get them today,I will let you know as soon as I can.
your engine 150 etj 1998 if so, I have a parts manual showing carb .
be in touch. Callum

[mlhilla]

Pls. don't be insulted by this one. Every once in a great while I encounter this and find 4" - 6" of "stuff" growing on the bottom of a hull that hasn't been out a lot. Rare, but when the engine checks out good, the issue has to be somewhere!
Good luck!

[callum]

Hi, again just finished fitting new diaphragms and a gasket. This has helped as they needed changed but I noticed that the
petrol filter was missing after seeing some dirt in petrol tank.I will fit an inline filter and clean out carb. here's hoping