28HP Johnson kills at full throttle

[Larry_C]

I friend of mine has a '97 28HP Johnson with oil injection on a pontoon. Runs fine except stalls
at full throttle ... appears it is not getting
gas. Any ideas??

[Bob Z]

I had a similar problem with a Merc that 'cut out' and ran very rough at high speed. Found a small hole in the fuel pump diaphragm.

[minneman]

Ditto, bob z, check the diaphram, and if he lenghthend the fuel line for any reason, that may be why it failed. minneman

[John]

The 28 Johnson isn't an oil injected engine, but OMC offers an oil mixing unit called an Accumix-R, there's a slim possibility there'e a restriction in it or, the engines fuel pump isn't up to snuff as far as pulling fuel thru the Accumix-R. The other posibility is a wire getting pinched (grounded) when the linkage is advanced to WOT.

-John