1984 90 V4 loses power at WOT

[Larry Engelbrecht]

Hello all. Friend's Evinrude starts right away, idles with occasional miss, misses a LOT under throttle. Ran great last year, plugs and wires good, carb was cleaned and kitted last year, appears clean from outside. He said problem started this year, added 6 gallons with no change. Squeezed primer bulb at idle and WOT with no change. I hadn't tried using choke while running but did spray brake cleaner into air inlets - engine slowed down. Boat has built-in fuel tank and we do not have separate portable tank, so how would you suggest I try to feed motor fresh gas to see if tank has bad gas...or is this indicative of varnish in the carb? Thanks in advance.

 

[Joe Reeves]

Re: 1984 90 V4 loses power at WOT

If you're going to spray anything into that engine, use premix in a spray bottle. Have carburetor face plate off and with engine running and acting up, spray directly into the carburetor throat.

If you have compression and proper spark on all cylinders, I'd suspect that the brass high speed jets, located in the bottom center portion of the float chambers, are somewhat fouled and need cleaning. You can do this with a piece of single strand steel wire.

To test carburetors for fouling.... with engine running and at the speed where they're actin up, simply stick two fingers into the carburetor throat, acting as a manual choke of sorts. If the engine has a tendency to smooth out and the rpms pick up, you've found a offending carburetor.