1987 Evinrude 88hp surges about 4-500 rpm at high speed

[nburford]

When running at 4000 rpm, the engine intermittantly surges around 4-500 rpm, returning to 4000 after a few seconds. Also, the fuel bulb does not firm up when pumped before starting, don't know if it's related. Running pre-mix (no VRO) 89 octane, fresh gas, starts well, good compression, normal plug wear.

Thanks in advance for any suggestions, I appreciate it.

-Nick

 

[ScottGW]

Re: 1987 Evinrude 88hp surges about 4-500 rpm at high speed

Sounds like the fuel bulb is no good, it is essentially a check valve, and if it is failing it could cause flow problems.