johnson 60hp surging at wot

[fishfeatures]

1990 60hp j60elesm

took it out for a spin yesterday and at wot it surged very badly. Large fluctations in revs (i've it set to do 5600 WOT) from 5600 to 4800. Once eased off into 3/4 throttle it'd cruise all day but go to WOT and it'll start surging. I swopped out the fuel line and bulb last week as I suspected an air leak as it was surging even at cruising, but prob not solved.

Carbs have been rebuilt with kits not too long ago , could the pump be my issue???

 

[jbjennings]

Re: johnson 60hp surging at wot

THe way you describe it, it sounds like a fuel supply problem. I would pull the fuel lines off the carbs and get a helper to tun it over with the plugs grounded and see how much flow you're getting from the fuel pump, or, even easier---just have a helper pump the primer bulb while your'e running wide open. If it fixes it, you've got a fuel pump problem/clogged filters/ split in the pickup line inside the tank (seen it before)/air leak in the intake or somewhere else. I hope you post back when you find the culprit.
Good luck,
JBJennings

 

[Chris1956]

Re: johnson 60hp surging at wot

Does the primer bulb collapse? Can you pump it to keep the motor running at WOT?

Check for restriction in the fuel line. The antisiphon valve is a prime suspect. Any filters are as well.

 

[fishfeatures]

Re: johnson 60hp surging at wot

I did pump the bulb when out there but it made no difference and it wasn't collapsed. I don't have an antisiphon valve and filter was changed last week along with the bulb.
I'll re check everything again starting with the tank ,all the way to the carbs and see what i find.