1984 Evinrude 40hp surging

[Outlaw8289]

Idles fine. Ok all the way up to about 1/4 throttle. Revs up and down after that. Will stop if I keep pumping the primer bulb.
I have put a new fuel pump after this happened. Did not change anything. I’ve cleaned the carbs multiple times and also pulled the lead ball and metal cap off to clean the high speed jets and blew it out with air.

New spark plugs with blue string spark
Sanded down all exposed electrical connectors to eliminate the posssibility for a bad ground
blew out fuel lines
opened fuel tank just in case it wasn’t venting
checked float level
motor has good 150 psi on each cylinder
Pulled fuel lines off and pump is pumping
fuel pump has new gasket to power head also

It all points to a fuel problem, but I’ve ran out of ideas. The only thing I could think of to try at this point is check the timing.

 

[fireman57]

You did your homework and it does sound like a fuel problem. Try using a different fuel line and primer bulb. Maybe the anit siphon valve is bad. It won't be timing unless your flywheel key is sheared. You might want to check that.

 

[kbait]

Agree w/fireman^.. but add tank. If a neighbor/friend has a J/E outboard, borrow their tank/hose and test it. If it still surges without constantly squeezing primer bulb, it’s still a fuel delivery issue. I believe your carb has a primer instead of a choke..that would be the next place to look..
Good luck!

 

[Outlaw8289]

Changed primer bulb. Found a fuel line possibly kinked but didn’t know if it was at the time, Runs good now. Thanks for the help.