1972 Evinrude 65 HP bogs/misses at WOT

[edgexswitchback]

I'm hoping someone here is smarter than my outboard guy and me. He has been working on these since they were new and is stumped.

Symptoms: Will fire right up hot or cold. Will idle or run at low speeds all day. Try to go WOT and it will start to pick up but then slowly loses RPM's (but will never die). Can't get it to completely stall no matter how hard I try! Seems to be misfiring on a cylinder.

What's been done: New water pump. Good compression (120ish) on all 3. Fuel pump rebuilt. Good fuel lines. Checked for obstructions all the way from tank to carbs. Carbs are super clean. Floats set properly. New plugs and wires. New fuel in tank. No water or derbis. I did a siphon from the tank to the motor to make sure it wasn't pulling in air and to make sure it had good flow. Reeds look good (from what I can tell with the carbs removed). I don't know the resistance values for them but all 3 tested about the same.

Thanks in advance for any tips!!!

 

[edgexswitchback]

Somebody....Anybody?!?!?

 

[racerone]

When you throttle up look into the carburetors with a strong flashlight.------Compare fuel coming up the main jets.-----------Hook up a timing light one cylinder at a time and see how spark behaves when you throttle up.---Does spark jump an actual gap of 1/2" on all 3 leads after motor has warmed up ?------My compression tester would show 140 + on one of those motors.

 

[edgexswitchback]

Solved....sort of. It was drawing air in from the fuel line fitting at the tank. I could hear it pulling air in from there when I pumped the primer bulb (not sure why I didn't notice this before). Runs great now with my grandpa's fuel tank. Question is it possible to replace the tank fitting or do I need to get a new tank? It's not the hose but the tank.

 

[F_R]

Repair the tank outlet fitting (assuming you have an OEM tank). See the little pins that get pushed in when you connect the hose? One of those has a little brass washer around it. Behind that is a teensy o-ring. You need to replace the o-ring. You need to buy that o-ring, two more o-rings that are inside, and new core plugs that you will destroy when you remove them to get the pins out.

OR go ahead and buy a whole new fitting. That will help the economy with your spent $$