Old Evenrude 35hp Hard to Start, Dies.

[ORnewBoater]

I am new to 2 stroke/boat motors. I have an older Evenrude BigTwin 35hp outboard pull start motor. Spins freely without spark plugs. I cleaned out the carb. Not certain if the upper adjuster is in correct. I was not able to remove it when I cleaned the carb. The motor is very hard to get started and once it starts it is harder to keep it running. I have been able to keep it running for 30-40 seconds and it sounds fairly good. It always ends with a pop (backfire). I've worn out the pull cord not to mention my back trying. Any tips or tricks?

 

[bktheking]

Re: Old Evenrude 35hp Hard to Start, Dies.

Verify you have spark on both cylinders and good compression. If you have both i'd point the finger at a fuel delivery problem.

 

[Mas]

Re: Old Evenrude 35hp Hard to Start, Dies.

Is this a pressure tank or fuel pump model? You may have an air leak in the lines??

Sounds like a fuel delivery issue. Was the carb float set level?

Mas

 

[ORnewBoater]

Re: Old Evenrude 35hp Hard to Start, Dies.

It has good compression and spark. The fuel delivery is pressurized tank. That very well could be the issue. I have two tanks and I recall one leaks air when I disconnect the quick release and I was having better luck with the tank that I know to be good. Also when it does start, after it dies I can squeeze the inline primer ball nearly 2 full times and hear the float bowl fill.
Does the motor pump air to pressurize the tank?
Any tips for troubleshooting/repairing the fuel delivery system?
Thanks for the replies.

 

[Mas]

Re: Old Evenrude 35hp Hard to Start, Dies.

If the tank has an in-line primer bulb...it not a pressure tank. A pressure tank has two lines to the tank. One is from a nipple behind the carb on the crankcase and the other to the carb. Crankcase pressure from the piston's down stroke pressurizes the tank to feed fuel to the carb. The tank should have a little button or a knob like the old coleman camp stoves to initially pressurize the tank. Motors with pressure tanks do not have fuel pumps. OMC around 1959 went to a fuel pump and did away with the pressure tanks.

Mas

 

[ORnewBoater]

Re: Old Evenrude 35hp Hard to Start, Dies.

Got it running. It is a pressure tank system. One of the previous owners installed an inline primer. Once I used the tank pump, I had better luck. Also the float was sticking and it would flood easily. Got all that sorted out and went for a fun trip up the river and back. Now I have a whole new problem. Motor runs great but it's popping out of gear. There was a crack in the mid section I welded and seems to be holding well but the gear problem persists. I opened the bottom and inspected the gears/dogs. There is some wear and rounding so I am looking for an economical solution to repair or replace the dog/forward gear.

 

[F_R]

Re: Old Evenrude 35hp Hard to Start, Dies.

Oh-oh, economical solution, you want? So does everybody else. There ain't any. Unless you find somebody that will give you the parts. Somebody might give you a whole motor.