1976 35hp Evinrude cranks up and dies out

[joelmash]

I am having trouble with my 35 hp Evinrude that was giving to me. I have replaced the water pump, thermostat, rebuilt the carb and fuel pump, replaced the points. It will start in full throttle and then dies when I throttle it Back. i am going to pull the carb and clean it again. I am getting a little frustrated with it. not sure what else to do. Please help

 

[IslandExplorer]

I am having trouble with my 35 hp Evinrude that was giving to me. I have replaced the water pump, thermostat, rebuilt the carb and fuel pump, replaced the points. It will start in full throttle and then dies when I throttle it Back. i am going to pull the carb and clean it again. I am getting a little frustrated with it. not sure what else to do. Please help

I'm no expert but that sounds like maybe dirty reed valves to me. Maybe some dirt got in when working on it? With carb off might want to try blasting the reeds with carb cleaner, ether, or some other thing that dissolves varnish/gunk. Was it running normally anytime recently? Do you have compression check numbers? Had an engine that would only run high throttle (and barely) before and it was the rings all gummed up and sticking. Soaked cylinders in some atf and seafoam and got compression back up and idle back.

 

[racerone]

With throttle handle in the idle position is the throttle plate closed ?

 

[joelmash]

Compression on both cylinders was 120 psi. No I do not know the last time it actually ran right. It was given to me. It looked clean an so far I haven’t found any major issue. I rebuilt the fuel pump and carb. I installed a new water pump , thermostat, plugs, points , coils. Has no tiller handle. Has remote cables. I am about ready to pull the intake off and see if I find anything.

 

[racerone]

Is the throttle plate closed in idle position ?

 

[joelmash]

Yes

 

[racerone]

Did you clean the high speed jet found inside the float bowl....That little item has been missed numerous times by folks in the past.

 

[joelmash]

I clean it and also the three little holes in the top of the carb. I have clean the carb twice cleaned all the little holes with a snail piece of wire and blew compressed air through it.

 

[IslandExplorer]

I clean it and also the three little holes in the top of the carb. I have clean the carb twice cleaned all the little holes with a snail piece of wire and blew compressed air through it.

A few more ideas:
If fuel pump just rebuilt may be worth checking it for flow, I like to put a clear fuel filter on right after pump to "see" it working consistently at various rpm ranges. If a check valve in diaphragm pump is stuck or not sealing well it may only pump at higher speeds. This shouldn't cause it to stall immediately at low throttle though bc fuel should still be in carb bowl, but if it is pumping weak/bowl low whole time it could. Try pumping primer bulb to make sure carb bowl is full and see if it stalls just as fast at low rpm. Usually pumps have 3 hoses, IN, OUT, and IMPULSE (from crankcase). Double check those too perhaps. May be a sticky check valve on impulse line barb on block (had that once), little carb cleaner usually frees it up. I have a habit of buying 100 packs of stainless steel hose clamps and religiously replacing all the old hoses and connections for peace of mind and reliability.

 

[joelmash]

I am going to do the clear fuel line today. I actually have a new fuel on it now. My fuel pump only has two lines. For vacuum it attaches right to the engine bypass cover which has a hole in the back middle for vacuum. There is a vacuum hose that runs from the bypass cover to the front of the intake manifold

 

[racerone]

The fuel pump runs with a PRESSURE pulse.----The other line is part of the bleed / oil recirculation system.

 

[joelmash]

Ok so I thought I would take the fuel pump out of the equation. I hook a clear fuel to a bottle of fuel with an air vent. It still cranked up when throttled up ran 10 -15 seconds and died out. Did that three times. No air bubbles in the fuel. I think I am at the point of checking the intake and Reed values

 

[racerone]

Maybe there is a leak in one of the 2 crankcases.----Not developing enough PRESSURE to drive the pump.----Reed valves might be the issue.

 

[airshot]

Did you repla e ALL the gaskets O rings, diaphrams, needles, seats and everything? Rebuild kit??

 

[joelmash]

On the carb and fuel pump yes. Which wasn’t much