1976 70 HP Evinrude ( Need some answers)

[stone_holder]

I have a 1976 70 hp evinrude that will run perfect for the first 5-10 minutes and then if i shut it completely off and then try to restart it idles a little rough and then when i put it in gear it dies if i try to accelerate.If i just leave it at idle speed in gear it will stay running but the moment i give it throttle it will die. I tried changing sparks plugs and got the same results. The compression is fine(130 lbs) in each cylinder. New fuel pump was installed and it's definitely getting fuel to the carbs. My timing at idle speed in gear is 4 degrees BTDC. The spec's call for 3-5 degree's ATDC for the idle but i can't get it there because it will die. I have cleaned the carbs and today i installed new needles and seats but have not tried it yet.Any answers would be greatly appreiciated. Thanks.

 

[Firewood]

Re: 1976 70 HP Evinrude ( Need some answers)

How do the plugs look? Are they all firing?<br />Also is the thermostat o.k? Make sure its getting up to temperature.Make sure the float is set and it closes the main jet, maybe gas is overflowing from the carb and flooding it causing a rough restart.I thought the old motors drained down once they shut off??

 

[stone_holder]

Re: 1976 70 HP Evinrude ( Need some answers)

The plugs are slightly wet and all three seem to fire good when grounded to the side of engine block.I replaced the thermostat when i rebuilt the powerhead this spring.I have not checked the operating temp yet. but the hot horn works and it has never came on so it's not overheating. I don't think the carbs drain down after shutoff, the carb bowls are still full of fuel when i diassemble the carbs. Any other suggestion? Anyone?

 

[walt]

Re: 1976 70 HP Evinrude ( Need some answers)

I had a similar problem with an '83 50 hp Evinrude. Tried most of the things you have. Finally, I was told that the wiring harness on that model was known to go bad and cause those symptoms. I changed it out and it was still running great when I sold it last fall.