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Dominick
Dominick, Marine Mechanic
Category: Boat
Satisfied Customers: 1009
Experience:  25 Years Experience as Mechanic, 20 Yrs Boat Yard Owner/Mechanic, Factory Certified
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I have a 1982 70hp evinrude out board motor, it starts good,

Customer Question

I have a 1982 70hp evinrude out board motor, it starts good, but I have to put around slow for three or four min before I can power up to full throttle, it goes great to get out to start trolling Itroll with my elec motor for two or three houres, then try to leave it starts well but I cnnot go full throttle for three or four min, before I can kick it up to full throttle. I have had it to three machanics,none can fix it. one says its the carbs cleaned and checked, did not work, one said it was the fuel pump and gas, rebuilt fuel pump, changed to no alcohol gas, that didn;t work,one said it was the timing that it needed to be retarted . that didn't work. this has been going on for eight months. please help Ron Sitzlar.
Submitted: 1 year ago.
Category: Boat
Expert:  Tan replied 1 year ago.

Hi Ron. My name is Tan.

Have you checked that you have spark on all 3 cylinders when you first start the motor?

Customer: replied 1 year ago.
no but it starts well runs great after warming up for around three min.
Expert:  Tan replied 1 year ago.

The engione needs fuel, compression and spark to run correctly. We can eliminate the fuel system as they have been gone through. We can eliminate the compression as the engine runs good once it does run correctly.

Leaving spark as the only thing that hasn't been checked or eliminated as the cause of the issue.

The spark must jump a 7/16" gap on a spark gap tester on all cylinders. This is the test we need to perform.

It is hard to tell if you have a misfire on a 2 stroke motor and it will run on 2 cylinders. It won't have any power on 2 cylinders till the 3rd cylinder kicks in. Which could be a spark issue.

Does this make sense?