1982 70hp Evinrude RPM dropoff

[cassfam7]

This is attached to a light, 16 ft. center consol. Motor starts great and idles. When you take it to higher RPM it runs OK for a short time and then drops to lower RPM and sputters. If you run it at 3/4 throttle it hesitates every 30 seconds or so and then drops off. when you throttle all the way to idle and then push back it will again hit the higher RPM for a short time. The problem seemed to get worse as it warmed up. Have a new prop, but that seems to be working great. I have owned the mortor since October, could it be sprak plug related? I have not done a lot of work yet. I wanted to get it in the water and see how well it ran. I guess now is the time for the work. Thanks for the help. I am A novice! Dave

 

[vano6990]

Re: 1982 70hp Evinrude RPM dropoff

What RPMs are you getting to? Are you using new gas? Check the fuel filter? If you press your gas bulb while it hesitates does it improve? I have had my 115 e-rude for a year now and would suggest doing a compression test to your cylinders first. They should all be within 10% of each other. Good Then check spark. Should be blue and snappy. Good then look into rebuilding the carbs. If the fuel filter/pump are good. Get a good owners/repair manual. Will help you the most. marineengine. om is where I found mine.

 

[krmelton]

Re: 1982 70hp Evinrude RPM dropoff

I have a 76 115 and it pull the same stunt today. I put on a new fuel pump before this last run, the old on was just leaking, and a new piece of fuel line to the pump. I popped the top and saw the fuel line was a little long and "kinked" at one spot. I worked the kink out and she opened up. Maybe it will help.

 

[cassfam7]

Re: 1982 70hp Evinrude RPM dropoff

Ok, thanks for all the advice. I started simple. When looking to replace the fuel filter I noticed the screen was dirty. I cleaned and replaced it, and am waiting for the tide to rise so I can launch the boat. Do I need to purchase a new fuel filter or can I just clean the screen. No obviouse kinks. <br /><br />I did notice that one of the spark posts, oposite the plug, was not as clean as the other two. It was the top one. Is that an problem to be solved? Thanks, Dave

 

[jtexas]

Re: 1982 70hp Evinrude RPM dropoff

If gas doesn't come out of the fuel filter when you pump the primer bulb, don't rebuild it until you see whether cleaning the filter solved your problem. Probably did. Spark plugs really should look the same - wouldn't hurt to get new ones if you don't know how old those are. Champion QL77JC4 at .030. Did you happen to notice whether the telltale was peeing good? After that, follow flathead hunter's advice.<br /><br />That's a great motor - you'll get it sorted out.

 

[cassfam7]

Re: 1982 70hp Evinrude RPM dropoff

Got it out yesterday, seemed to do better then started same thing. The telltale is peeing well. I will get to plugs ASAP. It seems to correct itself at times and then losses power again. I will keep trying.

 

[cassfam7]

Re: 1982 70hp Evinrude RPM dropoff

I have obtained the service manual. Wow, I needed that! I have noticed that most pictures of the motors have a cover over the carbs. My motor has no cover, the carbs are exposed. How important is that. The post on the top coil is in bad shape, corrosion, What is this a sign of?