1981 70hp Evinrude idles well but wont run at high speed

[dmadey]

I've got an '81 E70ELCIH outboard on my 1981 MFG Gypsy and started having some trouble with it last season. When going along at full speed, it would occasionally 'bog down' such that the boat would slow to a fast idle. This started happening more and more frequently until that was all it would do. Pumping the fuel bulb did not make a difference and the gastank vent would be open. I've done some work on it to try to repair this. I've rebuilt the fuel pump, replaced the powerpack, replaced and checked all plugs (good sparks), and tested the compression on all 3 cylinders to be about 110 psi. I've verified that all pistons are firing. I thought I had fixed it!<br /><br />Today, I took 'er out for the first time this season. After getting through the no-wake zone, I gave it gas and she ran beautifully at full speed for about 30 seconds...then she bogged down just like before. I putted around for a while but she wouldnt go faster than a 'fast idle'. On the water, I again verified that all cylinders were firing and pumped the bulb for the heck of it.<br /><br />Is it the carb? Hopefully this will sound familiar to somebody. Thanks a lot!

 

[Walker]

Re: 1981 70hp Evinrude idles well but wont run at high speed

Sounds like carbs to me. Tear them down and give them a good cleaning. And I mean good. All orifices, passageways, and jets must be sparkling clean.

 

[dmadey]

Re: 1981 70hp Evinrude idles well but wont run at high speed

Thanks very much, Walker. <br /><br />A related question for you.... in the past even when the engine ran pretty well at high speeds, it would always stall if you tried to accelerate too quickly, for example if you tried to pull up a skier. Do you think this might be another symptom of the carb problem?<br /><br />I bought 3 carb rebuild kits this morning. I've got a Seloc manual and a Clymers manual with rough diagrams of the carb. Does anybody know of a good online diagram of this carb?<br /><br />Thanks!

 

[fireman57]

Re: 1981 70hp Evinrude idles well but wont run at high speed

See if I can save Walker some time. Yep on the carb and try BRPevinrude or ishopmarine for diagrams.

 

[dmadey]

Re: 1981 70hp Evinrude idles well but wont run at high speed

PS: this is my first time rebuilding a carb. Any words of wisdom? I'm pretty sure these carbs havent been rebuilt for at least 10 yrs. I got some Berkbile 2x2 Gum Cutter Carb Cleaner from the man at the marina to use also. What's the best thing 'tool' to clean the carb with, e.g. toothpick? toothbrush? scotchbrite pad? clean rag?<br /><br />Thanks again!

 

[northvanwatertaxi]

Re: 1981 70hp Evinrude idles well but wont run at high speed

I brought my carb to the dealer, he charged 1\2 hour and it came back like new, sounds like your float's are emptying out, check filter, air leaks in fuel line and your bulb.

 

[dmadey]

Re: 1981 70hp Evinrude idles well but wont run at high speed

Thanks, Rob. But if this were the case, wouldnt the problem have improved when I pumped the bulb? Pumping more gas in had no effect.

 

[northvanwatertaxi]

Re: 1981 70hp Evinrude idles well but wont run at high speed

on my 82 johnson there was a filter before the carb, lot's of dirt in the tank, the slow speed needle gasket was disintegrating, and letting little bits clog the jet and the needle valve clip was loose, float was out of adjustment, the dealer had to drill something out and plug the hole. it would die at high speed too. <br />I installed a clear filter too so I can see the fuel

 

[dmadey]

Re: 1981 70hp Evinrude idles well but wont run at high speed

That's good info. Thanks, Rob.

 

[fireman57]

Re: 1981 70hp Evinrude idles well but wont run at high speed

Pumping your primer bulb only forces fuel into your carbs it doesn't make it go to the engine for firing. This is the way to check for a bad fuel pump. If you have crud in your carbs the low and high speed jets will be restricted very easily and lead to fuel starvation. Worse case is you have one carb that is not getting fuel to the cylinder and that means that you have no lubrication to that cylinder and you get to rebuild the powerhead or turn it into an anchor, or put it on ebay saying that it ran the last time you had it out. Rebuilding the carbs is pretty easy. Just take your time and use carb cleaner and blow out all the jets. When you get your carb kits replace the parts that apply to your carb as the kits have parts for different engines in them. If you checked the sites I gave you there are shop diagrams on there.

 

[dmadey]

Re: 1981 70hp Evinrude idles well but wont run at high speed

Thanks all! I rebuilt the carbs. That was pretty easy. The hard part is remembering how the choke linkage attached. Currently, my choke solenoid will pull the choke butterflies open but I cant figure out what spring (or mechanism) is supposed to close the choke butterflies after the choke solenoid switches off. Any suggestions?<br /><br />Also, based on strong advise by many on this forum, I just bought an OMC manual for this engine (E70ELCI). Hopefully this will help me across the board. I have been using Clymers and Seloc which have been OK for general info but dont have details you need.

 

[dmadey]

Re: 1981 70hp Evinrude idles well but wont run at high speed

Engines running great now!

 

[tina beat]

Re: 1981 70hp Evinrude idles well but wont run at high speed

i have the same problem with my motor but mine will bog out whin i put it in gear

 

[Toddo1]

Re: 1981 70hp Evinrude idles well but wont run at high speed

I have a 1981 J70ELCIM and I had the exact same symptom of it running fine then bogging badly. Turns out it was the Timer Base going bad and the number 1 cyl was sometimes not firing.

The only way I pinpointed it was the Timer Base finally gave out on the number 1 cyl completely.