62 18hp Evinrude cutting out

[zed2500]

About a week ago I bought a 1962 Evinrude. I only paid $150 for the motor and it is in stellar shape. It has brand new coils, points, condensors, plugs and wires. When I tested the motor it ran great from idle to wot. However this weekend I took it out with the family (of course) and it started and idled easy, however once I started to accelerate it acted like it was starving of fuel, eventually it would cough a little and then run fine for a few seconds and then bogg down again. If I ran it at 3/4 throttle it seemed to run a little better, but still not great. I adjusted the high speed jet screw but this had little to no effect on the performance. The only think that is different since the first operation and the second operation is I put a different prop on it (9x10 instead of 9.25x11) and I mixed fresh fuel for it. I did mix my fuel at 50:1. After reading several posts on the forum, I realize now that I need to mix it at 24:1.

Could either of these explain the difference in performance? Thanks in advance for any advice. you guys always seem to point me in the right direction!!!

Thanks,
Shawn

 

[bktheking]

Re: 62 18hp Evinrude cutting out

Carb ever been serviced?

 

[zed2500]

Re: 62 18hp Evinrude cutting out

The carb was rebuilt about a year ago according to the last owner. I have ordered a rebuild kit from my local dealer. Would running some seafoam through it help in the mean time??

 

[Daviet]

Re: 62 18hp Evinrude cutting out

Sea Foam will not unplug jets, it is great to keep your system clean, but if you have a plugged jet you need to over haul carb.

 

[zed2500]

Re: 62 18hp Evinrude cutting out

Well I fired the motor today in a test barrel and I think I found part of the problem. While the motor was running I pulled each plug boot off. When I pulled the bottom boot off, there was now change in performance. When I pulled the spark plug it appeared fouled. I dried and cleaned the plug, re-installed it and at first I couldn't notice a difference, but after about 10 sec. it sounded a little smoother. When I put it in gear and opened the throttle, it no doubt had more power.

My biggest concern now, is what would cause the plug to foul???

 

[Daviet]

Re: 62 18hp Evinrude cutting out

Oil/fuel ratio, weak spark, low compression, bad plug, plug gapped wrong, fuel mixture to rich.

 

[bktheking]

Re: 62 18hp Evinrude cutting out

That all depends on what it looked like, could be running rich or lean, a carb cleaning is in order before anything else.

 

[zed2500]

Re: 62 18hp Evinrude cutting out

The Plug was very wet and appeared to be covered in mixed fuel. All I did was just dry it off with a paper towel, and then blew it off with compressed air. It seemed to run better once I did this, but I won't know until I put it in the water tomorrow. I will hopefully have a carb rebuild kit by the end of the week, but Archery season starts on Saturday, so I don't know how fast I will get to the carb...

 

[kbait]

Re: 62 18hp Evinrude cutting out

I'd pull the carb and clean-blow out all passages, and if the float, and float valve are good, put it together with the float adjusted to be parallel w/carb body when inverted, add an o-ring (#47 from hdwr store, I think) to each of the needle packings. I leave the old ones in, unless they come right out. Turn high speed out to 3/4 turn from seated, and low speed 1.5 and start from there..

I'd probably first get (or make) a spark tester to be sure of bright blue 3/8" lightning. Especially on the 'offending' cylinder.. Good luck!

There's a link (or 20) on how to make a cheap spark tester if you search this site..

 

[zed2500]

Re: 62 18hp Evinrude cutting out

Well I took the motor out again today and I think the problem was the high speed jet was way to rich (It was open over 2.5 turns). I viewed TashDaddy's carb adjustment page and seated the high speed jet gently and then opened it nearly one turn. This seemed to really smooth out the engine and no plug fouling!! I also put brand new plugs in and mixed some fresh gas. I am still going to do a compression check and rebuild the carburetor once my supplies arrive.

On a side not the original prop that came with this motor when I bought it was a 9.25 x 11. I put a 9 x 10 on it and while it runs fine, I would appreciate a little more top end. Would switching back make a siginficant difference??

 

[kbait]

Re: 62 18hp Evinrude cutting out

You won't get more speed from the original prop. The smaller diameter, lower pitched prop should run about 250-300 rpms higher at WOT, and if you're not over-revving the motor with that, it'll actually be a bit faster, and troll slower (I really like that part). It's always nice to match your normally loaded boat with a prop that will match the engines max rpm. Search this post and you'll find many theories on how to measure RPM, properly load your boat, adjusting the tilt, shimming the boat transom to get your motor a bit higher to create less drag, and more rpm+more speed.. etc. I was amazed that I could plane my 14' wide deep alumacraft (max hp rated 25) with a '75 15hp and 2 good sized adults w/fishing gear and beer (just barely planed). I went to an 9x8 prop and shimmed it up 1 3/8", and she goes 17mph all loaded, and 22 w/me and fuel. And it'll troll slower than I'd ever need. If you try shimming (which made a world of difference), MAKE SURE you're pumping water at plane. (If I look at the cavitation plate at full throttle, it's just barely underwater). Good luck!

 

[zed2500]

Re: 62 18hp Evinrude cutting out

Thanks, Kbait. I have a 14' aluminum Larson, this motor definitely gets it on a plane nicely. I haven't tried using the gps to get a speed reading yet, but that will be next. With just me in the boat I expect it will go around 20mph +/-. Thanks again for the advice, and I will try looking into figuring out the proper rpm range for the motor and prop!! I love this forum, always someone who knows more, or at least has had similar problems.