1977 140hp won't throttle up

[big dreamer racing]

I rebuilt the fuel pump, checked the spark, 3 cylinders (1,3,4) have spark @ 1/2 inch gap, cyl. 2 has no spark until tester gap is shortened like 1/4 inch so that tells me weak coil possibly? Next question it idles fine on muffs & at first in the water, then I idle out of dock give it throttle gradually upon 3/4 to full throttle she falls flat on her face & dies, starts back up ok, then same thing @ throttle. Eventually she's hard to start & will only idle with the start lever full on & activating the choke a moment at a time. At that time it won't idle in gear at all. Fuel lines aren't restricted.
Please help Memorial day is almost here.

 

[wildmaninal]

Re: 1977 140hp won't throttle up

I'll say, I had the same problem with my 78 85hp evinrude a while back. Thought I had good spark from a previous spark check, checked the spark again and was puzzled because it didn't show that good of spark like it did before. Thought I might of had coil problems, turned out that the coils are fine.

I couldn't get my motor to throttle up either while in gear. I rebuilt the carbs and linked and sync the motor and it runs like a top now.

What you can do is do a coils test, I believe there is a thread on this under the FAQ section of the Iboats Forum, you will need a meter.

You could also get the motor running and take that one plug wire loose that shows weak spark and see if that makes a drastic change in the engines performance. Or you could ground the spark plug against the head and spin the motor over and see what the spark is like then.

I'm leaning towards a fuel system problem. If you haven't cleaned and rebuilt the carbs in a while you may want to do that. I found out depending on what brand spark tester you have they are not that great, just my 2 cents.

You do have your vent open on your gas tank? Does the bulb pump up tight?

 

[big dreamer racing]

Re: 1977 140hp won't throttle up

Thanks for helping, the fuel vent is hooked & open. I bought this motor in March & I believe it sat for a while before that, it came from a wrecked boat (torn transom from hitting something) so who knows how it previously ran, I have had it over 40 mph the first time out, then it died and now here I am.

 

[wildmaninal]

Re: 1977 140hp won't throttle up

I hate to say this but unless you work a miracle tomorrow you might not get to run the motor on your boat this weekend, but if you have a trolling motor you could always troll along.

Do you have a manual for that motor? If you are handy with a wrench and have some mechanical exsperience then you might be able to pull it off. Your local marina should have the carb kits. You should take the carbs off and soak them over night then take and blow them out (each port/hole) with 120 psi coming from the air gun. The link and sync part can be a pain, especially if you don't have a manual, I know I've been there. To be honest I just installed a tach on my boat and will know soon if the boat is performing like it should finally. I was just assuming that it was performing good before.

 

[wildmaninal]

Re: 1977 140hp won't throttle up

Does the fuel bulb pump up tight/firm when pumping?

 

[big dreamer racing]

Re: 1977 140hp won't throttle up

Yes the bulb pumps up firm, I have a glass filter before it & it shows fuel in it.
I will check the link & sync & coil test tomorow , I figure I don't have to disassemble/pay for anything major for that. I have a pretty good manual.

 

[wildmaninal]

Re: 1977 140hp won't throttle up

I can't remember what the carb kits cost right off hand. I'll be darned if I can't find the link I wanted to post, the link will show diagrams, part numbers and prices.

Check those areas (that you mentioned) out and let us know what you come up with

 

[Timmstng67]

Re: 1977 140hp won't throttle up

Hi
I am new to this sight must say it is a great place for information. I have the same motor a 1977, 140 johnson...I had the same problem last year. Clean your carbs and make sure low and high speed jets are clean. make sure you don't mix up the jets, I did one at a time to insure not to mix them up. And make sure floats are adjusted properly and you should be good. I Did it in about an hour or so.....if you are mechanically inclined it should be a fairly simple job.......Also make sure you do a link and sync after install of the carbs.

 

[jtexas]

Re: 1977 140hp won't throttle up

That motor can idle just fine on 3 cylinders and sound happy to do it, then fall flat when you put a load on her. Bogging like you described is a symptom of clogged carbs, but you know you have inadequate spark on #2, that can be the cause. Swap the coil with another cylinder, if the problem follows, replace it.

Get the spark issue fixed and take her out for a test run if you like. Were it mine, I'd go ahead & do the carbs now - after sitting awhile they're likely need it, and she always just sounds happier with a fresh carb rebuild.

 

[big dreamer racing]

Re: 1977 140hp won't throttle up

I tore one carb apart today it was fairly clean, boy these carbs are simple aren't they, well when I mentally compare them to an automotive carb.
Now I'll just order the rebuild kits. Sierra 18-7046 kit shows a needle & seat but how about a part number for a float? I haven't found one yet.

 

[Timmstng67]

Re: 1977 140hp won't throttle up

Hey
Try this link It should get you every thing you need http://12.2.215.22/pub/default.asp?SessionId=cfb504daff5f4e179dfa81bed0e3aa69&Lang=EN&brands=EJ

 

[Timmstng67]

Re: 1977 140hp won't throttle up

Ps here are the people I use good prices just click on the Evinrude Johnson logo and it will take you to the BRP parts guide
http://www.bestboatparts.com/store/Evinrude/

 

[jtexas]

Re: 1977 140hp won't throttle up

yup, remarkably simple. If the floats aren't saturated (and they rarely are), no need to replace 'em.