1985 Johnson 70hp lemon??

[mike francois]

Idles fine untill put in gear. Then kills and if accelerated to high speed it also kills. If carefully<br />primed while speeding up I can get it to top speed and runs fine. New carb kits and floats<br />(this did not help at all).Sometimes motor will preform fine then put into reverse and accelerate<br />and motor dies out.Compression 112,115,112

 

[Franki]

Re: 1985 Johnson 70hp lemon??

check u'r fuel pump and lines...sounds like either the pump is clagged or you have an air leak in your lines somewhere...<br />Its not a lemmon <br /><br />rgds<br /><br />Frank

 

[12Footer]

Re: 1985 Johnson 70hp lemon??

No, you haven't wasted much money on it with the carb kits. It is the first place i would've probably sent you.<br />Next, the fuel pump should be rebuilt.Since you have fairly good compression, we know the pump has plenty to werk with, provided, it is werking.<br />Put a good, inline filter in the fuel line, and rebuild the fuel pump.That SHOULD get you going.

 

[Yepblaze]

Re: 1985 Johnson 70hp lemon??

Usually a carb overhaul consists of more than installing kit(s) If that's all that happened while it (they) were off, I'd say take em apart and get those jets and passageways clean.

 

[fireman 757]

Re: 1985 Johnson 70hp lemon??

I agree with Yepblaze. Your high speed jet has some crap in it. This has to be perfectly clean or you end up with no high end and sometimes no idle.

 

[mike francois]

Re: 1985 Johnson 70hp lemon??

The carbs were soaked and cleaned completely, fuel pump has 21/2 lbs. at carbs.

 

[mike francois]

Re: 1985 Johnson 70hp lemon??

Also I sat in back and squeasd the bulb while running ( no help)Also has good filter. Anybody know what factory compression is? Thaks a mil

 

[mike francois]

Re: 1985 Johnson 70hp lemon??

 

[Dhadley]

Re: 1985 Johnson 70hp lemon??

What grade fuel? What spark plugs (and please be specific -- dont say "the right ones") What oil and ratio? What brand kits? What were the carbs soaked in?<br /><br />I think the guys are correct about the carbs needing some additional attention if the sync and link is all correct.<br /><br />Good luck!

 

[mike francois]

Re: 1985 Johnson 70hp lemon??

Soaked carbs in carb cleaner and sprayed all fuel galleys,air ways and removed jets and inspected them. Also used 130 lp. air pressure on all parts.Installed Sierra (A Morse Control co. Litchrield Ill.) carb kits and floats.(set as instructed in kit instructions). New Champion Marine plugs QL77JC4. Using unleaded regular 87 octane. Took it in to a OMC dealer and had link synk checked,and timing. Mechanic test run in water and will try changing Idle jets today. Mechanic said that 85-87 motor had this prblem and there was bulitins put out but he had little luck with repairing them. Eliminated VRO mix OMC oil 50:1. Please help!!!

 

[Dhadley]

Re: 1985 Johnson 70hp lemon??

Yes indeed there were many jet changes on those motors. It has to do with the fuel changes from the 80's to today. I think you are on the right track. Everything looks good except I don't have much faith in those kits. <br /><br />When it's at idle in neurtal and you just put it in forward (no throttle) does it just fade out and slowly die? Or does it die as soon as it goes in gear?<br /><br />Let us know!

 

[mike francois]

Re: 1985 Johnson 70hp lemon??

When Idiing and put in gear it just dies. OMC mechanic took off head,bad news engine has scared cylinder, will need bored and pistons for sure. Hope this model is worth time and money. Like the man said "boats" break out anouther thousand smackers.Thanks a million for all the help.