1995 Johnson 70hp problems

[boydog40]

my 70 is giving my mechanic fits, while running at any speed it will act like someone reached and pulled the wire off of one of the plugs and then put it back on continuously
what has been done
1) all 3 carbs rebuilt/new carbs kits etc
2) all 3 coils replaced
3) all 3 plug wires replaced
4) all 3 plugs replaced
5) new powerpack
and no change with all the above done
any ideas/suggestions/etc???

 

[boydog40]

Re: 1995 Johnson 70hp problems

oh yeah, all fuel lines large and small have been replaced as well

 

[boobie]

Re: 1995 Johnson 70hp problems

Put a timing lite on each cyl when running, turn it around and look in to it. If you see any black spots when the prob occurs that means you have an ignition prob. If the ignition is okay, go back and look into the fuel system.

 

[boydog40]

Re: 1995 Johnson 70hp problems

can this be done on the hose? or only in the water?
also what do you mean by "turn it around and look into it"? look into the timing light from the "light" end? after problem occurs? and there should be black spots in the light?
if this is correct I will try tomorrow and revert back

 

[patrick4266]

Re: 1995 Johnson 70hp problems

I'm assuming ,after doing all that, you did a link and sync?

 

[boydog40]

Re: 1995 Johnson 70hp problems

keep in mind all the above was done by a outboard mechanic and not me so i am not sure if he did that or not, I can ask him and see and revert back

 

[boobie]

Re: 1995 Johnson 70hp problems

On the timing lite test you use your ears and eyes. When the mtr jerks look for a black spot in the timing lite. This means you have an ignition miss and lack of spark to fire the timing lite. And it's not after the prob occurs, it's when.

 

[boydog40]

Re: 1995 Johnson 70hp problems

in the pitch dark last night i cranked her up looking for electrical leaks, all i could find were all 3 plugs leaking where the porcelain meets the metal, with more rpms the blue leak became brighter, hopefully this will explain the high speed miss - will replace all 3 plugs and advise
thanks for all the advice

 

[boydog40]

Re: 1995 Johnson 70hp problems

new plugs no change at all

 

[clanton]

Re: 1995 Johnson 70hp problems

Metal core sparkplug wire used? Check the ground wire on the plate that the powerpack mounts on. Check the powerpack mounting bolts. Check all wires behind the powerpack mounting plate, for bare spots. Correct sparkplug and gap?

 

[boydog40]

Re: 1995 Johnson 70hp problems

well after several hundreds of dollars spent with same results each time (no change) the problem was finally located! first mechanic had rebuilt all 3 carbs when he did he put the wrong size high speed jet in the center carb (guess he was doing more than one carb job, grabbed the wrong jet) anyway $27.00 later, the correct jets and she is back to screaming down the lake like she is accustomed to!!
i wanted to share this in case it might help someone else in the future
thanks for all the help
merry christmas!