1988 Johnson NEED HELP ASAP

[fishook76]

I have a 1988 Johnson 60hp that isn't running right. I'm looking for help in diagnosing what is happening. Here is what has been happening and what I have done. Took it out from winter and during the first run it had about 1/2 power when the throttle was full/wide open. I put new plugs in, made sure it has fresh gas, cleaned all carbs and put new gaskets from the carbs to the airbox. When I went back out, for 2-3 minutes it ran fine, then started cutting in and out from 1/2 to full throttle (in and out sporadically) . Over the next 10 minutes or so it gradually worsened until I only had 1/2 throttle/power again.

Since things changed, I tend to think its in the carbs but I have cleaned the and they look great. Any ideas on testing them and or the electrical components? I've heard I could be "dropping a cylinder" meaning one cylinder is not firing.... Please help, my inlaws are coming tomorrow and I would like to have it fixed. Thank you!

 

[skyboy2410]

Re: 1988 Johnson NEED HELP ASAP

The same thing happened to me on my 70 HP Johnson It had dropped the #2 cylinder. I replaced the powerpack and it helped some. Then had all three carb's rebuilt and it was fine. Turns out tyhe high speed jets were not opening.

 

[Joe Reeves]

Re: 1988 Johnson NEED HELP ASAP

If you did not manually clean the high speed jets that are located horizontally in the bottom center portion of the float chamber... way in back of the drain plug, do so as cleaning with solvent just doesn't do a proper job on cleaning those jets.

Check the compression... what are the readings?

With the plugs removed, check to see that the spark on all cylinders will jump a 7/16" gap with a strong blue lightning like flame... a real SNAP!

Hopefully your using Champion QL77JC4 spark plugs, gaped at either .030 or .040 . Let us know what you find.

 

[glenn property of pam]

Re: 1988 Johnson NEED HELP ASAP

theres minor things you can do rule out a few problems like

does the fuel bulb get stiff when engine is not running
when running and playing up if you pump fuel bulb does it get better
what do the plugs look like are any clean or extra wet
does the timing linkage move with the throttle (not running so you can see whats moving)

If its not the above then you really need to borrow or buy a compression tester and a spark tester

what's the compression numbers
do you have a good 7/16 spark (use tester) on all cylinders
warm motor up then test spark again to see if one drops when hot

sry posted at same time as joe so just a repeat of what he said

 

[fishook76]

Re: 1988 Johnson NEED HELP ASAP

When I cleaned the carbs I did remove the jets in the bottom of the bowls. I could shoot carb cleaner and air freely through all of them. I can also see through them and all looks good. I will check compression and spark next. What should the compression be?

 

[fishook76]

Re: 1988 Johnson NEED HELP ASAP

well, its been a while but I've been messing with this motor ever since. here is what I have done and where Im at with it. I had a buddy who is a marine mechanic come and take a look at things. He found, by using a test light and cross referencing with other coils, that my top cylinder coil was bad. we switched with other coils and confirmed that whatever cylinder had that coil on would not run. so, I bought a coil and replaced it.

1st time out, it ran perfect for the 1/2 hour that I was testing it.
2nd time out, when I first stated it the motor was running on 2 or maybe even 1 cylinder for about 2 minutes, then it came out if it and ran perfect for the rest of the time.
3rd time out, it was only running on 1 or 2 cylinders fro the start and I could not get it to come out of it so after about 10 minutes I pulled it out of the water.

After using good coils to test cylinders that were not running, I found the whatever coil I used, I could not get cylinder one to fire. I did many test cross referencing parts. Ie, if cylinder was firing fine and 2's coil works, I put it on cylinder 1 and it didn't work. putting it all back together, using plug wire from cylinder 2 on cylinder 1 and it didn't work. I didn't the same with new plugs. every time I cross referenced parts, I couldn't get cylinder 1 to fire. I thought it was the power pack. so I put in a new power pack. nothing changed. still, I can not get cylinder one to fire. This is with, a new plug (Champion QL77JC4 ), new plug wire, new coil and new power pack.....any suggestions??? I have not checked length of spark and compression yet, I will today. but , tell me if Im wrong, with all those new parts on there, shouldn't that all be fine? Thank you!!