1991 Johnson 40HP timing issue I think?

FAT

Recruit
Joined
Mar 16, 2009
Messages
2
I am working on a 1991 Johnson 2 cylinder 40HP engine.

Ok here?s the problem.

When I pull the top plug wire there is no change in the way it idles but when I pull the bottom wire it dies instantly.

Also I can only get it running by working the gas at the carbs.

Both cylinders has good compression.

It is getting spark to the plugs top and bottom.

I have replaced the plugs and wires and the coil.

I am just playing it by ear trying to figure out what is going on before I take it to the shop to have them fix it for 80.00 an hour.

Any help would be greatly appreciated

Thanks,

FAT
 

FAT

Recruit
Joined
Mar 16, 2009
Messages
2
Re: 1991 Johnson 40HP timing issue I think?

I just had the carbs gone through.

So it has new plugs/wires/new coil and fresh rebuilt carbs.

When I pull the top plug after running it is wet and black and the bottom plug is clean and dry.

Thanks
 

JB

Honorary Moderator Emeritus
Joined
Mar 25, 2001
Messages
45,907
Re: 1991 Johnson 40HP timing issue I think?

Sheesh! I sure wish folks would find out what is wrong before they start replacing parts. Too oftan they not only don't fix the problem but they introduce new problems. :(

Your top cylinder is not making power. What happens if you spray some fuel mix into the top carb while it is idling?

Have you examined the reeds for the top? What about gaskets?

What numbers did you get on a compression test?

What is meant by "working the gas at the carbs"??
 

tashasdaddy

Honorary Moderator Emeritus
Joined
Nov 11, 2005
Messages
51,019
Re: 1991 Johnson 40HP timing issue I think?

good compression tells me nothing what is it. will the spark just 7/16 inch? playing by ear is no way to fix a motor, do you have a Johnson service manual? have you cleaned and rebuilt your carbs with kits? did you remove all the jets and clean them?? http://forums.iboats.com/showthread.php?t=244013
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,771
Re: 1991 Johnson 40HP timing issue I think?

If the top plug is wet the engine has no or weak spark or the carb work was incorrectly done and that cylinder is being flooded. The fact that you have to work the carbs to get it running says carb problem. Timing is not an issue since it doesn't affect just one cyliinder. Is the red knob on the primer solenoid set in the PRIME position. If so that alone will flood the engine.
 
Top