1972 Johnson 6hp only runs with cover off?

[tomhath]

You say you had to fix the recoil starter - that means the previous owner didn't maintain the motor properly and just yanked it to death trying to start it.

First thing is to check for a good strong spark on both cylinders. It could also be dropping one cylinder when it revs (stronger spark is more likely to arc through bad insulation); if the plug wires look old/cracked they should be replaced. Make sure the points are set correctly so the timing is right and the plugs are correct for the motor. Also clean the carburetor and make sure all the gaskets/packing is good.

 

[itsaboattime]

^^^What he said^^^
Try to run it in low light and look for arcing from the wires. When you put the cover on it gives it another place to ground to, possibly closer than the spot it was arcing to with the cover off. Path of least resistance.
Carb kit and new impeller.

 

[nwcove]

You say you had to fix the recoil starter - that means the previous owner didn't maintain the motor properly and just yanked it to death trying to start it.

First thing is to check for a good strong spark on both cylinders. It could also be dropping one cylinder when it revs (stronger spark is more likely to arc through bad insulation); if the plug wires look old/cracked they should be replaced. Make sure the points are set correctly so the timing is right and the plugs are correct for the motor. Also clean the carburetor and make sure all the gaskets/packing is good.

^^^What he said^^^
Try to run it in low light and look for arcing from the wires. When you put the cover on it gives it another place to ground to, possibly closer than the spot it was arcing to with the cover off. Path of least resistance.
Carb kit and new impeller.

i must be wrong...but it almost sounds as tho you guys are implying that the op should check to see if it has good spark before he goes and buys a set of coils ?

 

[Tim Frank]

i must be wrong...but it almost sounds as tho you guys are implying that the op should check to see if it has good spark before he goes and buys a set of coils ?

Only if they did not see the pics of the current pair....

 

[BigB9000]

Here you can see the air intake area on the lower cowling, make sure nothings blocking that.

And the coils should look more like this:

 

[raaaidvw]

thanks for the pics. still need to get some coils then get a better set up to run it. I will post back

 

[Greg O.]

I frequently run a fan to give the motor fresh air. They always run better on a boat then in a barrel.

 

[itsaboattime]

Only if they did not see the pics of the current pair....

Yup...didn't see the pics.

 

[raczekp1]

i had few of this 6 hp motors made to 1977 and i havent seen compresion more than 90 psi

 

[BigB9000]

i had few of this 6 hp motors made to 1977 and i havent seen compresion more than 90 psi

Nor have I.
90 sure.

The used powerhead sellers on ebay claim numbers of 125 and 135 though?

 

[raaaidvw]

ok finally got around to picking up some coils ,impeller and a tune up kit with new wires. put it together tonight but need to install it on the motor now. heres a couple pics of before and after. I notice the new coils look like they are in an ABS plastic as opposd to whatever the other ones were. also the mounting area is green on the old ones. do you think the coils were replaced before? the ends that connect to the points had an eyelet put on with what looks like your normal blue plastic crimp ons.

 

[F_R]

The coils in your picture look like the ordinary standard issue original equipment. Hint: Push the ground wires back on your new coils. The way you have them, they will rub on the flywheel hub, wearing them through.

 

[AlTn]

check that condenser wires won't touch as well...the oiler wick may need trimming as it can "jam" underneath the points arm to an extent that the rub block on the arm can't touch the points cam...just something to be watchful of

 

[raaaidvw]

ok got the motor running like a champ today. adjusted the lean/rich mixture and it seems to be working good. it idles real nice and doesn't stumble like before. the old coils just crumbled when I took them out. I also installed a 90 brass fitting onto the thermostat housing so I could run a pee hole out the bottom of the engine case so my son can make sure water is flowing through the motor. got a new impeller im going to install tomorrow for some piece of mind. I ran the motor in a 5 gallon pail and had a fan blowing behind me to push away the exhaust fumes. gonna take the flywheel off tomorrow and address those wires that you guys mentioned aswell. thanks again for all the help.