1974 Johnson 70HP

[Reeb]

I just recently bought a Galaxy 1974 15 ft with a Johnson 70HP engine. I took it out on the lake and moved the throttle to about 75% and it started to plain for about a min and then it started to sputter and then just die. Then it wouldn't crank for about 2 hrs. When it finally did start I turned around and tried to head back to the dock and in about a min it died again. Sounded like it wasn't getting enough gas. And once again it took a few hrs for it to crank. In the driveway with water hose connected up it cranks almost everytime. Could it be bad gas, spark plugs, idled to low for when it's in the water, fuel filter (didn't even see one on there), or can anyone think of something else? I appreciate any help. Thanks.

 

[Bifflefan]

Re: 1974 Johnson 70HP

could be all of those things.
When were the carbs overhauled last?
sounds like a good ture up would help a ton.

 

[Reeb]

Re: 1974 Johnson 70HP

I'm not sure when last time for carbs. The guy I bought it from hadn't had it out on the water in over a year. I'll try a tune up for it. Thanks for your help.

 

[clarksparky]

Re: 1974 Johnson 70HP

I just recently bought a Galaxy 1974 15 ft with a Johnson 70HP engine. I took it out on the lake and moved the throttle to about 75% and it started to plain for about a min and then it started to sputter and then just die. Then it wouldn't crank for about 2 hrs. When it finally did start I turned around and tried to head back to the dock and in about a min it died again. Sounded like it wasn't getting enough gas. And once again it took a few hrs for it to crank. In the driveway with water hose connected up it cranks almost everytime. Could it be bad gas, spark plugs, idled to low for when it's in the water, fuel filter (didn't even see one on there), or can anyone think of something else? I appreciate any help. Thanks.

well the thing is i had that problem and when you putt it on the ears there is no presure like when it is in the lake so it runs fine.you have an exhuast manifold leak and when it is in the lake with full water presure it doesnt exhuast through the prop it is exhausting through the hole or bad gasket within the engine case and getting sucked in back threw the carburaors .i had to take the whole power head off and jb weld the exhuast manifold file it down and replace the gasket . carburators dont run good when sucking in exhuast fumes instead of freash air. good luck hope i helped

 

[Daviet]

Re: 1974 Johnson 70HP

If it has old gas in it, the jets could be plugged.