1968 Johnson 6HP outboard runs great for 4 or 5 mins then dies

[matt laitres]

I was warned about this when I bought the boat. the gas tank and line all looks in good condition, my 1st thought was the fuel pump because the line going from the pump to the carb was clear and I could see air bubbles in it. I bought the new version of the fuel pump they are selling for it and new lines ( still clear to the carb) and there is no bubbles or hiccups in the fuel now so I feel pretty confident that is not the issue, but after I put all the new stuff on it and started up in 2 pulls and idled beautifully for 5 mins then out of nowhere dies? anyone have any suggestions? please and thank you!

 

[oldboat1]

Fun five minutes, though, right? (sorry)

could be losing spark. If coils are cracked, they will let you down (and may be doing that). I would pull the flywheel and check -- use a harmonic balance puller.

 

[ondarvr]

Check to see if it has spark when it dies.

How soon can you restart it?

​Try squeezing the bulb before it dies and see if that helps.

​Does pulling the choke on as it dies make a difference?

​Some of these motors have a cork gasket near the high speed jet, if it breaks down the small pieces float around and occasionally plug the jets.

 

[matt laitres]

damn I was really wishing i was not going to get a answer that had anything to do with spark or anything that required messing with flywheels/ points and so on because I have nothing to pull the flywheel with as I have found in the past with other small outboards iv owned. and to answer you, ondarvr it wont start for at least 10 mins ( after that i got frustrated and walked away). I will try to squeeze bulb and mess with choke while its dying tomorrow and after it does ill check spark, ill have to youtube the hell out of the carb issue speak of to learn how to take that all apart. thank you tho guys

 

[oldboat1]

Ondarvr's question hints at overheating. When you have to wait, is the top of the head too hot to touch?

 

[matt laitres]

its warm but i wouldn't say to hot to touch. I also had the initial thought of overheating but it seems to be peeing pretty good, I suppose if I have time tomorrow tho I will drop lower unit and make sure impeller is still good. is it possible for it to overheat if its spitting water out tho?

 

[mla2ofus]

I had the same problem oldboat described with my '54 Rude 15HP. Coil's insulation was cracked, ordered new ones, installed them and the problem went away.
Mike

 

[tomhath]

Sounds like either the coils or the condensors are failing.

Removing the flywheel is usually easy. A steering wheel puller doesn't cost much at any auto parts store. Take the spark plugs out and stuff as much rope as you can into one cylinder to stop the crankshaft from turning, then loosen the nut so it's just level with the top of the shaft. Put the puller on, doesn't have to be real tight - just enough to have some some pressure. With one hand, take a thin wooden stick like a paint stirrer and gently pry up on the flywheel until you seen it and the crankshaft lift a fraction of an inch (don't use a screwdriver or prybar or you might damage the flywheel) . Then whack the top of the puller with a heavy hammer, the flywheel will pop loose.