1976 johnson 70hp bogs

[josh5058]

This boat ran fine when I bought it. Ran for the first day out no ploblem.
Then it starts to bog around 2000 rpm. Read about the problem and changed fuel pump, cleaned the carbs. The problem was fixed for around two more runs. Then the bogging comes back. Im calling it the bogging monster now. Second fix was the #1 coil. Fixed problem for a little while. Then its back. Rectifier wires were shot, so i replaced them. Same Thing. Nother problem, changed Thermostat and control valves. Same thing. Replaced wiring harness. Same thing. Replaced Power pack. same problem. It would run fine for a while then start to bog. Now it runs for about a half hour then starts to bog. Could this be a heat problem? If I idle it aroun for a little while it will run good for a little while. Like its playing games with me. I put good gas in it and I take it fishing when it wants to go. I'm just sick of changing parts and trying this and that, but I really cant afford to take it to a mechanic. Can anyone tell me something that might help me get rid of the bogging monster?
Would replacing the impeller help? Im pretty sure the previous owner replaced it before I bought it.

Thanks,

Josh
EDIT: email addy not allowed for your protection, use the PM system. TD

 

[james williams]

Re: 1976 johnson 70hp bogs

It might be getting trash in the carb.I would reclean the carbs and put a good filter just in front of the carbs.It might be getting trash out of the tank..james

 

[josh5058]

Re: 1976 johnson 70hp bogs

I Replaced the impeller and housing, and I Pulled all three carbs and cleaned them. Then we ran the boat and the same thing happened. So we figured one of the cylinders wasnt firing, and we were right. The center cylinder wasnt firing. so we switched coils 2&3 and it ran fine. The next day, with the coils still switched the bogging came back. Then someone told me that the stator could be causing the problem. If anyone can tell me if this could be right I would appreciate it.

 

[tashasdaddy]

Re: 1976 johnson 70hp bogs

this may help you : http://www.boatpartstore.com/page30.asp

 

[josh5058]

Re: 1976 johnson 70hp bogs

Ok, so the guy that told me to replace the stator should get some kind of prize. Just put the new one on yesterday. Ran the boat for about an hour today and it ran fine. Tommarow Im gonna fill her up and run her for as long as I can. Hopefully Ive fixed the problem.

 

[jay_merrill]

Re: 1976 johnson 70hp bogs

I kind of surprised that the stator seems to be the problem - usually if the stator is bad, you'll have problems in all three ignition "paths." From what I have read and have experienced personally, what you are describing is more often a powerpack and/or timer base problem.

Since you have replaced both the powerpack and the stator, as well as one of the coils, I suggest replacing the timer base too. I think I would replace the other two coils also. You may as well since everything else is new, plus you won't have to fool with the motor for a long time.

 

[tashasdaddy]

Re: 1976 johnson 70hp bogs

Done, Jay. TD