70 hp johnson missing

[jspitzer]

hey guys i'm still working on this problem with my 70 hp johnson. I had a stator and power pak put in it last year, motor starts and idles fine. It will run down the river great for about a half hour or so then start missing, it cuts in and out like i'm turning the key on and off. I put a new ignition switch in it,and have rebuilt the carbs.I'm just kind of stuck on what to try next.kind of thinking the coils but sure would like some help.

 

[duke3]

Re: 70 hp johnson missing

Well well well............hmmmmmmmmmm.<br />After down the river for about half hour and the problem starts, what happens if you stop the motor and start it again ? Is the problem then gone or ????? <br />If problem not gone, then next time stop the motor and disconect the black/yellow wirer there are comming from the power pack. When you do that, you will remove the the "kill" to the motor. Start it again, and see if the problem is gone. If so, the problem is in the kill system. If not gone, connect the black/yellow wirer again. Then make a control on your gaz-tank, that there is no wacoum in it.

 

[Goodoleboy]

Re: 70 hp johnson missing

I would suspect you have a coil thats droping out when heated up.<br /><br />You can test the coils for heat failure, while runing on the muffs.<br /><br />Take a hair dryer and heat each coil and see if you can cause it to drop a cylinder.<br /><br />It could also be that you have a partialy blocked vent on the gas tank. Mite wana try a spare tank for a couple days.<br /><br />Idd do the coil check first tho.<br /><br />If problem goes away, then replace vent valve on tank.<br /><br />Good luck!

 

[jgough]

Re: 70 hp johnson missing

I have the exact problem with my '71 125hp V4...After reading about jspitzer's 70hp, i will try replacing the coil and report back!<br /><br />Thanks

 

[Walker]

Re: 70 hp johnson missing

Check the coils, clean the coil grounds and clean every ground wire connection that you can find.

 

[jspitzer]

Re: 70 hp johnson missing

checked all the ground already and they seem to be fine. I have two gas tanks in the boat and it does it with both tanks. I'll try the coils and let you all know, Thanks for your input....