1979 70hp Johnson stalling

[marcusknight]

I have a 1979 70hp Johnson and I am curious if this is supposed to happen. My engine runs and operates well but more often than not when I start it (especially when its warm), it will run for a few seconds and then quit. In order to avoid this, I have to use the neutral throttle lever to give it extra gas. Once I shift it into gear, it seems fine. Is this normal for a two cycle engine or should I have the carbs and fuel system cleaned?

 

[fireman57]

Re: 1979 70hp Johnson stalling

Sounds like you might have your idle set too low. It is best to set it on the water because it needs the back pressure of the water to get it where you want it. Should be around 900rpms or so at idle.
If you don't know when the last time the carbs were cleaned you will probably want to do that. Could be a low speed jet clogged. EAsy to do yourself.

 

[TrueNorthist]

Re: 1979 70hp Johnson stalling

Not to step on the toe of Indiana :wink: but sometimes altitude will make the engine stall, or even slight differences in fuel etc. I like to keep my motor idling as low as possible for trolling and have to make adjustments all the time for different conditions. I figure that is why the manufactures typically made adjusting the mix/speed so easy. If you do not have a tachometer I would strongly suggest you get one and do as Fireman suggests but be ready to make small adjustments. It is normal.

 

[BonairII]

Re: 1979 70hp Johnson stalling

Are you choking the motor when you try to start the motor(when it's already warmed up)?

My motor(see sig) starts like a dream cold, but sometimes it hard-starts when I am ready to move to another fishing hole...normally it's because I hit the choke when I go to start it(out of habit)....and it doesn't need choke.

Another cause of the hard-starts can/could be that you're losing prime....and need to pump the fuel ball again.

Just throwing some ideas out there....

 

[marcusknight]

Re: 1979 70hp Johnson stalling

I havent been choking it when starting warm. It actually starts up "instantly" when warm. It just often dies after about ten seconds unless I put it into gear and / or give it some throttle.

 

[BonairII]

Re: 1979 70hp Johnson stalling

Set your idle speed(rpm)when your boat is in gear. Normally it's about 1000-1100 when on muffs.