Johnson 150 cutting out

[doublenickel]

Hello All,
I'm having a problem with a '96 Johnson 150 (J150EXED) that I'm hoping someone recognizes and can help with. Late this year it began totally cutting out at various speeds. At first it would literally die like you had switched off the ignition when idling out of the canal. Then it began going down to idle speed (not actually stalling) when running at mid or high RPM, but would then suddenly accelerate back up. Next it would die (once again like the ignition had been shut off) when up on plane, but will always (so far) re-start.
The other day it shook like I hit something right before it died, but once again started right up. It has also had a slightly erratic idle since this all started.
I have replaced the ignition switch, but no help. Also, the VRO was replaced last year.
It has not shown these symptoms (yet) when hot, only when cold, which seems to go opposite of what I would expect from a powerpack issue.
There are no alarms associated with this either.
Any help is greatly appreciated.
thx

 

[tashasdaddy]

Re: Johnson 150 cutting out

check all connections for corrosion. where are you? fresh or salt water?

 

[Chris1956]

Re: Johnson 150 cutting out

What is the condition of the primer bulb when it stalls or looses speed? Can you pump (several pumps) gas into the carbs? If so it is likely an air leak in the fuel line, dirty fuel filters or a malfunctioning antisiphon valve in the fuel tank pickup.

if not, you need to check the electrical connections, look for loose wires, mising insulation etc.

 

[doublenickel]

Re: Johnson 150 cutting out

thanks guys, a little more info: the boat is used exclusively in salt water, so I'll check for corrosion on electrical connections this weekend.
When this started I switched to a portable tank to try and start eliminating things, no change.
The bulb is pretty firm when this happens, but it can be pumped a few times if I really try. It is not collapsed or changed in any way appearance-wise that would indicate restriction either, and as I say there are no alarms at all either.

 

[Benny1963]

Re: Johnson 150 cutting out

check coil grounds and run with timeing light pointed at you and see when it running bad if each cyl is consistently strobeing on each wire

 

[prh3]

Re: Johnson 150 cutting out

I am new to the forum. I may have a suggestion for your problem. Last fall I was out for a run with my 97 150 and it started doing the same thing. It was like someone was turning the ignition on and off. Ended up being the shift switch which is located under the shift linkage at the motor. It drops out 3 cylinders whenever you shift. It was sticking in and out causing erratic power loss. Try disconnecting it and see if your problem goes away. My dealer told me that most people just leave them disconnected to save the 75.00 cost for the part.
prh3

 

[ezeke]

Re: Johnson 150 cutting out

I agree with prh3, the switch could easily cause all of those symptoms. All you have to do to disable the switch is to disconnect the black ground wire that runs to the engine block. Be careful though, shifting can be much more difficult without the switch.

 

[hydrasport18]

Re: Johnson 150 cutting out

I have a 94 150 that was doing the exact same thing. Ended up bding the shift switch also. Installed a new one and all is well.

 

[doublenickel]

Re: Johnson 150 cutting out

Thanks much guys,
It took a long time to post because the boat's been out of the water for the winter, but it appears that replacing the switch (sensor?) that was mentioned at the shift mechanism may have been the culprit. I have only run the boat twice, but no sign of the issue returning.

Thanks to all for the brain power.