04 Johnson 150 2 stroke idle problem

[parrott]

Idle problem:
Motor cranks fine cold and runs good through rpm range.
Cut motor off and after sitting for 20 to 30 minutes, restart motor and idles fine. Put in gear and motor cuts off. Restart and does the same thing. Advance throttle and run rpms up in neutral to 1300 to 1400 and motor stays running after putting in gear.
Any suggestions on what to look for? Mechanic did richen up the idle but it didn't do any good.

[thefermanator]

Sounds to me like a vapor lock issue. They normally show up on a hot re-start after they have had time for heat soak. I know I have experienced this problem with the new E-10 fuel in several cars I have worked on lately.

[mboy]

VERY VERY common problem with these engines. I had same issue on my 2003 175 Looper.

I did a DUNK decarb and it went away.

[debugger]

Yeah decarb and plugs. Maybe bump the idle a touch. I had a 02 150 that did it from day one. lean snort and die.. usually when you kicked it in reverse when your approaching the dock.. Always started right up cold but it would start stalling and idle low the first time you anchored up to fish the first spot and shut her down for a while. Mine had a cheesy all plastic throttle linkage without an idle stop screw. you bumped the idle by advancing the timing. The dealer made it better but it never did idle as good as I would have liked.. but ran perfectly otherwise. Bought it brand new and sold it a year later for an EFI.

[atlanticbeach]

It is likely a carb issue. When the motor is idling, it can have trash in the bowls and not stop up the jet until you advance the throttle and begin to drain the bowl to supply the cylinders. You might try draining the carbs to see if any piece of trash might come out before tackling a carb rebuild. It is a common occurrence but a rather easy fix. Take the air silencer off and the lower cowlings. Then remove the brass plug at the bottom of each carb and tilt the engine up and drain all the fuel from the bowls. You have to remove the lower cowlings to get to the carb on #6 cylinder as you cannot reach it with a screwdriver or ratchet. While the motor is up, get small screwdriver and remove the high speed jet from each carb and then spray some carb cleaner in each of the carbs through the high speed jet plug you just removed and hopefully any trash will come out of the bowls. I have done this in the past to try and escape a complete carb rebuild to remove any trash that can get in the bowls and stop up the jet once you give the engine the throttle.

Good luck. It might be a little messy but there is a good chance you will solve the problem. Decarb will do nothing for trash in the carbs and it is not electrical.

[dtmackey]

Google "lean sneeze Johnson" and you will find a wealth of information related to your issue.

D-

[parrott]

Thanks
Will try some of the suggestions.

[eggsuckindog]

You didn't mention the " Lean Sneeze" so carbs too lean is out - I wouldn't bother draining the bowls as it should plenty of fuel at that stage- I would maybe do a decarb and possibly just bump the idle up a 100 or so

you didn't mention the RPM its idling at

[atlanticbeach]

Parrott,

I did forget the one other thing that might well be the problem and it slipped my mind as it has been a few years since I worked on outboards. The shift interrupter switch is located on the bottom of the cable assembly and if that switch is bad, it will knock out one bank of cylinders once it is put in gear. This switch is designed to momentarily knock out a bank of cylinders to prevent gear damage when shifting from forward to neutral or reverse. If the switch has continuity when shifted into forward, then it is knocking out a bank of cylinders and that will cause the idle problem. It many times it the carb bowl with trash but this is easy to eliminate. Follow the wires from the switch and one will ground to the block and the other connects to a billet connector on the side of the engine. You can remove the billet connector and test for continuity with an ohm meter.