Thread: 150 johnson

Try pumping up your bulb before taking off.

My motor was doing that a few months ago and I ended up replacing primer bulb. Check valve in pump was leaking by letting gas run back in tank. Like Terry said next time out, before you crank motor pump up bulb then start it and see what happens.

ive replaced primer bulb, plugs,wires

This is a common problem with this engine and I am assuming this is a carb engine. I have had three things cause this on my engine with the most common thing being that the timing roller arm has slipped. In simple terms the timing advance and carb plates have to start moving at the same time and the timing roller adjusts this. You can go to bassboatcentral and in the Johnson/Evinrude forum their is a sticky at the top that shows how the roller should look but the timing arm has to move when the carb plates move. You also have a rubber clear tube that goes on the arm that advances the carb plates that will get dry and fall off. Make sure it is still on the roller. If this is verified you may need to decarb the engine. If you have not ever decarbed the engine start by putting a can of Sea foam in your gas for several tanks before doing a full decarb. I use Seafoam in every other tank to prevent carbon buildup. The last thing is to back out your idle fuel screws on each carb a half a turn out . All of these have caused my engine to do this in the 12 years I have owned it. Good luck.