2003 Johnson 25HP stalling under load

[ronnieb09]

Hey guys, I recently purchased an 03 25hp 2 stroke which ran fine until yesterday. Saturday we took it out and ran it for nearly 2 hrs throughout the throttle range, and had plenty of power. Yesterday I took it out and it stalls under load. The only thing that changed was I added 2 gallons of fuel and 5oz of Evinrude oil to the tank. The engine idles fine and will run in gear until you increase throttle and it will stall and die after a minute or so. I initially thought it wasn't getting fuel, but the tank and lines are all new. The tank is venting properly and the bulb has fuel when it dies.

THe cylinders have 120psi warm and I've got spark, though the plugs do not look clean(covered in black oil). I've cleaned them a few times and reinstalled, with no change in operation. The engine will start back up fine, but has no power under load and continues to stall. I've got a Johnson service manual on the way, any suggestions? Any way to check timing?

 

[jbjennings]

Re: 2003 Johnson 25HP stalling under load

Just from what you described, I would say you have a sticky float needle caused by a little varnish or whatever that broke loose when you started running fresh gas through it because it sat idle for a long time. I'd take the carb bowl off, clean the needle and seat and look for any signs of trash or gunk in the carb. bowl that would indicate a possible trashy needle seat.
It obviously sounds like you're losing fuel supply.
One last thing-----those crappy walmart fuel lines have primer bulbs that have the worst check valves in the history of outboarding. If I recall, I've had that happen more than once on my '99 johnson 30hp. If you have a different fuel line, try it. I've also had a split hose in the tank that allowed the motor to suck air. I'd try taking the end of the fuel line off and just dipping it in the tank and seeing how it ran or better yet, take out the connector from the tank and check to see that crappy plastic pickup tube in the tank isn't split. Now that I think about it, I'm fairly confident it's either the check valve in the fuel line, or a split pickup tube allowing it to suck air. If not, then sticky float needle. Let us know what you find.
Just my opinion,
JBJ

 

[tashasdaddy]

Re: 2003 Johnson 25HP stalling under load

i vote dirty carb, high speed jet and or float needle valve. http://forums.iboats.com/showthread.php?t=244013

 

[ronnieb09]

Re: 2003 Johnson 25HP stalling under load

The fuel tank and lines are from walmart(Attwood Marine). I checked the pickup in the tank, and it appears fine. I did consider the check valve last night. I think I may order an OEM bulb and check valve to eliminate it. I will also order a carb kit and go through the cleaning procedures.

Is it normal for the plugs to be covered in black oil? I would think they should be cleaner.

 

[ronnieb09]

Re: 2003 Johnson 25HP stalling under load

I went and picked up an OEM Johnson fuel line/bulb kit and carb kit. So I go to put the new fuel line/bulb on and realize the old one is on reverse. I must have reverse direction when I removed the tank to add fuel and never thought to check. I'll chock this one up to inexperience and me being an idiot.

I'll go check the engine under load tomorrow, keep you guys updated.

 

[Mas]

Re: 2003 Johnson 25HP stalling under load

That'll do it!

MAS

 

[snail pace]

Re: 2003 Johnson 25HP stalling under load

I had the same problem last week with mine, i foolowed the advice i recived on here which was clean the carbs. Even though they looked clean when i but the air hoes on them the amount of gunk that came out was shocking. The engine runs sweet now. Also found my throtal arm was not pulling on enough too.

CHECK & CLEAN THE CARBS PRETTY EASY TOO.

Good Luck

 

[ronnieb09]

Re: 2003 Johnson 25HP stalling under load

I tested the engine last week under load, and the reversed bulb check valve is what was causing my problem. I went ahead and bought a carb kit for it so I plan to clean it anyway.

 

[Rick.]

Re: 2003 Johnson 25HP stalling under load

Good thing it didn't start. It might have made the motor run backwards. Human error. We can't live with out it. Rick.