I have a 2000 Yamaha Kodiak that starts great every time. Once I'm driving it, it will go along and then sputter and die. It seems like some sort of fuel problem, but I can't narrow it down yet. I recently replaced the choke cable as it broke off where it enters the carb. I put a new o-ring gasket on the carb bowl and new jet needle (set identical to old one with clip position, etc.) in the carb.

I thought it might be a vacuum issue, so I put a brand new gas cap on it. No dice.

I have a new fuel petcock for it, but haven't put it in yet.

My brother in law is a mechanic and said it could be a bad crankshaft seal which would cause the engine to die when warm. He said this would be a costly fix if it is the problem.

The engine starts great when cold. It will run fine for a few hundred yards and then it dies. I can start it back up and run another short distance before it dies again.

How would I check the seal my brother in law is talking about?

Thanks in advance.

 

Your brother-in-law thinks you have a two stroke. Have you tried running with the petcock on prime? In fact take the pipe off and see if you get a good stream of fuel when on prime. Your problem could be electrical too, a hot plug, coil, CDI, regulator, stator or signal generator can break down.

 

Run it with out a gas cap on to eliminate a fuel venting problem.

 

Ok, thanks guys! My bro in law asked if it was a 2 stroke and I mistakenly told him yes. I'm a dumba$$, sorry. I just replaced the fuel petcock and it still dies after running for a bit. The old petcock looked fine - completely clean filters and no sign of anything being bad. The Kodiak still starts fine and runs, but bogs down and then dies after riding for a quarter mile, so it sure seems like a fuel problem. It turned over a few times and then started again after it died. I was able to pull it into my shop and let it idle, but then it died again after a couple minutes. I put a brand new gas cap on it a couple weeks ago thinking it was a venting problem after talking to my bro in law.

What else would cause a venting problem if not the gas cap? The only thing I can think of with my limited knowledge is the plastic piece the jet needle sits in within the carb....maybe I'm way off.

The CDI was replaced last year when I thought it was faulty, but it ended up being a bad battery.

How do I check the coil, regulator, or stator?

I appreciate the help.

 

Ok, I let the Kodiak idle in my shop. It idled fine for 10 minutes with the cap off and another 10 minutes with the cap on. What does that mean?

 

Think I have it solved......it was a real PITA, but I replaced the ignition coil. It seems to be running much better and not dying. And a correction to my post above which I don't know how to edit, I replaced the starter solenoid earlier, not the CDI. Good to go!