I am hoping someone out their can help me out. I have recently purchased a '99 500 Scrambler HO....rode all winter without a problem. Now that the heat has arrived, it is stalling when the quad gets hot. Seems like it is starving for fuel after riding for 10-15 minutes....today I pulled the tank, fuel filters, vent lines, air filter, carb etc and cleaned and checked everything I thought might be causing the problem. It worked better, but it still stalled on me. I blew air into the tank vent line and it seems to help, but it will not run consistent.....could it be fuel pump, coil???

Met a couple guys on the trail that suggested I post to this site. Anyone who has had any experieince with this or thoughts on how to fix.....looking for help.

 

Try doing a plug check to see if you are running lean or not. I would think if it ran good this passed winter, you would be running rich, since the weather is warmer. Is the quad stock?

 

Quad is stock.....so far...I checked and replaced the plug this weekend......it was running light brown.

 

try replacing your airfilter.

 

Howdy,

Does it cough, spit and backfire before it stalls? Does it idle fine, but as soon as you try to accellerate it will start missing? If so, I know what the problem is. If not, I don't have a clue.

Mike

 

Its vapor locking, my 700 will do it sometimes, wrap the fuel lines with heat tape, This helped mine.

 

Heh Trailblazer,
The bike does cough, spit, backfire and then die.......give it throttle and it is starving for fuel. As far as the idle it depends, sometimes it will, other times not.....

 

Your problem is probably not fuel related. Believe me, I replaced a whole ton of Sh*t on my bike before I actaully found the problem. With 95% confidence I would say that your problem is a worn exhaust lobe on your camshaft. The 500cc Polaris engines are famous for it.

I replaced mine with a used one (along with a used Exhaust Rocker) that I bought off ebay for $120.00. It took me three hours to fix it myself (And I am not very mechanically inclined) with the aid of a shop manual.

I should be good for another 7 years!!

 

i think you are right too... i was reading down the posts and i was just about ready to post that problem, and i read yours

Younger, that could be your problem due to the heat causing the exhaust valve to not open all the way when your engine gets warm

 

Finally got a chance to get back to you....thanks for your help, but after several tear downs and inspection of hoses, fuel pumps, carb etc, I pulled the fuel valve out of the gas tank......you wouldn't believe the amount of dirt on the intake filters for both the main and reserve lines.

I cleaned them up and it no longer stalls........now if I can just get it to stop backfiring when I let off the throttle.