Category Archives: ATV Repair and Maintenance

Starts & idles fine but won’t accelarate

I’m looking for any assistance in diagnosing this issue because I really don’t have the cash right now to take it in. I have a 99 Polaris Sportsman 500 that was running fine then after sitting for a month or so started having this issue.

The ATV will start relatively easily and appear to idle fine but upon attempted acceleration it bogs down and stalls. I can get it to move forward or reverse at a crawl if I shift it into low and feather the throttle just right but if I give it just a bit too much throttle, the engine stalls.

Here’s what I’ve done so far to try to remedy the situation:
* New plug
* Drain fuel tank and refill with premium (with some Seafoam)
* Bought a carb kit and rebuilt the carb and just to make sure – removed the carb a second time and checked and cleaned it. The carb kit came with all new jets, springs, gaskets, etc..
* Checked the fuel flow from after the fuel filter and it appears to be running sufficiently.
* The battery is strong.

I did call a mechanic in town who works on ATVs and he seemed pretty confident that changing out the fuel would resolve the issue… but it didn’t.

Any suggestions on what to check next would be greatly… greatly appreciated.