I'm working on a 2006 Sportsman 500 HO that won't run except for idle with the choke pulled completely out. I wasn't riding the quad at the time it messed up but was told it started sputtering like it was running out of gas so fuel was put in it and ever since it hasn't been able to run over idle and only with choke on. The gas put in it was fresh and was used in several other ATVs without problem so I don't think the gas is bad or contaminated. I pulled the carb off and the jets and all orifices were cleaned out which nothing was found plugged or dirty looking inside it. I pulled the top end diaphragm out and inspected and it was pliable and in good shape, it seemed to make a good seal around the top of the carb. It acts just like a carb problem when the jets are plugged but I can't find anything or any vacuum leaks. I don't know much about the fuel pump system they use on these quads but could a weak fuel pump make it act this way or do these systems need priming if ran out of fuel?

 

did you check the fuel filter?

 

Pull the fuel line from the carb and crank the engine over. Should be a steady or pulsating stream of fuel if the fuel pump is ok. Look at this on the BST40 carb on cleaning/adjusting float level and see if it can help.The BST-40 Bible | Adventure Rider If the carb and fuel pump checks out ok it may not be fuel related but electrical as the ecm module on these machine can do some crazy things at times."IF" you're one of the many still running around that hasn't had the recall performed,it's still free as it was a safety recall.Polaris Industries Expands Recall of ATVs Due to Fire Hazard | CPSC.gov Plus even if you have had a replacement they can fail also. If you don't have a manual here's one that can help narrow down the problem you're having.2006 Polaris Sportsman 500 Service Manual PDF Download

 

I just got the ECM replaced under that recall a few weeks ago and it ran good for a couple weeks before starting this. I'll do the fuel pump check you mentioned and look over the BST-40 write up. If it were the ECM would Polaris warranty that since it was just done by a dealer the first of last month? I'm pretty certain it's fuel\air related the way it's acting though.

 

Nope,one replacement is all that's allowed. If the new one fails the next one one come out of your pocket. Hopefully it is just a carb/fuel related problem.

 

Fuel filter has no restriction, I blew air through it and it seemed like there wasn't even a filter element in it as there was such lack of backpressure when I blew through it.


I pulled the fuel line off the carb and cranked the motor over and got a steady flow from the fuel pump but probably a stream less than an 1/8" diameter. I then used a priming bulb with hose, like found on an outboard boat motor, and supplied fuel to the carb with this along with some pressure and I got the engine to rev up once using this method so I though for sure at that point it was the fuel pump but I tried the same method again and I couldn't get repeatable results so I'm still thinking a carb problem.


Does the flow I observed from the fuel line sound normal or too little? I think it would be enough to keep the carb bowl supplied but if it needs any pressure at all I don't think it's outputting enough to do that.


Any other suggestions for troubleshooting this problem are appreciated.


I think next step will be to pull the carb again and check the float needle setting according to the BST-40 Bible link above.

 

Sounds like fuel flow is enough as once the engine cranks and runs good vacuum pressure is increased on the pump to keep the bowl full.If you pull a carb always replace the needle and seat. Cheaper to just get a kit rather than an oem needle and seat.http://www.ebay.com/itm/CARB-REBUILD-REPAIR-KIT-POLARIS-SPORTSMAN-500-H-O-4WD-2003-2004-2005-03-04-05-/230385051279?hash=item35a404e68f&vxp=mtr Plus on this one be sure to set the float level correctly.

 

Just thought I'd follow up on this post. I pulled the carb a second time for inspection and had a rebuild kit this time to install and noticed lots of clear jelly looking stuff in the carb bowl. I cleaned that out and changed out the rebuild parts, reassembled and still the same thing, it would only idle with choke fully on and wouldn't rev up. I then suspected the gas because of all that jelly looking stuff in the carb only 3 weeks after I had pulled it and cleaned it before. I drained the "full" tank of fuel, close to 5 gallons and had probably 3/4 of a gallon of something in there other than gasoline. I put the fuel in some glass wine jugs and milk jugs and could see a separation of liquid in there and the heavier liquid on the bottom was heavy enough to float sandy looking grit on top of it yet underneath the gasoline. Well the tank was drained the best I could get it, put fresh fuel in it and it's running like a champ now. I don't know if it's diesel, kerosene or what but I pulled some of the heavier liquid off the bottom of one of the jugs, put in a steel can and it burned so it wasn't water.


This ATV was used at a big concert festival for moving band equipment with a little trailer and several operators and I know they had diesel fuel on site along with gasoline to refuel generators but I'm not sure if that's what it is, doesn't really smell like diesel.


Anyway contaminated fuel was the problem with this one.


Thanks for your shared knowledge Old Polaris Tech, you've helped me out a few times before just reading through some other peoples' threads. That carb rebuild kit you linked for me was quality and at a good price.

 

Water.. Had enough problems with it on the pwcs. Water is heavier than gas and will settle at the bottom of a clear container.

 

I hot a 2018 Polaris sportsman got it in water not it won't start only back end sunk. Drained air box and belt box turned it up and let water drain out what else should I try