Quad runs perfect when it's just short runs. Run it 4-5 miles up hill (fairly steep) and it pulls as it should. Coming back down using Engine Braking it begins to backfire after a mile or so then at the bottom if you stop it will stall. Once started and going again it will not tack above 3500-3800. Shut it down and an hour later fires right up and runs perfect.

It's not over heating. It needs some TLC before winter and would appreciate any suggestions It's a 2007 Sportsman 500 EFI with 1580 hours.

Side note. The seat and right side plastic on that quad is absolutely destroyed. It is parked in a shop every night. The upholstery went first followed by the plastic frame which is cracked really bad. The rear plastic on the right and side panel melted where the exhaust comes around.

Has Polaris had any recalls for this terrible engineering? I have a 96 Polaris and compared to the 07 it's perfect with 3000 hours. The seat is still in very good shape. Gona buy another quad next spring but Polaris is not looking good.

Appreciate any suggestions ...thanks.

 

Look at the tps connector and wiring along with the t-bap connector and wiring leading into the main wiring harness. Check for any obvious bare wires or soft feeling wires that have melted internally. Common problem on the efi machines. They may or may not throw codes and normally not a problem with the sensors them selves,just the cheap connectors and thin wires. Most common problem was the t-bap wiring and connector: back firing,no idle or erratic idle. Above an idle they would usually run ok.Better harness repairs kits are available than the cheap Polaris kits I had to work with.https://otbpowersports.com/products/ 2007 efi models had an exhaust kit and extra foil shielding under the rear fender area.The kit was not a mandatory upgrade,just for ones that had over heating problems that brought them in for this problem.The kit is probably nla by now,but you can check the 2008 model Sportsman 500 that did have the upgraded shielding that would work.http://www.partzilla.com/parts/searc...UST/parts.html and also the foil shielding under the rear fender area.Items#13 through 16.
http://www.partzilla.com/parts/searc...EAT/parts.html

 

Thanks for the reply.

Yeah kinda thinking it is an electrical problem. Hear a lot about those connections you mention. Seems like I saw a repair kit for like 3 connectors for around 100 bucks. Maybe just go that route to start. I'll check that link you posted for the parts.

As far as the plastic...its shot!! Needs to be replaced. I did put in some baffles to defer the heat as a quick fix couple years ago but it was to far gone. What is more frustrating is the broken seat. Because of the cracked plastic the seat has sagged down and broke the air box mounts and is shoving it down against the tyranny.

Again thanks for the input!