Howdy. I'm new to forum. My 800 has run fine for years. I had it out today and ran it harder than ever. Lots of hill climbing etc. when I shut it off for a water break it would not start correctly. The fuel pump sounded strange too. Normally when I turn the key on the pump has a crisp pressurizing sound. Today it sounded different. I could make it start but any throttle resulted in backfires and the engine would die. Let It sit for 30 minutes and it started and ran fine for an hour. When I shut it down it did the same thing. Waited 30 more minutes and just drove it home. I replaced the fuel filter a few months ago as part of routine servicing. The fuel pump definitely sounded different when it would not start. The radiator fan came on as usual and the coolant is good. It seems to be temp related or induced. I would normally suspect bad pump but it works when allowed to cool. This is my first Polaris so I would like some ideas from more seasoned owners. Has anyone seen this?

 

Could be a fuel pump problem or could be a sensor harness problem. Look at the "sticky" post in the expert section above this one on the 700 and 800 efi electrical problems. The thin harness wiring caused all sorts of problems. Would run good awhile,then run crappy. If you find any bare or soft small sensor wires,then this could be the problem. Several people have used the OTB harness and connector kit mentioned in that section.Only The Best If you have a fuel pressure gauge and adapter to fit the fuel rail you can check the pump pressure out. It should hold 39 psi with no drop.

 

Thanks for the help. I read the article on the wiring harness problem/solution. It sounds like a good place to start. My 800 has always taken a long time for the fan to come on. I think the radiator and engine get too hot before the fan switches on. I have not seen an overheat indicator light but it feels awfully hot. I wonder if the new harness could fix that too. Thanks again for the advice. I will post my findings.

 

Doubt if the harness will help the fan situation out,but you can follow the harness from the fuse block and relay harness and you'll find a circuit breaker taped to the harness. This breaker supplies power to the fan relay. If it starts to get weak or corroded,this could be a problem.It's either just a square metal breaker taped to the harness or will be enclosed in a pouch depending on the year model.

 

One other thing is if the fan motor is weak,beginning to go out it can take more amperage to kick on. You can pull the sensor wire on the left side of the engine.The fan should work when the key is turned on. Hook a dc ammeter to the orange/black and ground wire of the fan harness.If the fan takes more than 15 amps to kick on it may be close to time to replace the fan. Spal provides the fan motors.Spal Electric Fans - The Fan Man

 

Take a can of gas with you next time you ride. When it gets hot and dies, top off the tank with gas and see if it doesn't start right back up. The fresh gas will cool off the fuel pump and if it is a fuel pump problem, it should start up and run right away. The less gas you have in the tank, the hotter the fuel gets, and with an older pump the heat can cause it to lose pressure. That's why after it sits a while and cools off it will start back up and run until it gets too hot again. It's simple and worth a try before you start throwing money and parts at it.