Hello,
I have a 2002 Sportsman 500 that recently started overheating (temp. light came on and radiator fluid was coming out of overflow and fan was not running). I also started experiencing another issue prior to overheating (not sure if they are related) that I cannot start my quad unless I use the pull start. I tried jumping the battery with no luck.

So this is what I know so far:
I am having a battery/starting issue and quad only starts and runs with pull start. Lights and instruments do work.
Fan works. I bypassed it and it started running with no problem.
Radiator fins and screen are clean of dirt.

Does anyone have suggestions on where to start? Could my 2 issues be related? Should I consider the thermostat, radiator cap, temperature sensor, water pump, battery? Any help or suggestions is greatly appreciated!!!

Thanks,
Matt

 

I've seen 2 of them that did that same thing this year, both had bad head gaskets

 

the starter not working could be a loose wire, bad starter relay, the switch itself, bad ground, etc. Try jumping the terminals on the starter relay and see if it cranks, if so, you can eliminate the starter and ground.

 

First thing always load test the battery and check connections as the fan as well as everything else has to have a good 12 volts to operate. Same as the starter has to have. If the battery load tests ok,then you can try 12 volts directly to the fan motor and see if it is ok. If it is,then the most common problem on fans not kicking in/overheating is the thermal sensor at the bottom of the radiator shorting out. It's what triggers the fan. Item #21 in the parts break down. Dirt Cheap Yamaha, Honda & Polaris OEM Parts & Accessories – Cycle Parts Warehouse Plus make sure there are no air pockets in the cooling system. Just open the radiator cap and run until warm to purge any trapped air.
Same thing on the battery again if it has a shorted out cell in trying to electric start. Usually will recoil start with a dead or low battery,but not electric start. Plus seems like the 500 is the only one that also has problems if the pick up coil gets out of adjustment or weak. Just check the ohms on the White and White/Red pick up wires leading into the cdi module. Should be a round 97 ohms resistance + or minus 20%. If the pick up ohms out ok,could be like what this member found out was his problem.no spark to plug when using electric starter - Page 3 - ATVConnection.com ATV Enthusiast Community

 

If it is the thermal senor you can get one from a auto parts store. They use the same one as a 84-88 Nissan Maxima or a 86-89 Nissan Stanza.
I,m currently using a Blue Streak TS-127. Napa and Wells also makes them.

I had the over heat problem once and it turned out to be a air lock in the system.
You know this if the ATV over heats yet the bottom rad hose is cool and soft yet the top rad hose is hard and hot.
Both hoses should be hard and hot when circulating properly.

Not sure about the battery being needed for the fan.
When I bought my 2001 the battery was dead as a door nail yet I just pull started the ATV for 3 weeks and it ran great before replacing the battery to get my electric start back.

 

OK I was able to use a meter to find out a few things. The battery is at 12 volts so that doesn't seem to be the issue with starting. The starter is only at 7 volts. I ordered a new starter and solenoid so I will replace them this weekend. The fan operated fine when bypassed so I know that is okay. I also ordered a new thermal sensor and will replace that this weekend as well. I will keep you posted. Thanks for all of the suggestions!

 

What does the battery show under a load when trying to crank?? Should be no less than 9.5- 10 volts under load for 30 seconds. If it shows less then you still can have a dead cell. 12 volts really doesn't mean the battery is up to snuff if it can't pass a load test. Very easy just to take it and have it load tested as batteries are often times the problem on light,fans not operating,starters,etc!

 

Mine would just click when I hit the starter button.
Turned out to be a dirty sticky brush in the starter. I took the starter apart and cleaned and lubed the brush and its been fine for 4 years now.

 

Ok so I went back to test the battery again and I got 11.62 volts under load for 30 seconds. Hopefully this eliminates the battery as the issue. I have already ordered the starter, solenoid, and thermal sensor so I am still planning on replacing this items. Hopefully I will have it running this weekend.

 

I just wanted to give an update on my situation. I replaced the starter, solenoid, and thermal sensor. The first issue I was having was the quad would not start unless I used the pull start. Now the quad fires right up with no problem. Secondly it was overheating and the fan was not coming on. That is now fixed as well. Rode the quad for a few hours last night with no problems at all. I know a lot of people have problems with air pockets when filling coolant. So far no issues with that for me. I just kept filling the radiator and allowing the air to bubble out then kept adding more when it got low. I did this over and over until the coolant level stayed at the top. Thanks so much for everyones help and advice. Happy riding!