Thank you OPT for the replies to my direct mail. Am posting as it may assist others now that I have figured out how to post.

POST: My 2006 700 EFI started overheating last week on my first ride with it. I have read several threads and have done the following so far.
1. I have tested the thermostat in boiling water(opens ok)
2. I have tested the thermistor sensor on left side of by thermostat housing (by heating and ohm meter)
3. I have replaced radiator cap (13 lbs??), and have run for at least two fan cycles with front end raised and then each side raised to purge.
4. I have connected directly to fan and it will run continously.

PROBLEM: I have noted the fan will only cycle two times and then overheating occurs causing spewing from resevoir.
When this happens the fan will not come on even when I disconnect from the thermistor sensor, if I disconnect when cooled down the fan will come on.
Several posts have talked of a temp sensor on radiator but I can't find one on either my 05 or the 06.
ECM maybe?? Is the ECM the Bosch unit under front pod or the silver unit in front of radiator?

Replies from OPT follow:
1. The ECM/ECU is the Bosch unit. The control module in the front does operate the fan and a few other functions. Most of the time it's still trapped air that does take awhile to purge,but the sensor can be faulty also.(You can check the resistance when hot and cold on this sensor, resistance should go down as it gets hot) Located on the drivers side on the side of the cylinder. One other thing that rarely happens is the water pump impeller itself. If too much trapped air is in the cooling system,they can heat and actually melt. Try to purge again,may take several times to do this to get all the trapped air out. OPT

2.The fan should come on if you pull the sensor wire on certain models(mainly the 800 efi) Not all fans will come on! If the fan only cycles once then you could have a controller module problem(located at front) I did have to replace a few of these as they are subject to water contamination which isn't too good on the resistors etc. Plus run power to the fan motor itself to eliminate it as the problem. OPT

Any other ideas appreciated

 

Sorry!Thought you had a 500 efi from your pm! Still try to purge the system,may take several times,plus checking the water pump impeller for any heat related damage may be an option. Plus there is a resetting fan circuit breaker taped to the harness on several models of the 800 efi leading to the fuse block,not sure on the 700 though. I'll check through the pdf I have to see if anything else I've forgotten. Plus one of the simple overlooked problems is that the battery itself must be good or can cause problems. Plus the radiator must be clean front and rear especially around the rear by the fan assembly. This is where a lot of dirt/mud gets trapped causing overheating problems. OPT

 

Just checked the impeller. It appears like new.
Radiator is totally clean.
Will check for resetting fused taped to harness.
There are 2 20amp resetting fuses right in front of the ecm under the headlight pod along with 2 smaller ones.
Thanks again OPT, really appreciate the input.

 

Check also that the fuse block itself (you can remove the screws and check under it) has good wiring connections to each fuse.Plus wouldn't hurt to use a little electrical grease in the fuse block. You can swap around the 2 relays(as they are the same) one is the main power relay,the other is the fan relay just to check this out. On the schematic,it shows and orange/black wire is powered to the fan motor from the fan relay. The fuse block has a 6 amp speedo fuse,15 amp efi power fuse,20 amp chassis power fuse and a 20 amp accessory power fuse. PLUS since you've pulled the water pump cover, make sure you have the front tires off the ground when you purge the cooling system again! The way these hoses are routed,it does take several times for the fan to cycle on and off to purge all the air out of the system,plus you can squeeze the hoses to help while it's running. After you're sure all the air is purged you can top off the radiator,replace the cap and top off the overflow bottle. Still not sure if there if is a small metal circuit breaker taped to the harness on this model. OPT

 

With front end jacked up off my ramps I finally got a big burp out and fluid level remained fairly constant BUT the fan would only cycle twice and then I would need to direct wire to run the fan.
Let cool for a couple of hours and fluid was still right to the cap so I started and fan came on again just as fluid was ready to spill over. Fan ran only twice again.

 

Sounds like the fan is short cycling because of either a relay(did you switch the two relays around?) or the orage/black wire from the relay might be shorting out that powers the fan. The 2005 700 efi pdf manual I have still shows a 20 amp thermal circuit breaker that allows power to the fan relay and is taped to the harness just before it gets to the relay/fuse holder area.I'm just not sure if your model still has this thermal circuit breaker,but sure sounds like a few we encountered in the shop. They were 15 amp breakers and triggered,not allowing the fan to operate very long. We swapped em out for 20 amp breakers and solved this problem. The breaker would look like this.Plus "if' you have one any auto store has em for about 6 bucks. Polaris New Circuit Breaker 20 Amp Electrical Taillight Sportsman Predator | eBay
The listing on the add does show your model to use this breaker,but may not be accurate? OPT

 

Thanks OPT. I did exchange the two 20 amp in the block.
Would breaker your talking about be in a sealed vinyl pouch secured to wiring with a wire tie? I did find one of those and wondered what it is.

 

Could be on your model! That's how they usually are,sealed in a plastic pouch! It was a bare circuit breaker and taped on the harness on the 800 efi models that we had problems with though.This to me was an after thought on Polaris's part! You can split the pouch and see if the breaker terminals are corroded. This is what happened most of the time on these breakers,plus they can short out when hot also. OPT

 

Thank you! Will cut open in the morning to check. How should I reseal?

 

All I did when I changed one out was to squirt a little silicone or electrical grease in the pouch over the connections and used electrical tape around the pouch tightly. Hope this is what's wrong. Keep us updated. OPT