Hello, i'm new to the forum. I have a 06 sportsman 800 efi. The problem I'm having is it wont start. It tries to and kinda does but it sounds like it is out of time. I ran the diagnostic test and it is code 21, loss of synchronization. Im thinking its the crank position sensor. I ordered the OEM service manual cause i dont have a lot of experience working on the efi systems. I was told the motor was rebuilt about a year ago. Does that sound right and if so is there a way to adjust the sensor or do you have to replace it? Any advice would be much appreciated.

 

Code be a crank sensor problem as they have gone out or I've had shorts in the harness going under the throttle body. If it grounds to the engine it wont crank.A lot of the problems were t bap sensors harness problem because of the thin wires and connectors.Look at the "sticky" above this section on 700/800 efi problems,plus it has a link for stronger repair kits than the crappy Polaris ones,if this is a problem also. Plus codes are not always completely accurate on the display.. Loss of synchronization is one of the common bogus ones.

 

Thanks OPT. I pulled the spark plugs and they were pretty bad. I had very weak spark on one side but I put new E3's in it and crimped the plug boot a little and now Im getting good spark on both cylinders. I pulled the flywheel, the key is intact. I disconnected the TBAP sensor and turned it over and no change at all in how it tries to start. Would the TBAP sensor not let it start at all? Also, this was a mud bike and I know this guy submerged the electronics. Im thinking my next move is to unplug all electrical connections and goop them up real good with dielectric grease. What are the symtoms of a bad ECM? This thing is so close to starting but something is just not quite right.

 

Being a mud machine,then by all means clean and dielectric grease the connections.May or may not start with the t bap disconnected,but will run crappy as it sends readings to the ecm on air pressure and the ecm regulates fuel mixture to the injection system. If after all you do and you can't get it started,then having it hooked up to Polaris Digital Wrench might be the best way to track down what's wrong. There's only so much you can do on efi machines with hand tools and a meter. All the sensors have to be right,fuel pressure must hold 39psi,no shorts in the sensor wiring or connectors.

 

How accurate is the Digital wrench? Also, the guy I got it from made the comment that the ECM was the possible problem. Is there any way to know that other than the wrench?

 

We used it quite often on problem machines. It's pretty accurate,plus the dealer can reflash(reset) the ecm if needed,plus it can find faults in basically all the systems from the ecm on down to ignition, fuel injection problems or sensors. Sometimes shorts are not always picked up,but it's still at times better to pay 1 hr diagnostic fee to find or eliminate the problem areas rather than pulling your hair out and throwing parts at it that may not be the problem!

 

If I get on your nerves with my questions just slap me up side the head lol. I sit up here all day at work thinkin bout what could be goin on with it. I was wondering, because Ive read that if you have a bad crank sensor you will have no spark. I am getting good spark on both cylinders, and as far as I can tell they are firing at the same time. If the sensor is bad would I have fire? Could it possibly be firing at the wrong time (which is what it sounds like to me) and another thing, it says to check the gap with a feeler gauge, but how would you do this cause when it is on the bike, the cover has to be installed and therefore there is no way of getting inside to see the gap tween the sensor and the flywheel. You have been more than helpful and I hope to let you know how well it runs soon.

 

Just look over this 2009 pdf service manual on the 800 and should help you a lot. Basically the same as your model.PartShark.com - Motorcycle Parts, ATV Parts, UTV Parts, PWC Parts, Powersports Apparel, Motorcycle Accessories for OEM and Aftermarket.
Plus here's a link on the 2006 700/800 service manual.http://gh-ftp.com/ORV%20Manuals/Polaris/Sportsman/2006/

 

Well last night I took apart every electrical connction I could find, cleaned with electrical cleaner, sanded all the little male posts I could and added dielectric grease. No improvement so far. It tries to start. I ve built racecar motors and it just sounds like it is 180 off on the timing. Backfiring thru the exhaust. I will say that the worst connector I found was where the crank sensor connected to the main harness. I cleaned it out best I could. Also, it looks like the plugs are firing at the same time and a buddy just told me that theyre not spose to but Im not sure bout that, I thought they are spose to and that one is just a lost spark. He told me to see i the ignition coil wires are shorting together. Could a faulty crank sensor be making it fire at the wrong time?

 

Pull the crank sensor harness and check the resistance. Should be around 560 ohms at room temperature.Plus check the flywheel for a sheared key.The most common cause on a lot of efi problems is the wiring itself. Especially the thin wiring on the tps and t bap sensors and the connectors themselves. Wires don't have to be visible broken,but can break internally and cause the backfiring,etc..