2008 dragon 700 start issue

[17cat]

I have been searching since yesterday for some definitive information. I am working on a buddy's 2008 Polaris dragon 700. Wont start at first until I prime the cylinders with a little mixed fuel. Then it fired right up and ran like a champ. Shut it down and did some preseason work on it and before I left the shop I started it again just to see. No problem, fired up first pull. Let it sit overnight and today it will not start again. So my question is ... is it most likely the check valve at the fuel pump? Is there somewhere else the fuel pressure can bleed off? Has great spark. Fuel filter doesnt seem likely because it runs so good once started also only 800 miles on the sled.

 

[17cat]

Just tried again and it fired after 12 pulls....

 

[retiredpop]

Possible bad chassis relay so the fuel pump not getting enough voltage to pressurize the fuel rail while pull starting? Once started the fuel rail remains pressurized for some time so it starts. You could probably check the fuel pressure to verify if this is the case.

This is from "Increasing your IQ" sticky at top of the IQ forum:

Chassis Relay: The chassis relay is activated by the
ECU at approximately 950 RPM. Below 950 RPM (700 rpm on the 900 cfi's), all
power supplied by the regulator / rectifier (RED circuit)
is used to power the ECU and fuel pump.

 

[17cat]

Thank you for the reply. I will see what information I can find on location and testing the chassis relay.

 

[17cat]

In doing some reading it sounds like the capacitor could be bleeding off and that may not leave enough power to fire the pump or injectors which would explain why it will start after 12 pulls. Please correct me if I am not on the right track? How does the chassis relay come into play with this situation? Is it a more likely problem than the capacitor?

 

[17cat]

Would the relay be intermittent? It started first pull today.... is the relay the one taped into the harness under the plastic cover? Is there a way to test the relay? I found the instructions on testing the capacitor.

 

[longvalley]

sounds like you have a plan but if that doesn't pan out try voltage regulator. caused weird things on one I had

 

[17cat]

Got some new information! I guess his wife was the one riding the sled and she just now told me that the gauges would go out and the sled would die, start run repeat....
From what I have been reading I am guessing it is the voltage regulator. Is there any ohm/volt meter tests to be sure? I dont have a manual for this sled. I did test the cap and it takes a charge and holds for a long time. Ten minutes now and only dropped .3 volts so far. Is the chassis relay still a possibility? How do you test that? The vr number is 4012476. There are no soft spots or blisters under the vr.

 

[17cat]

sounds like you have a plan but if that doesn't pan out try voltage regulator. caused weird things on one I had

That's what I am looking into now... see my last post, any info would be welcomed

 

[retiredpop]

The latest VR is part # 4013587. I did have to replace one of my 4012476 voltage regulators on a 2010 RMK 600 due to issues with lights. It did not have any bubbles on the underside either. For peace of mind I replaced the regulator on both of my sleds to the upgraded part number 401357 and have had no problems since. I was leary of buying an aftermarket regulator because I was not sure they manufactured them to the latest standard which protects the ECU if they go faulty. Attached is the ohm meter tests on the regulator. Make sure you set your meter to diode check mode as it states. FYI my faulty regulator tested fine so unless it is a total failure of the regulator it may seem okay. If the previous owner had the issues you found out about I would replace the regulator before it takes out the ECU.
The chassis relay should read 76 ohms across pin 1 and 2. You should see an open across pin 3 and 5 with relay in unpowered state which is what it should be in when pull starting. (When it operates then pin 5 gets battery voltage to feed chassis components.)
Found this statement in increasing your IQ sticky on this forum."I've also had a bad chassis power-up relay cause starting problems... stuck in the closed positon that caused problems. This allowed the little bit of power that was produced by the stator to bleed off thru the headlights and not allow it to start."

 

[dragona1]

I had a 2007 700 dragon. There is a thin metal ring on the inside of the magnets in the flywheel. It came loose and had rubbed through the insulation on the wires going in to the stator. I used liquid steel loctite to lock that ring into the flywheel and was good after that. Also if someone happened to zip tie the wire harness too tight over the throttle bodies they will short out from vibration. Both of these caused my mfd to flash on and off and go wonky.