POLARIS GURUS - I Need Your Help

[CDK]

I have a very weird issue, sled will no longer start and I cannot diagnose it. I'm hoping one of you has seen my symptoms before. Please, no brand/part/ manufacterer bashing, pretty sure it's all been said before.

I was running my sled Fri night, and it was running great. It's a custom turbo project that I've put together, and I finally had it tuned and working. I parked it after running it in the field, light-moderate load on the engine, nothing crazy. Saturday, I fired it up, let it idle for 30 seconds, then switch to reverse and backed out of the shop. Hit the button to go back forward, and it died. Hasn't ran since.

Here's my setup, and bear in mind it was working damn near perfect when I parked it:

-2012 Switchback Assault
-RK Tek 858 Rev 1 kit, 12.5-1 cheater head
-Stock Pipe
-Boyseen Turbo Reeds, brand new
-Vipec ECU
-2012 Silber Turbo, downpipe, oil tank
-2013 Silber silicone charge tube, billet adapter with secondary injectors
-Turbo performance wiring harness with Map sensor, IAT sensor
-Factory Map used for BAP, tied to overstructure
-CPC rising 1-1 fuel pressure reg, set to 60 psi

I've torn into everything I can think of, trying to figure out why it won't fire again.

-Compression is 120 psi across both sides
-Spark plugs are good, pulled and grounded them to head bolt to visually confirm sparking
-Injectors are good, pulled the whole fuel rail and bench tested them to witness both spraying properly
-Motor has good vacuum, as tested by covering my intake pipe with the palm of my hand
-Vipec appears to be functioning propery. Logged in and tested injectors, fuel pump, kill switch, cold start maps, etc.
-If I spray fuel in the spark plug holes, it WILL fire for a few stokes, then die. This makes me think it's a fuel issue

I'm at a loss guys. The only thing I can think of is the injectors are not being told to fire during startup. Any thoughts??

 

[SRXSRULE]

Have you checked the fuel pressure? or tried to power up the fuel pump with an external power supply? If the pump isn't running see if it has power and ground to it when trying to start. You can also check the signal at the injectors to see if the ECM is pulsing them on. Its just a 12 volts on/off pulse signal to each injector. Eric

 

[CDK]

Have you checked the fuel pressure? or tried to power up the fuel pump with an external power supply? If the pump isn't running see if it has power and ground to it when trying to start. You can also check the signal at the injectors to see if the ECM is pulsing them on. Its just a 12 volts on/off pulse signal to each injector. Eric

Yes, I have fuel pressure gauge on the regulator, so I can confirm there is 60 psi when I start it. I actually toggle the ECU power before I try, so it primes the fuel pump to ensure I have full pressure.

Should be able to just unplug the injectors and stick a multimeter on the ECU plug, correct?

 

[mtnpull]

I had an ECM go out on one of my 600's and it was dumping too much fuel into the motor. Are your plugs wet and can you smell the fuel?

 

[CDK]

Ok, more testing:

The sled will fire for a couple strokes when you crank it over, but then immediately die. When it does fire however, none of the gauges or MFD light up at all, even briefly. This makes me think the chassis relay is NOT getting power when the engine fires. Does anyone have any advice on how to test VR's, stators, etc?

Does it make sense that the VR would be gone, and this is why the ECU isn't powering up and firing the injectors?

 

[TRS]

Did you have the flywheel off? Was the key installed or slipped out when flywheel was installed? Have seen one sheared also.

 

[CDK]

Yes I did recently. It was reinstalled when I reassembled.

Is there any way to tell if the stator is creating power while turning the motor with the e-start?

 

[TRS]

Did you have the flywheel off? Was the key installed or slipped out when flywheel was installed? Have seen one sheared also.

The flywheel will slip going from forward to reverse or vice versa. You have all the symptoms.

 

[TRS]

Yes I did recently. It was reinstalled when I reassembled.

Is there any way to tell if the stator is creating power while turning the motor with the e-start?

You could check timing marks in relation to piston location.

 

[CDK]

You could check timing marks in relation to piston location.

Do you have any tips how to do this? The procedure in the service manual references having the engine running, which is kinda out right now.

 

[TRS]

TDC the mag piston and the flywheel marking "0" should be in the window.

 

[CDK]

Got it, thanks TRS

 

[jerrydecoy]

I had a similar problem on my 11' turbo. Would start for a second or two and then die. No mfd or afr. I changed both v.r., fuel pump, stator and darn near all the other electrical components. My problem ended up being a bad connection coming off the capacitor. I'd darn sure look at every connection!


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[CDK]

I had a similar problem on my 11' turbo. Would start for a second or two and then die. No mfd or afr. I changed both v.r., fuel pump, stator and darn near all the other electrical components. My problem ended up being a bad connection coming off the capacitor. I'd darn sure look at every connection!

Thanks of the info JD, definitely inspecting the wiring with a fine tooth comb. I'm leaning towards electrical on this, as it's weird I don't see any gauges light up, even briefly.

Appreciate the reply!

 

[Stroker Customs]

I would check the mag sensor or crank triger to flywheel space. Should be in your service manual but I believe the spec is .030 to .050 clearance. One sensor is for forward and one is for reverse. They are very sensitive and will not pick up if they are to far away causing no injector pulse. I can look up the spec in the manual for sure if you need it.

 

[CDK]

Bumpity bump.

So I walked away from this for a while, but back at it.

I tried a new VR, that didn't help. Plugged in the factory ECU, doesn't run that way either. However, right after I tried that factory one, I plugged the Vipec back in, and it started running, for about 20 seconds then it died. It idled right up, and was running smoothly for those twenty seconds, then just up and died again. I did notice, the MFD and my other gauges did NOT light up while the sled ran briefly. The chassis relay does work when I test it with the Vipec on battery power, so I'm pretty sure it's functioning properly.

Is it possible my stator is shot, and isn't supplying enough voltage to get things firing? Is there any way to test it without the sled running?

 

[xc6rider]

Check all the connectors on the harness that the stock and vipec ecu plugs into?
Bad connection in their possibly made some contact while switching the two out?

 

[CDK]

I kinda thought that too, but I've looked at every connection, wiggled the harness, tried all sort of acrobatics while trying to start it. No luck.

The part I keep going back to, is why the MFD doesn't light up.....?

 

[xc6rider]

Checked grounds?
Tested stator?

Is it idling really low when it was running, or did it seem normal?

 

[CDK]

Checked grounds?
Tested stator?

Is it idling really low when it was running, or did it seem normal?

Grounds look good. Sled was idling at normal speed before it died again.

How do you test the stator with the sled shut off? I can't get it to fire again like it did before.