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My 08 summit 800r cuts out badly whenever I give it throttle. I've been through the carbs inside and out numerous times, changed jetting, needle clip position, etc. It starts and idles fine but when you crack the throttle just a bit it starts sputtering and cutting out. The plugs are wet when I check them that's why I've been through the carbs so many times but I've yet to find anything wrong. I've checked the coil and stator and they seem good. Compression is good on both cylinders too. Now I'm wondering if it's a spark issue? Bad ecu? I checked the relay but my understanding that it deals with the lighting system. I don't know where to go from here any suggestions would be appreciated.

I should mention too that I have an AFR gauge and it reads 14-14.5 at idle and when it starts cutting out it's reading 11.5-12.5.
 

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Did you have a good look at the reeds when the carbs were off?

It might be a case of weak spark alright, maybe try observing a spark tester that can be used while the engine is running.
 

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Discussion Starter · #3 ·
I have Boysen reeds and they look like new. I'm not familiar with spark testers what kind do you use?
 

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They're just a simple tester I found in an auto parts place. You connect the lead to the tester that also attaches to the plug.

That way you can see the spark in action.
 

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Ok so I tested the stator, examined the ecm connections and pins, tested the tps, throttle position sensor, and it all checked out. I'm running out of options but one thing I need more help on is resetting the tps. The manual says to reset whenever the throttle cable is removed, well I pulled those carbs and removed the cable numerous times with no detrimental affect but who knows maybe now that's it. Anyway I've searched on here and found numerous posts on how to do it without BUDS. Here's the jist of the procedure I'm following:

"Locate your diagnostic port attached to chain case. Power up both red wires 12v+ and ground black wire 12v - the gauge will power up and cycle. When the gauge completes its power up sweep of the gauge needles hold throttle to the bar then hold "hot start" button about 5-10 seconds or so until engine light comes on. When the engine light comes on your done and can disconnect the power to the gauge."

My machine doesn't have a "hot start" button, and I'm not sure what that is, so I've held the throttle and pressed the start/rev button and waited but no check engine light ever came on. What am I missing? Also do you think resetting the tps would cure the no rev problem I'm having? Or will I have to take it to the dealer to have it done with BUDS?
 

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Agree with DESS suggestion. What rpm is it cutting out at? 3000 perhaps?
 

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Thanks for the suggestions. As for when it cuts out, it starts and idles fine, so sometime after clutch engagement around 4k, I ease on the throttle and start to move and I can tell it starting to mis then I press more and at 1/4-1/2 throttle it starts missing and cutting out and won't rev any higher.

My next test will be the DESS key and DPM.

Does anyone know if I unplug the throttle position sensor will the machine run? I'm going to try that and see if that reveals anything. I still haven't gotten an answer if resetting the tps could be an issue.
 

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Do you have any beeps or flashing lights? That may indicate a tps or other problem.
I think the general consensus for tps is that it shouldn't need reset as long as sled wasn't run or tried to run with tps unhooked. I've unhooked the tps on my 07 a bunch and not had a reset issue.
 

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Since I can rev above 3k and I get 2 short beeps on startup I'm guessing it's not the DESS and I shouldn't have to dig any deeper on it? No other beeps or flashing lights. So what do you think about running the sled with the tps unplugged? Like you, I've had my tps unplugged many times with no issues.
 

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Ok so I tested the stator, examined the ecm connections and pins, tested the tps, throttle position sensor, and it all checked out. I'm running out of options but one thing I need more help on is resetting the tps. The manual says to reset whenever the throttle cable is removed, well I pulled those carbs and removed the cable numerous times with no detrimental affect but who knows maybe now that's it. Anyway I've searched on here and found numerous posts on how to do it without BUDS. Here's the jist of the procedure I'm following:

"Locate your diagnostic port attached to chain case. Power up both red wires 12v+ and ground black wire 12v - the gauge will power up and cycle. When the gauge completes its power up sweep of the gauge needles hold throttle to the bar then hold "hot start" button about 5-10 seconds or so until engine light comes on. When the engine light comes on your done and can disconnect the power to the gauge."

My machine doesn't have a "hot start" button, and I'm not sure what that is, so I've held the throttle and pressed the start/rev button and waited but no check engine light ever came on. What am I missing? Also do you think resetting the tps would cure the no rev problem I'm having? Or will I have to take it to the dealer to have it done with BUDS?
That procedure is only for a 600RS race sled, but you may be on the right track with the reset, I don't know. For this type a problem I probably would bring it to the dealer.

By the way, what section in the manual did you read about a reset needed after removing the throttle cable? ..... Never mind, I just realized that you have been following a Race Manual instead of a Shop Manual.
 

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Discussion Starter · #15 ·
So I checked the dpm solenoid and heard it click so I'm going on the assumption it ok, I didn't do any beaker/water test.

I unplugged the tps, started it and ran it around a quick loop and it still runs like crap. I watched the tach and it starts misfiring about 4500. Increasing the throttle I get it to 5k then 6k and the tach is jumping wildly 200-300 rpms up and down, all the while misfiring and popping.

I haven't tried the spark test yet and that's my last hope then I'm taking it to the dealer and have the hook it up to the computer.
 

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You will need to do the water test on the DPM, I have had the solenoid test good but dpm leaked or you can replace the O-rings in the DPM

I would also check Check the voltage regulator wires

Campaign no.: 2008-0016
October 3, 2008 Subject:REV-XP Wiring Harness Issues
No. 2008-20

PROBLEM
On some of the above mentioned vehicles, electrical
irregularities of an unknown source may be experienced.

SOLUTION
This bulletin gives troubleshooting steps in order
to quickly locate and repair electrical irregularities.
The following repair procedures must be completed
as per this bulletin:
- Voltage Regulator Wires Chafing
- Maintenance on Countershaft Support
- Taillight wires chafing
- Cluster gauge issue.

Voltage Regulator Wires
Chafing
Vehicle Preparation
1. Remove RH side panel from vehicle.
2. Remove muffler springs
3. Removemuffler from vehicle.
4. Remove acoustic panel from vehicle.

Voltage Regulator Wires Repair
1. Inspect voltage regulator wires for chafing or
cutmarks and repair if necessary.
2. Reroute voltage regulator harness toward the
top.
3. Attach voltage regulator harness on oil injection
line using a locking tie
4. Clean rivet area using pulley flange cleaner
5. Apply silicone to cover rivet.

NOTE: Make sure to properly cover the rivet to
eliminate any sharp edges or protrusions that
could damage the voltage regulator wires.

Taillight Wires Chafing

NOTICE Taillight lens is held in place by two
plastic pins inserted in rubber grommets. If
lens is forced too far sideways when removing,
the lensmounting pins may break and lens will
have to be replaced. Do not pull lens out too far
to avoid damaging wiring.

1. Remove taillight lens by carefully pulling on
lens at both ends.
2. Rotate bulb holder counterclockwise to remove
it from lens.
3. Carefully pull taillight harness toward the rear
of vehicle.
NOTE: If the lens does not pull out far enough to
work on, the locking tie for the taillight harness under
the fuel tank may have to be removed and the
harness laid down in the tunnel channel. Refer to
the following steps:
- Remove fuel tank side trim panels.
- Remove fuel tank side retaining nuts.
- Remove fuel tank side shoulder bushings.
- Slightly lift up rear part of fuel tank.
- Cut taillight harness locking tie.
- Stretch taillight harness in the tunnel channel.
- Reinstall fuel tank shoulder bushings.
- Secure fuel tank side retaining nuts to 33 N•m
(24 lbf•ft).
- Reinstall fuel tank side trim panels.
4. Pull protector tube toward the bulb holder to
protectwires.
 

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Discussion Starter · #17 ·
So I ended up taking to a good guy who does works for the dealership out of his own shop. He hooked up the computer and went through all the electrical and the only thing he found was the dess cord needed replacing. That didn't solve the problem however. What he did find was signs of coolant in the mag side cylinder and coolant on the outside of the block but he couldn't tell where it was coming from. We were wondering if it could be coming from an internal leak from the heated carb system on that side being that the machine starts and idles fine and only starts acting up with more throttle thinking that the coolant is getting injected when there is more velocity in the carbs? Anyway I'm bringing it back home and going to look into that more and maybe get another set of carbs to try.
 

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Discussion Starter · #19 ·
So I did a leak test from info on this site and determined that the outer crank seals are holding pressure but I was unable to perform the inner crank seal test as outlined in part because my 08 motor didn't have the one elbow the 600 motor did. Any suggestions on how to test the inner seals with the motor in the chassis?
 

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When you tested the outer seals, if you would have had a significant problem with the inner seals you would have seen bubbles coming up the feed line to the oil tank, usually leaking inner seals are more a oil entering the crankcase causing oil fouling.... sometimes those stators test good but are still prone to act up especially when warm...
 
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