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Rush 600 running on one cylider

Rush600

Rush600

New Member
Messages
19
Age
34
Location
Michigan
Country
USA
Years Snowmobiling
20+
Snowmobile
2010 Rush
This is not an Axys, but I this area gets much more traffic and I am hoping to get some answers for those smarter than me on the CFI system! This is a 2010 Rush with the 2+2 system.

This is a fresh full rebuild, and I bought it with the PTO rod snapped in half and the case totally ruined.

When cold, the sled will high idle (about 3400 rpm) and run stronger on the PTO side. If I pull the PTO cap, it obviously idles down as it is now running on one. But, when I put the PTO cap back on the cylinder WILL NOT pick back up until I give it some throttle. I have attached a video.

When it's warm, it just runs on the mag side until you give it some gas.

I got it warm and did a couple laps in the yard, at approximately 10% throttle the PTO side kicks in and it runs on both.

My guess is there is an issue with the low speed PTO injector, either the injector itself or electrical.


Here is a list of what I have checked/done:

Injectors were cleaned and flow/ohm tested. I tested the ohms in the harness as well.
TPS was checked
New sock and inline filter, pressure is 60 lbs.
I have swapped plugs.
.020" throttle cable pay and the blades are resting in the stop.
Compression is good at about 130 lbs
Reeds and boot were inspected and were good
It seems all connections are plugged in
With hood on there is no check engine light

It almost seems like and air leak at first, but I am baffled as to why it runs on the PTO side, then won't pick back up. It runs good/normal when it does run on two, but I am not the kind of guy to take of riding when it runs like this.


Here is the video.

 
There is a vacuum leak on the PTO side. Possibly where the case halves meet or the PTO crank seal is leaking. I assume the PTO crank seal was replaced during the overhaul, but still check it.
Try spraying starting fluid or carb cleaner around that area at idle and see if rpms pick up.
 
rabbi said:
There is a vacuum leak on the PTO side. Possibly where the case halves meet or the PTO crank seal is leaking. I assume the PTO crank seal was replaced during the overhaul, but still check it.
Try spraying starting fluid or carb cleaner around that area at idle and see if rpms pick up.
Click to expand...

Thanks Rabbi, I forgot to put that on my list. Sprayed carb cleaner behind clutch area and no difference.

EDIT - I am going to try spraying the case seam as well and see what happens. I hit the seal area pretty good and saw no difference. But, this sure does seem like vacuum leak.

Does it seem normal that it runs better at higher rpms? I have only seen this once on a XC700 (bad crank seal) and it would never run on the PTO cylinder unless you sprayed the seal with carb cleaner.
 
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After again spraying with starter fluid and no results,
I'd pull the air box n squirt fuel in the dead side t body n see if it picks up the cylinder or not (running warmed up). I agree it sounds like a vac leak but could be running so lean it doesn't know whether to shit or go blind, confirm if fuel makes it pick up first.
I'm also assuming you've replaced plug end caps regardless of how they look? Same goes for ohm'd coils out?
 
Unfortunately I think Rabbi was correct. I let it warm up to where it would idle down and run mainly on the mag side. Sprayed the front PTO seam with carb cleaner and the rpms jumped up. I REALLY wanted him to be wrong! I took my time with this build and thought i did everything right. I cleaned and cleaned the case mating surfaces until they were perfect too. Not a spec of old sealant anywhere. Cleaned the work area and took my time. When I was younger I would rush everything and work in a mess with tools everywhere, and I never had crankcase leak! Bottom line, I guess I was light on the Yamabond. I will blame my buddy as I normally use Motoseal, and he talked me into using his Yamabond. LOL

Okay vent off. Nothing I can do now but laugh, have a beer and get prepared to start over as I watch the last of our snow melt. :Banghead
 
At least you know what the problem is now
 
Yamabond is a terrific product for case halves. After cleaning, to ensure sealant bonds hard to the cases, I wipe first with lacquer thinners until spotlessly clean.
Upside, you've figured out the problem before you ran it long enough to hurt it.
 
I am just pissed as I thought I did everything right. Hell, when I was a "kid" I never used a torque wrench. Maybe that was why I didn't have issues as I over tightened everything. LOL
 
ZR SLEDHEAD said:
Yamabond is a terrific product for case halves. After cleaning, to ensure sealant bonds hard to the cases, I wipe first with lacquer thinners until spotlessly clean.
Upside, you've figured out the problem before you ran it long enough to hurt it.
Click to expand...

I agree Yamabond is great. But I need to blame someone so I am blaming him. LOL

The thought of starting over makes me cringe!
 
Yea but starting over because you broke it would suck harder.
We've all had an "opps" moment.
 
ZR SLEDHEAD said:
Yea but starting over because you broke it would suck harder.
We've all had an "opps" moment.
Click to expand...

True. I was very thorough so it is disappointing. Do you guys torque to factory specs? I always thought they seemed light.
 
ZR SLEDHEAD said:
Yea but starting over because you broke it would suck harder.
We've all had an "opps" moment.
Click to expand...
Yes we have!
I did a complete overhaul for a buddy on an XC 600 (obviously carbed). He insisted on helping, so you can see where this is going. Long story short, I got it all assembled and installed in the sled. The fuel pump hose routing was a nightmare. I normally take pictures, notes, tag hoses, etc. But with the owner "helping" the engine removal got rushed. This sucker wouldn't start, no fuel to the carbs.
The inlet hose got switched with a discharge line. After I found and corrected that snafu, we got the engine running and held the rpms up to initially get everything lubed. Then, the engine wouldn't idle down, and when it finally did, it was way too lean at idle. I questioned the carbs, whether the idle circuits were plugged. I finally found the problem, the crankcase drain plugs weren't installed. My buddy assumed I had installed them and I thought he said he did. Put in the plugs, good to go.
The sled ran great and has gone several thousand miles with out a hiccup.

My buddy and I laugh about it now, but how frustrating it is when you are going through it. In then end, shit happens to all of us sooner or later.
 
Well I figured it out. I am embarrassed to say that I didn't notice the throttle body boot had a good sized dent in it on the pto side. I checked the outside thoroughly but never looked at the inside. At least I didn't have to tear it down!
 
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Here is a pic of the boot. I can't believe I didn't notice it. Held it up to the light, blew it off with air and shot it with WD 40 before putting it on and never saw the dent.
 

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This is how I found it before taking it apart. About $20 from home depot for everything. I will never finish dressing an engine without pressure testing it again!
 

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