04 800 Mountain Cat Bogging

woodtick · Dec 2, 2008

I had a like problem with a 02 800 m.c..I finally came up with a bad volatage regulater. My daughter noticed that the tack would go crazy when it would act up. The problem was very intermediate and would happen mostly under power situations. I had already checked everything out. The voltage regulater has three wires on it (I'm guessing you have a E.F.I. sled). so the red one feeds the servo motor. So the power valves didn"t work all the time. The voltage regulator converts ac to dc for the motor. But this only true on EFI units. On carbed models there is another type of voltage converter to do the same thing for the motor. Hope this helps out.

chsdaddy · Dec 2, 2008

Keep the sugestions coming guys I am adding to my list.

I assume I can just unplug the connectors coming form the side of the kill switch until it doesn't work, and the other 2 on that side are the thumbwarmer and handgrip warmer. What about the throttle safety switch?

I had a 72 ford 4x4 with a voltage regulator that went bad and acted similar but it was constant. Everytime I shut down the sled was for 5 minutes at least which I am thinking was enough time for something to cool off. It seemed like later in the day it took less time for it to act up, but still ran great for at least 60 seconds before acting up. I need to start looking but it's dark outside and I have a 1hr commute and I am still at work. UGGH!

This site is an enormous wealth of knowledge. My buddy and I were commenting this weekend on how evertime we stopped people who saw a hood up from a long ways off would make an effort to chack and make sure evrything was okay. Snowmobilers are a good group.

I got rid of the carbed sleds cause i thought efi was going to be easier!!

Rixster · Dec 2, 2008

I am betting that it is going into limp mode. If you can get the sled to do it again, try shutting it off and starting it right back up. Should run for a minute or two then goes back into limp mode.

chsdaddy · Dec 2, 2008

Limp mode means that the ecu has detected a problem??? and I should see something on the check engine light???

Didn't know about limp mode, but that is exactly what it feels like.

I found a place on ebay to download a service manual, anybody done this?? Says it is good for all 2004 models. Is there more technical info in there like fuel pressures, voltages at various components etc??

woodtick · Dec 2, 2008

The plug you are looking for has a purple wire a blackwire with a white stripe and a brown wire. Just unplug it and it will kill the stop switch and the throttle safety switch. The sled will still operate but will need to be shut down using the key.

arcticridr · Dec 2, 2008

Im with Rixter on the rubbed wire thing, was a problem on 04-05 protected the wire harness on my 05 KK before it was ever fired up, that and check your ground by the recoil they have a bad habbit of comin loose, the wires we alluded to come up past the oil resevoir and thru the aluminum standoff, the edges of the standoff are pretty sharp and do a number on the harness which comes from the stator, pretty important harness, next would be kill switch/safety switch prolly the next most common problem. Check your plugs coming from the Ecu/stator , if you notice white corrosion clean all the connectors and put some dielectric gel on all of them. Not as big of a deal on these as the 05 m-7's but look at your taillight wires under the seat can also rub thru!! Let us know what fixes it !!!

:beer; Oh yea the ethanol wire enriches the fuel map by bout 3% for the ethanol, unplug it to be safe when runnin ethanol!!!!

arcticridr · Dec 2, 2008

"Limp mode means that the ecu has detected a problem??? and I should see something on the check engine light???"

Yes but if its like the 05's the light will be under the ECU, they usually put a piece of reflective tape under the L.E.D. so you can see it when it flashes, and the codes are normally on a sticker either on the ECU or the air box, I dont think the dash light/symbol/wrench flashed till the M sleds ??:beer;

woodtick · Dec 2, 2008

If it goes into limp mode it will not run up in rpms. There is a small led light on the bottom of the ECU. If at start up it blinks once it means the system is operating properly. If it blinks more than one time then there is something wrong. If it does I can find out what is possibly wrong. There should be a section in your owners manual or somewhere on the sled that will explain what each series of flashes mean. If you can not find it let me know.

jhdadoland@bresnan.net

chsdaddy · Dec 2, 2008

Found the chart that talks about the check engine light in the manual so I will check that out on the ecu if I get nothing on the dash. Also will run it in the dark, have found crack ignition parts that way before. I did monkey around with the seat a lot after I got it, I made a custom seat and reupholstered so maybe a piched wire there. I'll find it just need to keep at it.

Rixster · Dec 3, 2008

I am pretty sure your light will NOT be on the ecu, that wasnt till 05. Yours should be the temp light on the gauges.

chsdaddy · Dec 4, 2008

Ya I looked for a light and couldn't find one blinking any way, it was dark so thought that would make it easy to see. I unhooked the kill switch plug and no difference.

What rpm should these top out at? I have it lifted off the ground so the track spins and when I pin it, it will hit about 8000 for a split second and drop back down to just over 7000. On the trail it would barely hold 6000, but that is with a load so that seems about right to me.

Based on all of your input here is what I think may be happening:

Like many off you said the APV is not working so I will tkae that apart and amke sure it is clean and properly adjusted. Next would be the servo that operates the valves. Next the voltage regulator, and next the magneto.

I also think if the volatage regulator is bad or going bad it could affect the fuel pump and will check that pressure as well. Any one know what it should be?

Thanks.

ZRrrr · Dec 4, 2008

I do believe that the rpm's should hit about 7200 with a climb to about 7400. If your dropping to 6000 under load I would suspect that's why you bog. A clutching issue. Set up right that sled should pull peak rpm's all day long no matter the load. My 800 does. Just my opinion.

Rixster · Dec 4, 2008

6000, Sounds like your power valves are not working. Either they are stuck, or your servo motor isnt working. My bet is that your wires are worn through under the oil tank and the one that powers your servo motor is grounding out.

woodtick · Dec 4, 2008

Your test up on a stand isn't a very good test. Hard to tell if things are working properly due to no load. If you want to you can take the cover off of your servo motor. Then I believe your power valves should open at about 6300 rpms or so. The little wheel will rotate clockwise at about this speed. Also you can check to see if they are stuck be removing the clip under the wheel and remove the cables from wheel and pull them one at a time. You will have to rotate the wheel counterwise a little to get them out of the slots. There should be a measurement for the cable lenght in your owners manual. If this is incorrect it will affect the way they work, also. When this is done just put them back in the slots, put clip back on and rotate untill tight, servo will self center when you start the engine.One cable curve at the servo is a little longer than the other one, this is to make them fit better.. You can also try amother test. You can pull the cables out all the way and fix something to hold them out then try a run. They operate to give you low end and high end power.But sounds like your having troubles on the high end. If this cures the problem then it is the power valves. Kind of long winded but maybe.

chsdaddy · Dec 4, 2008

Well I checked a couple of things:
I pulled the oil tank out of the way and looked at the wires as best as I could. One of the wires going back to the tail light was worn but didn't look like it was worn through. While the oil tank was out of the way I found the led on the ecu and I am getting no flashes. To make sure it was working I unplugged the TPS and it flashed 1 time continuously for an open TPS. I noticed it didn't seem to run any different though. The APV servo rotates freely at about 7000rpm. I measured the cables and they are both about a hair over 39mm. The spec says 38.5 +/- 1mm. When I pull on the cable it moves freely and the springs pull it right back. The manual says at high altitude (I am at 6500ft now, clutched for 9000+) the servo should rotate at 6900rpm, and max horsepower is at 73-7500 rpm. If I pin the throttle it jumps to 8000 for a second and then drops to about 7200. If I pump the throttle I can get it over 8000 but with no resistance on the track shoudn't I have to keep it from redlining?

The last thing I noticed and maybe I am a complete idiot is th throttle cable seems to have more slack in it than it should, so I am going to check that tomorrow in the daylight. I am also going to pull the pipe and can and thoroughly check wires. There's a lot of places for rubbing to occur.

woodtick · Dec 4, 2008

The fuel pump has its own power coil on the stator.both wires are orange in color. There should be a plug up by the headlight with a yellow and brown wire. You can check there whether the stator is working.i will state again the trouble i had was very intermitent. The tack would jump all over when it (voltage regulater) wasn't working properly. Aren't electronics fun? I hope you get yours fixed before the two months it took me to figure my daughters out.like i said it was a hit amd miss problem.we could run it flat out on the flat with not much problem but as soon as we put it where we really needed the power it would fall on its face. And it was the voltage regulator and every time it would the tack would act up. So one day on the trailer i started it and the tack acted up so i got out the test meter and fould i had only5 volts and none at the servo motor. I had tested the stator,voltage reg. Servo motor,took out thwe entire wiring harness,checked everything i could think of.but all checked out fine.untill that one day. This process took me about 2 months. Again ain't this fun!!!!!!!!!!!!!

chsdaddy · Dec 4, 2008

Well out of all the elctronic parts the voltage regulator is the cheapest, I should probably just buy one. I can't believe the TPS is not replaceable, you have to buy the whole throttle body. I am going to have some time this weekend to look at it so I will keep you all posted.

I got a service manual so if anyone needs anything for a 2004 let me know and I can pdf the pages for you.

chsdaddy · Dec 5, 2008

Okay, I pulled a lot of stuff out of the way and traced down wires and couldn't find any problems. I adjusted about 1/2" of slack out of the throttle cable and put it all back together. I fired it up and let it warm up and now I can get many more rpms and hold 8200, which is probably more than enough with the track free. But as I hold at different lower rpms there is a definate miss if you just try to maintain a certain throttle position or rpm but it gets rpms without a problem and wraps out just fine.

I tested the fuel pressure and it would hold 46-47 at idle drop to no lower than 45 and when I pinned the throttle it went to about 49 and then I broke a belt, WTF would cause that. Maybe I am just not cut out for the power. We have 2 snoscoots, maybe I should spend a season on one of those!

Would the miss be because of a faulty TPS? In the manual it says you cannot service them and they are not replaceable but there are 2 screws holding it on the throttle body, can you replace that part or do you have to replace the whole throttle body?

76FOMOCO · Dec 5, 2008

yes you can replace it, did you check the valves? this is a big problem with them......sounds like your on the right track...

diggerdown · Dec 6, 2008

You have to put a load on it to test it out. Free spinning on the stand can make the R's bounch all over!

04 800 Mountain Cat Bogging

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