04 800 Mountain Cat Bogging

jsoutdoors · Nov 29, 2008

This sled is new to me. Today went out for the first time and the sled ran like a top for 45 min. It then started bogging at about 6000 rpm and acted like it wasn't getting any fuel. In the process of checking everything I pulled one of the spark plug wires out of the boot. I cut the insulation back and jammed it back in there and the sled will run normal for about 60 seconds and then cut out and bog down. I changed the plugs checked the fuel vent hose etc. Whats wierd is it runs great for about 60 seconds and then craps out. Like I said it acts like no fuel but also seems like an electrical problem, I don't know why I say that but why would it run great and then bog down? Any suggestions on what to look at first???

jsoutdoors · Nov 29, 2008

I was looking at the sled and on the ECU?? there is a sticker that says to disconnect a wire for oxygenated fuel. At our gas station we buy E10 (10%) ethonal. Would that make it bog??? It is conected for regular I think??

jsoutdoors · Nov 30, 2008

Is this fuel designation wire Brown and white? What does it tell the ECU to do?

76FOMOCO · Nov 30, 2008

efi or carb? check the pickup in the fuel tank. also check the power valves to make sure they are not sticking and the cables are in good shape and to the correct 34.5mm of free cable.

miko · Nov 30, 2008

76FOMOCO said:
efi or carb? check the pickup in the fuel tank. also check the power valves to make sure they are not sticking and the cables are in good shape and to the correct 34.5mm of free cable.

ditto!

diggerdown · Nov 30, 2008

You have to check for spark when it quits. Once you know if it is fuel or spark you have a place to start from. If spark is the problem you probably have either a stator or coil going out. Both will heat up quickly and lose continuity. It sounds like it is efi so you also have your temp and air sensors affecting the running. Fuel problems can be fuel pump, pickups, water, fuel pressure regulator and ecu. There is a diagnostic light on the back of the box that will flash a code to give you some sort of dirrection. When you put a plug cap on you should twist it on and not just push it in. If you just push on it, the probe can push the wire back, instead of sliding into the middle of it.

chsdaddy · Nov 30, 2008

76FOMOCO said:
efi or carb? check the pickup in the fuel tank. also check the power valves to make sure they are not sticking and the cables are in good shape and to the correct 34.5mm of free cable.

When I looked in the manual it says 41.6-42.6mm, 8mm is almost 3/8 of an inch. Does anyone know what is correct for a 2004 800EFI?

I checked the fuel pump pickups and they were clean the fuel pump is recirculating in the tank but I don't know what the pressure is. When bogs it will run great, normal over the entire rpm range for about 60 seconds and then start crapping out, surging to 6000 rpm and dropping down, up, down, up, down. At one point heading back I was able to really feather the throttle and maintain just under 6000 rpm, but it was hard to do.

76FOMOCO · Nov 30, 2008

pull the valves and check them to make sure they are clean and not gummed up, check the cables to be free for play and damage. take the cables and adjust them until there is no slack at the servo, but not tight and take a measurement this should be real close to what the spec should be.

Extreme-One · Nov 30, 2008

Check to make sure one of the fuel lines aren't pinched. I pulled the throttle bodies off my sled once and put them back on pinching a line. It would run fine at idle and then die like you mentioned. Checked everything and finally found the line pinched.
On a second note, I'd replace that spark plug wire with a new one. The EFI's were finicky about that.
If the wire is connected then it is setup for non ethanol fuel. Disconnecting it will make it run richer if you run ethanol fuel and leave it connected it will run lean.

Good Luck...

chsdaddy · Nov 30, 2008

Yeah I have a lot of stuff to check and started with the simple stuff on the trail yesterday. I won't get to it until tomorrow, but I am sure I will be back with questions.

I started looking at the price of some of these parts and I might be better off parting this thing out and buying a new one!!! 1200 for an ecu, 450 for a magneto, 110 for a coil and 2 spark plug wires. Is there a cheap parts place some where online?

m8inthemtns · Nov 30, 2008

Did you try running it with the throttle safety switch disconnected? This was the last thing I checked when I had similar problems. Took care of it.

chsdaddy · Dec 1, 2008

m8inthemtns said:
Did you try running it with the throttle safety switch disconnected? This was the last thing I checked when I had similar problems. Took care of it.

No I didn't, where is the throttle safety switch?? or is that like the key to the batter's box, or the circular square . . . . LOL!

CATSLEDMAN1 · Dec 1, 2008

Throttle safety switch and kill switch

Both the kill switch and throttle safety switch when mashed or full of water or.......broken can give you the symptoms you are experiencing. If I recall we had to disconnect both years back on my friends sled, he's big and strong and liked to throw the thing around and grabbbing throttle and gripping bar to throw the sled to the left, he would cause it to go into the missing poping won't run mode.

Also blow out plug caps with air and get rid of black cat dust, also make sure your not overheating......low coolant / low snow on trail/ no snow flat.

Rixster · Dec 1, 2008

Do you get an error code? (temp light flashing x amount of times). Sounds like the same thing lots of guys have had. Pull your oil tank out of the way so you can se the wires that go under it. They rub on the bulk head a wear through the insulation, then ground out and screw up all kinds of stuff. I would bet your being a servo motor error code. ( temp light flashing 6 times i think)

chsdaddy · Dec 1, 2008

I had not noticed any flashing lights but I wasn't looking for them either. I will check that first. Will the code be there until it is cleared, meaning if I start it anytime since the problem will it be there?

This is the first time I took the sled out, I bought it in September. Like I said earlier it ran like a top for about 45 min. It started craping out and I got stuck going up a hill. I shut it off got unstuck and it ran fine back to the truck, a short distance. I took off again and it took 2-3 mins and then started crapping out. Shut it off checked some stuff, ran fine 2 mins and crapped out. Did this for the remainder of the day. It feels like it is not getting fuel, but seems like an electrical problem if that makes sense. I also feel like it is something simple because it does run great, for 60 seconds at a time. Coolant level is good, and I could put my hand on the back radiator, it was warm but didn't seem overly hot, you could easily touch all of the coolant hoses.

Hopefully I can replicate the problem so I can start trouble shooting.

ccpowder · Dec 1, 2008

Sounds like a bad fuel pump. My '04 900 EFI did the same thing.

Rixster · Dec 1, 2008

You will only get the error when the sled does its thing. It does save the codes and you could go to your ac dealer and have them check your ecu history. If it sent a error code it will be in there. I can almost guarantee you have a worn through wire under your oil tank. That is EXACTLY what my sled was doing! I changed my stator my edu and my servo motor before I found the messed up wires. And that is what finally fixed it. I did end up frying my ECU before it was all said and done. I hope you caught it early enough that you didnt cook anything!
As for the ethanol wire, mine is black hooked to a gray/white. You want to unplug it if you are running ethanol.

chsdaddy · Dec 1, 2008

I am going to check all of the wires before I start throwing parts at it. Rixster, I hope you are rright. I am going to have to hoist up the back end in the barn to run it and try to get some time to work on it this week before dark. I looked at the hose that comes out of the bottom of the ecu I assume for the barametric prssure sensor and it was not plugged but did have some moisture in it.??? I have a fuel tank from an 03 MC 600 that has the same fuel pump in it (same part # for the pump only). The assembly isn't the same though. Does anyone know what the pressure should be? I can check that after work pretty easy without making too much noise.

m8inthemtns · Dec 1, 2008

The throttle safety switch and kill switch can be unplugged. This overides the function of the switch. Usually the plug is on the handle bars or below them. You will have to use the key to turn the engine on and off. A bad switch can be intermittent, and cause the engine to act boggy. If you have a owners manual you can read about it there.

Dobber1 · Dec 1, 2008

My money is on the "Power Valves". Take 'em out & clean them. Make sure cables are not broken (had ends come off), & see that cables are connected to the Servo Motor. Usually a cheap fix!

04 800 Mountain Cat Bogging

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