Arctic Cat 2008 M1000 dies when you hit the throttle

[Barhoffrp]

Hi all, first post

bought my first ever sled last week, 2008 M1000 efi. 1300 miles. I’m new to sleds but it appears totally stock.

test ride consisted of a couple WOT pulls in a field,no issues there.

1st ride after purchase I went to a local trail. Sled started bogging noticeably shortly after warm up at all different RPMs. Limped it back and brought it into the garage.

Did a few diagnostics and test rides in the field by my place. Bog/hesitation has gotten worse.

so, here are my symptoms
-Sled starts great
-after allowing it 4-5 minutes to idle and come up to temp I hop on and go for a ride, 1st few minutes go ok
-sled starts bogging to the point of coming to a dead stop and barely running. sled will sputter and die if I give it throttle at this point.
-starts right back up, idles great
-I start feathering the throttle and can usually get it to slowly build some rpms
-finally builds up throttle and zoom! Off we go, sled runs awesome for 20ft to 100 yards, starts bogging again, process repeats.

It’s running like a carbed sled with dirty carbs.

here’s a few things I’ve done so far
-compression test:124 and 125 psi in the cylinders. Pulled intake, 1 cylinder does have some light scoring. Nothing major and not enough(I don’t think) to cause my issues
-pulled and inspected plugs. They looked new and were probably changed right before I bought it.
-cleaned power valves. They were clean but I had them out so I cleaned them up
-unplugged TSS, TPS, and kill switch. Issue did not go away

just wondering if you folks have any ideas to throw at me. It’s seems to be running lean, I’m trying to determine if it’s part of the fuel system(injectors, fuel pump, smart valves) or perhaps on the electric side(stator, grounded wire).

this is my first sled. I’m not a mechanic by any means but do most of the wrenching on my trucks and heavy equipment at work. My apologies if I seem clueless(I am)

 

[Bengalfan]

There is a lot of good people on here to help with answers. I don`t have a lot of wrenching experiene but did have an issue with my 2017 Mountain Cat that sounds similar. Have you checked the wiring harness. Sounds possible the sled heating up and harness may be grounding out against the frame. probably right side of the sled where it lays next to the motor

 

[Barhoffrp]

There is a lot of good people on here to help with answers. I don`t have a lot of wrenching experiene but did have an issue with my 2017 Mountain Cat that sounds similar. Have you checked the wiring harness. Sounds possible the sled heating up and harness may be grounding out against the frame. probably right side of the sled where it lays next to the motor

Appreciate the response, I have not yet traced wires looking for shorts. Your not the first to have had that problem so I realize that could be causing my issue. Currently dealing with the fuel side of things, I’m going to try and go through that whole system and verify everything works. If I don't find my issue I’ll move on to electrical and do as you mentioned

 

[Over budget]

Appreciate the response, I have not yet traced wires looking for shorts. Your not the first to have had that problem so I realize that could be causing my issue. Currently dealing with the fuel side of things, I’m going to try and go through that whole system and verify everything works. If I don't find my issue I’ll move on to electrical and do as you mentioned

Maybe Fuel fitter or fuel pump. I had one of those sleds and did loose a fuel pump once but it wouldn’t run at all she was dead on the mountain.

 

[Barhoffrp]

Maybe Fuel fitter or fuel pump. I had one of those sleds and did loose a fuel pump once but it wouldn’t run at all she was dead on the mountain.

It is acting like It’s not getting enough fuel. Currently have the injectors out and cleaning/testing them. Thought about just replacing them but at $400+ a piece from Cat I thought I’d try and see if the originals are ok to keep using. While I have the sled torn down this far I thought I’d better check the reeds(much more involved than I had anticipated) but as soon as reeds/injectors are put back together I’m going to move up to the fuel pump and smart valves(which is basically the fuel filter on this sled, from what I understand) and start working on those. Planning on cleaning smart valves and installing a fuel pressure gauge so I can monitor my fuel pump. Thanks for the response.

 

[Perk]

Sounds exactly like a fuel pump issue a buddy of mine had a few years back

 

[MT Backcountry]

I would replace the fuel pump first, I've been through 2 pumps in 10 years. The fuel now a day's is poor to say the least. Yes even the ethanol free fuel is not what it used to be. Walbro fuel pumps are only about $110 on Ebay.

 

[Old & slow]

It is acting like It’s not getting enough fuel. Currently have the injectors out and cleaning/testing them. Thought about just replacing them but at $400+ a piece from Cat I thought I’d try and see if the originals are ok to keep using. While I have the sled torn down this far I thought I’d better check the reeds(much more involved than I had anticipated) but as soon as reeds/injectors are put back together I’m going to move up to the fuel pump and smart valves(which is basically the fuel filter on this sled, from what I understand) and start working on those. Planning on cleaning smart valves and installing a fuel pressure gauge so I can monitor my fuel pump. Thanks for the response.

Check the smart valves in the fuel tank and make sure the vent is clear for the fuel tank. Check pressure of fuel pump, replace if it is out of spec. Seafoam is your friend also. The sled wont run right if at all with the TPS unplugged.
Edit I didn't read the whole post sorry for the repeat

 

[HIDY]

Tss

 

[Bengalfan]

Any update on this... Checking the wiring harness is free and pretty easy
Right in the belly of the engine compartment mine had the covering burned in spots and melted at least 1 wire insulation where it was grounding out. Just had to roll the harnes around to see it.

 

[Barhoffrp]

Update:
Busy 10 days at my job so work on the sled came to a standstill, but I had a couple hours this weekend so I tore back into it.

Took the throttle bodies out cause I wanted to check the reeds, I had heard that bad/chipped reeds could cause similar issues. (Side note: the AC engineers get a D- from me on airbox/throttle body design. That was a bear of a job for a first timer. Next time will go quicker but still not my favorite job ever). Reeds looked/felt great so I reinstalled them.

Now that I’ve verified reeds are good, I’m going to clean smart valves and install a fuel pressure gauge to monitor my fuel pump. I’ll update after those have been done.

 

[Barhoffrp]

The sled wont run right if at all with the TPS unplugged.

I did not know that. Everything I’ve read seems like people suggest unhooking it if you suspect it’s going bad cause it will run better. But this is my first sled so I have no idea what I’m talking about.

Any update on this... Checking the wiring harness is free and pretty easy
Right in the belly of the engine compartment mine had the covering burned in spots and melted at least 1 wire insulation where it was grounding out. Just had to roll the harnes around to see it.

I have not checked the wiring yet. Hoping to not have to but if I don’t find anything when I check the fuel side of things that’s where I’ll go next. A lot of posts have mentioned grounded wires and the resultant poor performance. The sled starts and idles very well-it literally idled for almost an hour at one point when I took it on a test ride. It bogged down in deep powder, lost all its momentum, then fired back up and I trenched clear down to the dirt. Spent close to an hour digging it out and left it running cause I needed the headlight to see what I was doing. Anyways, do you think it would still idle well if it had a shorted wire?

 

[Old & slow]

Lots of folks get the tss and tps confused. The tss can be disconnected and the sled will run, it is however a safety device so it is best to keep it in place and working and / or add a tether. I found all the pieces to install a magnetic AC one no splicing just plug and go.

 

[Bengalfan]

Yes pretty much what happend with mine. Maybe when it gets hotter insulation softens and allows intermitent contact. But yes I had the same thing start climbing a hill and would cut out, was mainly under load when it would happen so was hotter. Fresh out the gate in the morning would run great, then after warm up would be intermittant.

 

[spoon]

Could be a bad stator. Fuel pump winding could be getting weak which gets worse with heat.

 

[spoon]

Did you ever find your issue?

 

[CATSLEDMAN1]

just looked at two M1000 that some ski ers use to access the high country. both hard to start and began running poorly last spring .

When I checked into the hard start, lean running, on both sleds the rubber boots that the fuel injection unit slips in to mound to the engine, are cracked in various spots and sucking air, randomly. I can't believe they didn't burn these sleds down, but other wise engine checks out fine..............when you find it under 12 years of drool and crud. So 12 years on rubber like this...........pushing the envelope a little.

 

[Barhoffrp]

Did you ever find your issue?

Hey everyone, wanted to update. Sled sat most of the summer and I tore back into it last week with the fresh snow. I had picked up a non running 2005 M7 with a bad MCU. The fuel pump is the same on both sleds so I switched it out with the M7 pump. Problem is fixed. It still has a very small bog at low rpms but not noticeable and won’t cause issues riding. I’ll keep fine tuning to figure out the reason for the bog but as of now it’s rideable. Thanks everyone for the ideas and help

 

[jim]

Make sure you get a good, fresh tank of gas through it. I had the same sled and found that the low end hesitation/bog would clean-up when I ran 89 octane as opposed to 91 octane (I'm in idaho too). The 91 octane was too high for the compression and elevation and did not burn well down low. Also double check power valve synchro and cable tightness...just get both cables to have the same tension. I also found this sled to like more secondary pre-load tension to avoid sluggish or boggy low end.

 

[Old & slow]

Good point on the fuel these older M sleds actually require 87 octane on a stock sled.