backfired now wont start

[Marmot MB]

Hi all, I am really hoping someone can help.

2008 Cat M8 162 track, 974 km, electric reverse, fox shocks, mbrp can, speedo is malfunctioned, the digital display only shows ododmeter and two buttons don't do anything ( have read that is common on 08 due to crappy factory seals)

I have owned this sled for a few weeks and have started it about 10 times to show to friends, take it for one ride. Always it started on second or third pull

Friday I started the sled the load it, -20 something out, stored in garage unheated. as usual it started on third pull. sat and idle albeit a bit bobbly but it was cold out. about 2 minutes later it bobbled a few times then backfired then quit.

Now I knew it was low on gas, but didn't realize how low, I realized it was out of gas by the fuel gauge. so I went and got new fuel and filled it. then proceeded to pull and pull and pull no fire.

now I am a great motorcycle mechanic but now zero about sleds, so thinking it was fuel injected I did what I would do with a car, put thorttle down and don't move it.

so I used a piece of string tied the thorttle wide open, thinking I had run the fuel lines dry and needed to get fuel through. well after about 8 pulls BANG a huge back fire.... okay maybe not a great idea, too the string off.

I then pulled about 100 times no fire at all, not even trying.

So I pulled a plug found it wet and black.... thinking plugs may be fouled I changed them, used a lighter to ignite any gas in cylinder heads, sure enough whoosh a pop of flame then burned itself out. then left it open for about 10 minutes to air out.

checked gap on new plugs and installed brand new.

put exhaust back on and tried to fire. first pull it actually seemed liked it might, but no.... every once in about 10 pulls the cord pulled easier and seemed like it tried a bit but still no.

I even disconnected the breather hose and dribbled a little bit of gas in there for the air input, thinking back a few ignorant bikes and lawn mowers that wouldn't start. no go, not even a hint of turning over.

I am by myself and couldn't check spark on plugs, obviously this is a must do.

but any thoughts out there what it could be ?

I disconnected the tether as the previous owner made a weird mention if it won't start unplug these and plug these together....

obviously I am getting gas due to the amount of fuel that was present even after sitting a whole day in now heated garage.

I am really wishing I had electric start now, but that is another thread.

any help or things to check is really appreciated.

 

[Modman]

Hi all, I am really hoping someone can help.

2008 Cat M8 162 track, 974 km, electric reverse, fox shocks, mbrp can, speedo is malfunctioned, the digital display only shows ododmeter and two buttons don't do anything ( have read that is common on 08 due to crappy factory seals)

I have owned this sled for a few weeks and have started it about 10 times to show to friends, take it for one ride. Always it started on second or third pull

Friday I started the sled the load it, -20 something out, stored in garage unheated. as usual it started on third pull. sat and idle albeit a bit bobbly but it was cold out. about 2 minutes later it bobbled a few times then backfired then quit.

Now I knew it was low on gas, but didn't realize how low, I realized it was out of gas by the fuel gauge. so I went and got new fuel and filled it. then proceeded to pull and pull and pull no fire.

now I am a great motorcycle mechanic but now zero about sleds, so thinking it was fuel injected I did what I would do with a car, put thorttle down and don't move it.

so I used a piece of string tied the thorttle wide open, thinking I had run the fuel lines dry and needed to get fuel through. well after about 8 pulls BANG a huge back fire.... okay maybe not a great idea, too the string off.

I then pulled about 100 times no fire at all, not even trying.

So I pulled a plug found it wet and black.... thinking plugs may be fouled I changed them, used a lighter to ignite any gas in cylinder heads, sure enough whoosh a pop of flame then burned itself out. then left it open for about 10 minutes to air out.

checked gap on new plugs and installed brand new.

put exhaust back on and tried to fire. first pull it actually seemed liked it might, but no.... every once in about 10 pulls the cord pulled easier and seemed like it tried a bit but still no.

I even disconnected the breather hose and dribbled a little bit of gas in there for the air input, thinking back a few ignorant bikes and lawn mowers that wouldn't start. no go, not even a hint of turning over.

I am by myself and couldn't check spark on plugs, obviously this is a must do.

but any thoughts out there what it could be ?

I disconnected the tether as the previous owner made a weird mention if it won't start unplug these and plug these together....

obviously I am getting gas due to the amount of fuel that was present even after sitting a whole day in now heated garage.

I am really wishing I had electric start now, but that is another thread.

any help or things to check is really appreciated.

I really hope you had it on a sled stand when you tied the throttle WFO. If it ever lit up on you like that, it might just go full on and take off! Regardless, you gotta check the spark. Sounds like you are getting fuel, now you need to determine why its not igniting. Double check all things like key on (KISS principle), could be something like throttle safety switch when you tied the throttle open, maybe you mi-aligned it?

 

[McGrath]

Sounds like the bottom end is full of fuel. You might have to change plugs and give her another 20 pulls without touching the throttle. Hope your arm can take it!

 

[meatbag]

All good advice, you could also heat the plugs a bit before putting them in. Invite some friends over and just at some point in the conversation ask them to pull it a few times...Heh, heh, heh...Meyesssss....

 

[Puba]

Pull your plugs, flash your cylinders (use a lighter at the plug hole openings, light the lighter to burn off excess fuel), as Meatbag said heat your plugs, quickly install and try to start it. That's of course after you check to make sure you have spark.

 

[Marmot MB]

consenscus seems to be that the bottom end is fueled up, but how do I get it dried out ? one tech said keep taking plugs out dry them put in, put pipe on, pull three times, pull them again and again and again, there has to be a better way.

I can say that when I put the pipe on last time now there is dribble marks of black comming out of the joints to motor and pipe from the spring connections... it is gas as well, so obviously the motor is super flooded.

wondering if pulling the injectors out is worth it ?

it is in a heated garage right now, but.... I really don't want to remove the plugs and leave them out with a natural gas furnace burning for it to off gas the fuel fumes.

I did notice moving the sled around yesterday there was wet spot under it, it is fuel and black.... not sure where that is coming from. I suspect it is the fuel I dribbled into the air inlet a few times, most likely that air inlet has a drain hose to the belly pan, that fuel is coming out of the drain hose / belly pan perhaps, I jumped on and wiggled the sled side to side violently yesterday, and no more came out. perhaps it's all gone now.

dare I try a aerosol spray IE Fire start ? like for carbs ? into the air inlet ? obviously a little dab will do ya here.

 

[sledderdoc]

It is likely the valves were stuck open and it is severely flooded. You will need to pull the exhaust off pull the plugs and get the fuel out by pulling on it a bunch. replace plugs and start with exhaust off. will spray fuel all over when it starts fyi. Valves can freeze open in extreme cold.

 

[Marmot MB]

update:

Tried to start it by pulling cord 4 times. First pull almost seemed like it might start, next three.... dead as a door nail.

Removed the upper pipe, upon doing so, fuel dribbled out the end that fits to the muffler assembly, I woudl say maybe just shy of half a ounce of fluid.

removed the new plugs, soaking wet but clean.

put a lighter to the exhaust outlet, whoosh and burned for 30 - 45 seconds. put lighter to spark plug holes little whoosh again.

Turned kill switch and ignition off, put rag over the spark plug holes and pulled sorta slowly 4 times, Rag soaked, Lit off fuel again with lighter, put rag on, pulled four times sorta slow again, lit fuel off again.

dried off plugs, installed put pipe back on tried to start, same thing first pull like it wants to, but no go. three more pulls nothing dead.

Pulled top pipe, smoke comming out (can't test spark alone) this leads me to beleive there is some ignition source happening. pulled plugs wet again, lit off top end, whoosh 30 - 45 seconds of flame.

Obviously the bottom end is flooded I would say, there is no way there is that much fuel produced by 4 pulls from the injectors.

Now how the hell do I dry this thing out ? is there a way to kill the fuel supply when pulling ? Cat tech said you get fuel every time you pull regardless of key or ignition switch position. I am guessing remove injectors, put into bucket, then start pulling on this thing to drag up the fuel and step by step keep burning it off ?

Leaving it in hot garage for now wide open. This is getting to stupid town quickly.

 

[kawasakikx250]

I agree.pull the plugs and pull the motor over a bunch to pump the fuel out of the bottom end. First though check for spark.

 

[CatMan16]

You can take the fuel hose off of the end of the fuel rail before the injectors. Then put the hose in a bottle and see if it is still pumping fuel with switches off. It doesn't make sense that the fuel pump would work with the switches off. Make sure you shut off any pilot lights before you have a bunch of gas vapors in your garage.

 

[TylerG]

kill switch/key kill ignition, does not kill power to fuel pump.

 

[CatMan16]

kill switch/key kill ignition, does not kill power to fuel pump.

Learned something new today.
Would the injectors be opening at all to still be putting fuel in the motor?

 

[TylerG]

Learned something new today.
Would the injectors be opening at all to still be putting fuel in the motor?

likely, as when you pull it over even with the switch off I believe you can see a slight glow even in your cluster.

I've heard of guys flooding their M's before.

 

[Puba]

If you have spark try a hotter plug? Heat range maybe off.

 

[moyiesledhead]

While you're scratching your head trying to figure out how to dry it out.....pull the wiring plug on your ECU and have a look at it. A little corrosion in there will cause all kinds of problems. Spent a week trying to get my nephews M8 going last year with similar symptoms. Did this little trick and it fired right up.

 

[Marmot MB]

came in for a coffee was getting super frustrated. I pulled the plugs, burnt off fuel re installed plugs 8 times, each time it damn near fires on first pull, even tried heating plugs.

I did manage to confirm each spark plug lead is generating a spark. so I have spark.

tried tipping the sled on it's side each way and jiggling it trying to get fuel out of bottom end.

even set the exhaust port on fire with plugs installed and kept pulling cord with ign switch off trying to burn off excess from bottom end, that was fun, big balls of fire on each pull.

what I seriously need to do is stop the fuel delivery, so when I pull I am not introducing more fuel while trying to get fuel out of bottom end.

pretty stupid there is no fuel shut off, but I get the reason having fuel run dry on a pull start machine with a fuel pump is a nightmare waiting to happen.

question ? can You bump pull start a sled ? I don't see why it shouldn't, hook it up to be pulled and pull it down the street ? it should fire up NO ?

higher RPM is sure to slosh up the fuel from the bottom much faster, faster spark rate, pistons acting as air pump moving wet fueled air through ?

I am at the point thinking for some reason way more fuel is being introduced with each stroke than is supposed to. I have been doing only three pulls between each plug swap out, and when I pull the plugs they are soaked and when I ignite it it burns for 30 - 45 seconds out of exhaust port and 10 - 20 from plug holes.

at this point anyone know a good Cat mechanic I can take it too ?

 

[Puba]

I would say your ECU is the issue.

 

[moyiesledhead]

I repeat.....check your ECU wiring plug!!!!!! Just because you have fuel and spark doesn't mean it's the right quantity at the right time. The ECU controls all that. Drove us crazy last year till we found it!

Also, the easiest way to shut off fuel into the engine is to unplug your injectors.

 

[Marmot MB]

well I bought a compression tester, 125 PSI in each cylinder after 4 pulls.

I pulled all the ECU connectors and any other I could get to all are in 100% visual okay condition. Perhaps I can take it to Cat dealer have them check it ?

Some other input I have received is it may be the reeds. looking at things I am not sure if this can be done by taking off fuel rail, then carbs then the bolting to release the reed assembly ? I would have to seriously doubt motor removal is required to change reeds ?

I seriously suspect my stupid WFO throttle string theory followed by the Earth Shattering KABOOM likely damaged something. Others have said check bottom end, to be honest not really sure how to go about that, not really possible to do a full visual inspection with it tucked in there so tight, gave it a once over with flash light as best I could, exterior visual I see no signs. Have not removed the belly pan yet, that I suspect will expose much more.

So far, there is fuel, there is spark, I suspect compression okay at 125 PSI cold on 4 pulls, ECU connectors all 100%.

I am open to other idea's but at this point I am really ready to just take it in, I don't really want to chase this for three weeks, I have a trip planned with this sled for the 20th.

everyone's input is greatly appreciated ! Holy Mother sleds are nothing like motorcycles.

 

[ned]

Pinch off the fuel line with some needle nose vice grips and keep pulling until it starts.this will not hurt the pump and will stop fuel from entering the intake and flooding it more. When it starts just undo the vice grips