Please Help Me Find 09 M8 Electrical Gremlins

[Brutus]

Just a thought..... You might check for a broken or cracked spider in the primary clutch. I've had this happen before and yield similar symptoms due to the primary grabbing the belt at idle rather than at normal engagement. see how the sled idles with no belt on or take cover off primary and inspect. Good luck

Bru

 

[Vern]

Had one M8 in our group start hard and then typically quit right after it would finally start (I think the tach was acting strange too)...we messed around with the wires going into the ECU and it would get better or worse depending on how you moved the wires. Replaced the main wiring harness and the sled has been good for the last two seasons.

Currently working on a M7 that is doing the same thing. Have had the main wiring harness on order but it has been on backorder for at least a month now. When we get it and if it helps I will report back.

id look into this before dropping coin on a stator, had a buddies m7 do the same you describe and after thinking we ruled everything out he bought a brand new stator only to throw it in and have no change. we had previously unplugged the harness from the ecu and it "looked" fine so we moved on. After the stator we unplugged it again and noticed it smelled like burning electrical, i started popping individual wires out of the plug and sure enough, two wires were black and nasty. Turns out they burned through the plastic in the connector and were shorting together. We had a trip coming so no time to order a harness so we cleaned up the wire pins shot some liquid electrical tape into the plastic connector put back together and it fired right up. That was a year ago, and its still running. He still needs to replace the harness, but I'm guessing he's gonna forget about it until it F's us over somewhere.

 

[kiliki]

Thanks Kiliki, it's been a while but, I remember unhooking a very small white connector inside the throttle block assembly as few years ago. I think you are right, it was the throttle safety switch. It sure as heck wasn't the throttle position sensor.

So, fuel pressure huh? The way the idle just slowly fades away getting quieter and quieter until the engine dies, that sure makes sense. Touching the throttle immediately kills it. I guess I will have to see what I have in my shop, I may have what I need or I will have to order some parts.

Any other fine ideas or thoughts?

when it drops like this look at the fuel pressure if it is under 42 the pump is done! it will run in the mid 30's but once you give it gas it will die.

 

[Frostbite]

Thanks for all the great ideas guys!

I don't have a fuel pressure tester yet so I may have to start with your other ideas. Thankfully, I documented what I checked last time. Hum...where to start....

 

[Frostbite]

My fuel pressure tester arrived but, I haven't tried it yet but, I did update the firmware on the Power Commander III USB to the latest version (from 2010). Of course the sled starts and runs just fine going in and out of the shop. It's going into the mountains miles away from civilization where it always acts up. I still think it may be a heat related issue?

 

[tchriste]

I too have an 09M8 that has the same issue, however I have found a way to reduce the effects. I see you are running a PC111 so you should be able to add fuel at 0 throttle below idle (500, 750, 1000, 1250 RPM ranges), I have found by adding fuel in this area the sled will start without issue however it takes a bit of work for the engine to respond to throttle. I have found that when this happens the AFR is usually in the 20-30:1 range and the engine is very lean. I find with the added fuel I can start the engine then flip the throttle and activate the TSS a couple of times the AFR will return to normal. I run a PCV, however I had the lean start issue right from the beginning when I bought the sled....it's more noticeable with the 925.
I also note you are running a tether, is it the old style with a rubber plug one presses on? If so maybe try a small screw in the end of the rubber plug that pushes the switch in on the tether. I've had to do this when my tether was acting up a couple of years ago....I'm in the process of replacement.
It sounds to me like you've checked everything, I understand your battle.

 

[Frostbite]

TChristie, how much fuel did you add at each RPM?

I may want to try this on my 2015 M8000 too, it also has hard starting issues.

 

[tchriste]

about 20%

 

[Hardass]

Is this sled modded out turbo ect?

 

[Frostbite]

Just to update this thread: I sold my 09 M8 to a buddy and he hasn't had one problem with it not starting. I think the update of the firmware on the PCIII I did before I sold it may have remedied the issue.