Cold start stalling

[Chris216]

Has anybody had issues with cold start up stalling? With cooler weather last fall and today, my 1250 has been stalling on start up and takes some coaxing to get started. I did a search but couldn't find anything. I've been wondering if it has anything to do with the ambient air temp sensor and the fact that I keep the bike in a heated garage. I let the bike sit outside for about 20 mins before starting today, but still had issues. TIA

Chris

[Grumpy Goat]

I can't believe that I did some searches for starting issues and came up empty especially since my bike has had these issues in the past. Maybe I never mentioned them on this Forum Community.

Anyway, with my bike it is not the cold start that is the problem ... it's starting in the summertime, and others have reported this issue as well. What happens in my case is that the engine requires two pushes on the starter button before it starts, and many times the start on the second try is almost "lazy" but then it does not cut out. In the winter time I just have to look at the bike crossways and it starts! The colder the better it seems. Others who have had this problem (and I) guess that it is the summer blend of gasoline that we get that causes the problem. Makes sense as the winter blend has a higher Reid vapour pressure which makes for easier ignition, and my 1200 seems to be tuned better to the winter blend. The Yamaha does not care and starts the same throughout the year.

Sounds like your bike is starting and then stalling, as opposed to never catching on the first press of the starter button. Some sort of fuel starvation issue perhaps. How long have you had the bike, i.e. is this the first winter its being used? Does it happen with different grades of gas? I take it that the bike has been serviced regularly and all the usual suspects (plugs, air filter etc.) are in good order ...? These RSes are pretty solid when it comes to the engine so something must be going on that may not be typical ...

[Lee]

I have not heard of other 1250s starting then stalling.
Does your warranty run out soon?
I would get to the shop and have it checked.

[Chris216]

GG, the bike is a 2020 1250 with 7500 mi, I purchased it new in Feb 2020. Yes the bike starts right up and then stalls and takes some playing around with the throttle to keep it running. Bike has a fresh battery and lives on a battery tender in the winter. No codes on GS911. Never had this problem before last fall (thought the new battery would cure it, but no).
Lee, warranty ran out 6 days ago  , plus nearest dealer is 300 miles away...
Thanks for the replies
Chris

[Grumpy Goat]

GG, the bike is a 2020 1250 with 7500 mi, I purchased it new in Feb 2020. Yes the bike starts right up and then stalls and takes some playing around with the throttle to keep it running. Bike has a fresh battery and lives on a battery tender in the winter. No codes on GS911. Never had this problem before last fall (thought the new battery would cure it, but no).
Lee, warranty ran out 6 days ago  , plus nearest dealer is 300 miles away...
Thanks for the replies
Chris

Chris - thanks for the additional clarifying info. Sounds like it needs some sort of tune up of the fueling and/or emissions system. Battery would not alleviate such a problem, but plugs might and that is the easiest thing to check and cheapest to replace. Even if that doesn't cure it you still have a second set.

Do you periodically use fuel system cleaner like this? I do (when I remember) and I believe that it keeps the crud at bay (I say "believe" because I personally have no specific experience either way to say they work or don't work). That is another cheap thing to try. To reduce the time for solving this issue, if I were you, I'd do this even before the plugs (which should still be OK at 7500 miles).

Also, try different gas - I once filled up the tank for my Yamaha - from an Exxon station no less!! - and it ran like sh*t from the get go. Next fill up it was fine, as have all the fill-ups from that station (one of my regulars). I also bought gas for other vehicles from no-name pumps and had similar sh*t running experiences. So, I only buy so-called Top Tier gas (usually from Exxon) for my vehicles - all of them. The RS (at least mine) is *very tolerant* of what you put in it, and I am sure it would burn kerosene if you put it in.   I have only used mid-grade in my bike (as I refuse to use Premium on a regular basis - I am too cheap) and occasionally when on a long trip I will use Regular, and the RS does not complain or run any differently.

If none of these work then you may want to relent and bring it to the dealer for more intrusive troubleshooting using proper diagnostic equipment. These bikes have lots of systems and electronics to deal with emissions requirements and it could be that something undetectable to the customer is slightly off.

Warranty should not make any difference if it is tuning issue - you should still have to pay for the work done.

[Chris216]

GG, thanks, I haven't run a fuel system cleaner (I use Berrymans chem tool B12 in my other vehicles) thru the 1250 yet, I'll give that a try. My local station typically (no guarantees LOL) has the best fuel in the area, non ethanol premium 91 oct. But I'll have to give that a try. Thing is that once the first cold  start is done it runs fine for the rest of the day. I'll take a look at the plugs and see what they look like.
Chris

[Lee]

Thing is that once the first cold  start is done it runs fine for the rest of the day.
Chris

I guess that rules out a tank of bad gas. I'm guessing you've run a couple tanks of gas since you first noticed the problem??
I was wondering about a bad coil but the bike would run poorly running down the road.
Same thing with a mouse setting up home in the air box.

[Grumpy Goat]

... Thing is that once the first cold  start is done it runs fine for the rest of the day. I'll take a look at the plugs and see what they look like.

I agree with Lee that based on the "running fine for the rest of the day" it is probably not bad gas. Maybe a faulty choking sequence since it appears to be only a starting event, and is unlike the starting event I experience as mentioned.

I'd still check the plugs (free) and run the cleaner through it (cheaper than the trip to the dealer).

[Chris216]

A buddy of mine suggested trying to start it in the garage when the ambient temp is the same as the IAT sensor is reading. I'll give that a go in the morning and let you know how it goes.
Chris

[Grumpy Goat]

A buddy of mine suggested trying to start it in the garage when the ambient temp is the same as the IAT sensor is reading. I'll give that a go in the morning and let you know how it goes.
Chris

Can't hurt but I don't think that is a solution. Once the bike starts it should continue easily if slowly until warmed up. It's the starting that is the hardest part. But let us know.

[Chris216]

OK, went out to the garage this morning and with everything (IAT sensor & intake air) at the same temp, one press of the starter and it fired right up and high idled just as it should. I'm going to have to repeat this a couple more times to verify. But you really only get one "cold" start a day, and having to clear my 65 degree garage of ex fumes with 30 degree air...  I'll report back after a couple of days and test starts. I'm really thinking this has to do with the IAT sensor being warm and the actual intake air being 20-30 degrees cooler resulting in improper fueling.
Lee, I know what you mean on the mouse nest in the airbox. When I moved out here from Calif a mouse family moved into the airbox of my VTR and filled it with moving blanked scraps. I didn't discover it until the next time I cleaned the air cleaner. The mouse family must have had an interesting ride the first time I rode it!
Chris

[Grumpy Goat]

OK, went out to the garage this morning and with everything (IAT sensor & intake air) at the same temp, one press of the starter and it fired right up and high idled just as it should. I'm going to have to repeat this a couple more times to verify. But you really only get one "cold" start a day, and having to clear my 65 degree garage of ex fumes with 30 degree air...  I'll report back after a couple of days and test starts. I'm really thinking this has to do with the IAT sensor being warm and the actual intake air being 20-30 degrees cooler resulting in improper fueling.

Good result so far. Yes, please do let us know how the repeat tests go.

But now have to ask - how cold is the outside air when you wheel the mike out of the warm garage and leave it in the cold for 20 minutes before starting?

A good control would be to let the bike not be in a heated environment (i.e. let it be cold) and then start it. Rather than leave the bike out longer than you usually do, you could turn off the heat in the garage so that it gets as cold as it would, and then push the bike outside and let it sit for the 20 minutes before starting. I'd want to know what the results are then. With that information I think we could properly infer a conclusion.

[Chris216]

Quick update, bike started right up again this morning. I want to try one more in garage startup tomorrow and then the next cold day we get I'll throw it outside first thing in the morning and let it cold soak for 4 or 5 hours and see how that does. Due to the placement of the IAT sensor (bottom of the air box, right above the engine) I suspect that is one of the last places to come to ambient temp.
Chris

[Grumpy Goat]

Quick update, bike started right up again this morning. I want to try one more in garage startup tomorrow and then the next cold day we get I'll throw it outside first thing in the morning and let it cold soak for 4 or 5 hours and see how that does. Due to the placement of the IAT sensor (bottom of the air box, right above the engine) I suspect that is one of the last places to come to ambient temp.
Chris

Sounds like a good plan and I agree with you on the placement of the IAT sensor and the likely effect on its efficacy.

[Chris216]

Quick update, we've had a warm week so I've had to wait for some colder weather, but at least I got ot get out on a nice Feburary ride  . Rolled the bike out of the 65 degree garage this morning and let it cold soak for 3 1/2 hours in 40 degree air. Lit right up, a little stumbly but still ran ok. I've got to think that the bike is running fine and that the stalling is a result of the air temp in the air box that the IAT sensor is seeing vs actual ambient air temp. Kind of a first world problem (but then again aren't all BMW problems?  ), so I'll just have to deal with it on cold mornings...
Chris

[Grumpy Goat]

Quick update, we've had a warm week so I've had to wait for some colder weather, but at least I got ot get out on a nice Feburary ride  . Rolled the bike out of the 65 degree garage this morning and let it cold soak for 3 1/2 hours in 40 degree air. Lit right up, a little stumbly but still ran ok. I've got to think that the bike is running fine and that the stalling is a result of the air temp in the air box that the IAT sensor is seeing vs actual ambient air temp. Kind of a first world problem (but then again aren't all BMW problems?  ), so I'll just have to deal with it on cold mornings...
Chris

Great conclusion to this saga, Chris. Thanks for remembering to circle back and close the loop - much appreciated. 

Looks like the sensor is not as quick-acting as we'd like and as a result the engine is not getting appropriately choked so that it starts right away.

Speaking of slow sensors - on my RS the ambient air sensor (that tells the dash how cold it is; located just under the headlights on centreline, and above the front fender) is slow and this means that when I leave for home after work, it takes a good 5 minutes or so before the temperature changes from whatever it was when I shut the bike off after coming to work. IOW, if the temperature was say 45 deg.F when I came to work, up to 5 minutes after leaving for home in say 60 deg.F, it would still be saying 45 deg.F, before it magically jumps to 60 deg.F. I bought a new sensor some years ago but have yet to install it since it has not irritated me enough. The Yamaha has no such issue. Sometimes (?) it is good to have two (?) different bikes from different manufacturers side by side to show up what is "normal" and what should be normal.

[Lee]

Seems strange you would need to let the bike sit for so long before starting.
Shops in the northern states are able to roll a bike out of a warm shop and start them outside in very cold temps.

[Chris216]

Lee, I can start the bike immediately on pulling it out of the garage if I play with the throttle some. It will start with just the "button" and then stall, requiring a second start procedure. Normally I can just hit the button and it will go directly to high idle. I think in my case the ECU is looking at the IAT temp (70 degrees) and coolant temp  (70 degrees), going to it's fueling maps and saying it needs "X" mixture for when it's 70 degrees. Where in reality the intake air is much colder resulting in a lean mixture and stalling until the IAT sensor reads the correct temp.
Chris

[Lee]

Lee, I can start the bike immediately on pulling it out of the garage if I play with the throttle some. It will start with just the "button" and then stall, requiring a second start procedure. Normally I can just hit the button and it will go directly to high idle. I think in my case the ECU is looking at the IAT temp (70 degrees) and coolant temp  (70 degrees), going to it's fueling maps and saying it needs "X" mixture for when it's 70 degrees. Where in reality the intake air is much colder resulting in a lean mixture and stalling until the IAT sensor reads the correct temp.
Chris