f800 stalling problem

[salome44]

BMW: I bought a used 2007 f800st two years ago from Hansens BMW in Medford (Phoenix) OR. Have had trouble with stalling ever since. Have spent well over $1000.00 at Hansens shop with no improvement. Had to other shops with no success. I've read maybe between 50 and 80 letters on forums from those suffering exactly the same problem. Can you not find a fix for this after years of the same problem. I love the bike otherwise! This is my 5th BMW since 1978 but I'm afraid will be my last if it is impossible (or even more expensive) to repair. Sincerely, Jim Millhollin

[ccramerusc]

My 08'ST had the stalling problem for about a year. I did a bunch of things to try to fix it, sometimes several things at a time, so I'm not sure what exactly fixed it, but it's been fine for a few years now. Perhaps if you could share what was done for the $1000 you spent, we could tell you what else to try.

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[Cheesy rider]

Have you tried a booster plug ?

[salome44]

My 08'ST had the stalling problem for about a year. I did a bunch of things to try to fix it, sometimes several things at a time, so I'm not sure what exactly fixed it, but it's been fine for a few years now. Perhaps if you could share what was done for the $1000 you spent, we could tell you what else to try.

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Sorry this took so long to respond. here goes: I have replaced the fuel pump and filter, added Techron fuel add., checked fuel tank for vacuum (none) , tested the idle air control valve, done the throttle/ignition reset. Dealer has :replaced idle actuator hose, replaced feed pipe, replaces fuel filter pressure O ring, checked fuel pressure( 42 lb.), replaced intake boots, replaces idle bypass hoses,s checked valve clearance, replaced coils and spark plugs, replaced air filter element, up dates computer software, and ran bike on dyno. for hours without it replicating my problem. Dealer Craig Hansen, Medford, OR has been great but can't find the problem. I took the bike out for a ride from the shop and it started stalling within the first hour. Someone suggested a "booster plug". don't know what that is. I'm about finished spending money on this bike, but I would love to solve this as I totally love the machine! Have been riding it this winter in 60 degree weather and it has not stalled once! Only happens on longer rides in warm to hot weather. Thanks for reading all this. J






,

[ccramerusc]

A booster plug essentially tricks the computer into thinking the air temp in the air box is very cold. That results in the engine running richer as if the engine was cold. It also significantly smoothes the idle and makes the bike much easier to ride very slowly (like in bumber to bumper traffic). I have one and can attest to most of the claims, however the computer seems to "learn" that something is wrong and adjusts. So everytime I have the battery cover off, I unplug it and run the engine, then plug it back up before closing it up. I've heard that an "accelerator module" does the same thing for half the price. Worth looking into.

As for the other stuff, it looks like lots of wasted money. You've confirmed that it's not fuel supply (pump, filter, pressure, etc). You've confirmed it's not spark (plugs, computer). So IMHO it must be idle circuit. You've replaced the vacuum hoses, so all that's left is the idle air control activator and throttle position sensor (to tell the computer to make the IAC activator to do its job when the throttle is closed). You stated that it was checked, but that doesn't tell the tale of an intermittent problem. The computers and testing tools can check that it responds appropriately, but all it takes is being off a fraction of an inch one time to cause a stall given how lean these bikes run at idle. Cleaning it would probably help, but I would consider replacing it. I replaced mine with a used one from eBay.

That's my guess and advice.

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[meteor88]

Nice Motorcycle, i ilke this style, happy can join here..

[Claudio_S]

BMW: I bought a used 2007 f800st two years ago from Hansens BMW in Medford (Phoenix) OR. Have had trouble with stalling ever since. Have spent well over $1000.00 at Hansens shop with no improvement. Had to other shops with no success. I've read maybe between 50 and 80 letters on forums from those suffering exactly the same problem. Can you not find a fix for this after years of the same problem. I love the bike otherwise! This is my 5th BMW since 1978 but I'm afraid will be my last if it is impossible (or even more expensive) to repair. Sincerely, Jim Millhollin

Hi Jay,

My wife and I have had 4 F800-twin machines between the two of us (2007 F800ST, 2010 F800GT, 2010 F650GS Twin, and new 2019 F800GT). We've only had the stalling issue on the F800ST.

If you are mechanically inclined, the community can help you solve your problem with a big investment of time and less money than you've spent.

In terms of your situation, I agree with Cramer, the idle air circuit seems and throttle position sensor are the remaining items that haven't been scrutinized yet. The "only stalls when hot/after & during a longer ride" could also implicate the fuel pump controller.

If you embark on a DIY journey, you'll benefit from something to read and clear fault codes ( a MotoScan or GS-911) which also allow you to calibrate a few key things like the idle air control actuator.