I have a 2010 F800ST that has recently (ever since the weather started getting warmer in the last 2-3 months) been giving me some low-RPM trouble.
First, it was problems taking off from a stop. I had to rev up to 2-3k, at least, to avoid stalling it. Just a few days ago, every time the RPM dropped (whether starting from 0 speed or during gear changes), the bike would hesitate as if it's going to stall before the revs pick up.
Per the extensive discussions on this forum about such issues, I have found that people usually suggest looking at:
- Idle actuator valve and/or the hoses from it
- Charcoal canister
- Fuel pump and possibly fuel controller (?)
Here what I've tried/checked so far:
1. Checked the battery - it's fine (battery tender shows more than 80% charged light when connected).
2. When taking off bodywork to check the idle actuator hoses (picture attached), I noticed that the coolant level in the overflow reservoir was lower than the min mark (I topped it off to close to max). The most recent case of RPM stuttering happened within 5 mins of starting the bike up (before the fan kicked on), so I'm assuming the coolant flow from the reservoir wouldn't have even started?
3. Checked idle actuator hoses by lightly pressing them near the bends (didn't seem cracked or overly soft). I didn't tinker with the charcoal canister circuit because I didn't have a replacement zip tie or the hose connectors required to bypass it.
4. Borrowed a wifi-based OBD tool (inexpensive one off of Amazon) from a friend to check for fault codes. Neither of us could get Motoscan to connect to it, but my friend used another app that he uses regularly with his car to check for them. It showed the idle RPM of my bike correctly and showed no fault codes. It does show fault codes when he connects it to his car.
5. Did the throttle reset cycle (5x twisting throttle from fully closed to fully open with the power on, etc.). Also tried revving the engine in neutral just after startup (i.e. not after full warmup/fan-on) - it revved up and went back to idle without any issues.
It's been at least 3-4 weeks since I rode the bike and maybe 1-2 months since I refueled, so could the charcoal canister could have dried out if it ever did get saturated (and therefore isn't the culprit)? Also, given there are no fault codes, does it mean the fuel pump/controller are OK? The previous owner said he had replaced it when the bike had trouble starting (I didn't ask when this happened). I also read conflicting reports (https://forums.bmwmoa.org/showthread.php?68499-Devilish-stalling-problem-2007-F800ST/page2) of whether or not fuel pump issues show fault codes. The engine does have that slow oil leak from up top (valve cover, I think), but there has never been an oil pressure light. I also checked the dipstick recently and the oil level is almost near max.
I'm just hoping to narrow down what the problem might be. Right now, the idle actuator hoses are about $55, the idle controller around $190, the fuel pump seems to be anywhere from $60-70 (non-OEM) to either $237 or $425, and God knows what other one-time use parts or unexpected extra parts I'll need to purchase as well. I definitely don't have the budget to test out all of them, and I'm starting to think about getting rid of the bike altogether. If you have any insights on how I can troubleshoot this issue, I would really appreciate them.
First, it was problems taking off from a stop. I had to rev up to 2-3k, at least, to avoid stalling it. Just a few days ago, every time the RPM dropped (whether starting from 0 speed or during gear changes), the bike would hesitate as if it's going to stall before the revs pick up.
Per the extensive discussions on this forum about such issues, I have found that people usually suggest looking at:
- Idle actuator valve and/or the hoses from it
- Charcoal canister
- Fuel pump and possibly fuel controller (?)
Here what I've tried/checked so far:
1. Checked the battery - it's fine (battery tender shows more than 80% charged light when connected).
2. When taking off bodywork to check the idle actuator hoses (picture attached), I noticed that the coolant level in the overflow reservoir was lower than the min mark (I topped it off to close to max). The most recent case of RPM stuttering happened within 5 mins of starting the bike up (before the fan kicked on), so I'm assuming the coolant flow from the reservoir wouldn't have even started?
3. Checked idle actuator hoses by lightly pressing them near the bends (didn't seem cracked or overly soft). I didn't tinker with the charcoal canister circuit because I didn't have a replacement zip tie or the hose connectors required to bypass it.
4. Borrowed a wifi-based OBD tool (inexpensive one off of Amazon) from a friend to check for fault codes. Neither of us could get Motoscan to connect to it, but my friend used another app that he uses regularly with his car to check for them. It showed the idle RPM of my bike correctly and showed no fault codes. It does show fault codes when he connects it to his car.
5. Did the throttle reset cycle (5x twisting throttle from fully closed to fully open with the power on, etc.). Also tried revving the engine in neutral just after startup (i.e. not after full warmup/fan-on) - it revved up and went back to idle without any issues.
It's been at least 3-4 weeks since I rode the bike and maybe 1-2 months since I refueled, so could the charcoal canister could have dried out if it ever did get saturated (and therefore isn't the culprit)? Also, given there are no fault codes, does it mean the fuel pump/controller are OK? The previous owner said he had replaced it when the bike had trouble starting (I didn't ask when this happened). I also read conflicting reports (https://forums.bmwmoa.org/showthread.php?68499-Devilish-stalling-problem-2007-F800ST/page2) of whether or not fuel pump issues show fault codes. The engine does have that slow oil leak from up top (valve cover, I think), but there has never been an oil pressure light. I also checked the dipstick recently and the oil level is almost near max.
I'm just hoping to narrow down what the problem might be. Right now, the idle actuator hoses are about $55, the idle controller around $190, the fuel pump seems to be anywhere from $60-70 (non-OEM) to either $237 or $425, and God knows what other one-time use parts or unexpected extra parts I'll need to purchase as well. I definitely don't have the budget to test out all of them, and I'm starting to think about getting rid of the bike altogether. If you have any insights on how I can troubleshoot this issue, I would really appreciate them.