It only works in the snow!

[Fender1515]

So out for a ride this afternoon, about a 2 hour route, set off up dhills, I live in Yorkshire, bike feels really smooth and sorted, 40 mins into ride and into Staleybridge, stop at lights, temp gauge climbs up two bars above normal fan cuts in as normal,  30 secs later engine cuts out, turns over but wont restart,not avin it. 

Umm, re-set TPS, check oil and water levels, all on their mark.

Roll bike onto pavement,  wait 15 mins for temp gauge to drop below normal,  bike starts and set off, not on the pavement!

3 miles and then temp traffic lights, borrocks, same outcome.

Wait 15 mins, bike starts, out onto open road 30 mins ride home goes without a hitch.

So, home, check visible connections, check battery voltage, all checks out OK

Hence conclusion, bike will only run in the snow!

Will be booking tbike into menders for diags check, this fault finding is above my paygrade.

 

Bike BMW K1200s, 19 years old, 30k on the clock, only clocked up 2.5k miles since full service

Any of you folks got any words of wisdom?

[Fiddlesticks]

Do bikes have sticky thermostats like cars do? Just a thought.

[Bender]

Does it have twin rads and fans, are both running, are the radiators clear IE the fins, not clogged up with 20yrs of flies  

[Fender1515]

7 hours ago, Fiddlesticks said:

Do bikes have sticky thermostats like cars do? Just a thought.

Possibly, but as mentioned, when running on the open road, the temp gauge stays at normal and the fan only cuts in when at standstill, temp rises as normal, then engine cuts out at idle,  so not sure that sound like cause. 

[Fender1515]

7 hours ago, Bender said:

Does it have twin rads and fans, are both running, are the radiators clear IE the fins, not clogged up with 20yrs of flies  

Only a single rad, and was replaced for new in 2016, I house the rad out as part of annual maintenance, these bikes are prone to rad gunking up. could be contaminated fuel, going back to basics, the only change since previous rideout which was fine, was fill tank BP Ultimate, bike like 98 fuel. 

[Mississippi Bullfrog]

Sounds like a dud crank position sensor to me. They are basically just an electronic magnet. Eventually you get a crack in the winding which opens up when it gets hot. As soon as it cools down again you're good to go. 

 

A mate had the same on his Guzzi. He'd had in a workshop for months and they couldn't find the problem. They even replaced the ecu at enormous cost. He then found out that his Guzzi uses an ecu out of some old Peugeot, you just swap the chip over. But having spent hundreds on it he then found it was a 30 quid crank sensor that was the problem. 

[Fender1515]

1 minute ago, Mississippi Bullfrog said:

Sounds like a dud crank position sensor to me. They are basically just an electronic magnet. Eventually you get a crack in the winding which opens up when it gets hot. As soon as it cools down again you're good to go. 

 

A mate had the same on his Guzzi. He'd had in a workshop for months and they couldn't find the problem. They even replaced the ecu at enormous cost. He then found out that his Guzzi uses an ecu out of some old Peugeot, you just swap the chip over. But having spent hundreds on it he then found it was a 30 quid crank sensor that was the problem. 

Thanks, interesting idea, is it probable a faulty sensor would cause engine cutting out only when engine hot and at idle, and the fault clears when engine cools down and bike runs OK when on open road?

[Mississippi Bullfrog]

22 minutes ago, Fender1515 said:

Thanks, interesting idea, is it probable a faulty sensor would cause engine cutting out only when engine hot and at idle, and the fault clears when engine cools down and bike runs OK when on open road?

I've seen faulty crank sensors do that. It's the heat that does it. Usually leave them 10 - 15 minutes and they fire up again. It won't repeat until the engine gets hotter such as at idle. 

[Fender1515]

5 minutes ago, Mississippi Bullfrog said:

I've seen faulty crank sensors do that. It's the heat that does it. Usually leave them 10 - 15 minutes and they fire up again. It won't repeat until the engine gets hotter such as at idle. 

OK, thanks, I will do some more research and see about sourcing replacement sensor. Cheers 

[Fender1515]

On 10/05/2024 at 07:54, Mississippi Bullfrog said:

I've seen faulty crank sensors do that. It's the heat that does it. Usually leave them 10 - 15 minutes and they fire up again. It won't repeat until the engine gets hotter such as at idle. 

I have finally  freed up some time to get spanners out and and try and sort out my engine hot cut when at idle issue, found my meter and checked for power drain when fans cut in, nope, did an eyeball check on wiring harness, nothing obvious dangling. Next check out crank case sensor,  as per the thoughts of MB, easy out, visual check, senor a bit tarnished, cleaned,  but no obvious failure in the casing, followed wiring up to the connector,  that'll be it, connector held to frame by a cable tie,  the connector is half apart, very excited, pushed them back together until the click, started bike, gets hot fan cuts in, temp drops fan cuts out,  gets hot again, and doesnt cut out as was the problem,  leave running for 5 mins, and SORTED. 

On with the gear, off we go, two hours blatting around the Peaks  sweet as a nut, biggest grin, you can get to feel very smug, when you see it say it sort it!

Thank you for pointing me in the right direction that man.

 

[Phil1]

I too would suspect something electrical related. 

 

Bikes/cars don't generally turn off at all even when overheating (unless they seize). They usually have some form of restricted performance mode and low coolant/ overheating warnings though but I've never known them shut themselves off as that would be dangerous. 

[Mississippi Bullfrog]

8 hours ago, Fender1515 said:

I have finally  freed up some time to get spanners out and and try and sort out my engine hot cut when at idle issue, found my meter and checked for power drain when fans cut in, nope, did an eyeball check on wiring harness, nothing obvious dangling. Next check out crank case sensor,  as per the thoughts of MB, easy out, visual check, senor a bit tarnished, cleaned,  but no obvious failure in the casing, followed wiring up to the connector,  that'll be it, connector held to frame by a cable tie,  the connector is half apart, very excited, pushed them back together until the click, started bike, gets hot fan cuts in, temp drops fan cuts out,  gets hot again, and doesnt cut out as was the problem,  leave running for 5 mins, and SORTED. 

On with the gear, off we go, two hours blatting around the Peaks  sweet as a nut, biggest grin, you can get to feel very smug, when you see it say it sort it!

Thank you for pointing me in the right direction that man.

 

Occasionally my presence on this mortal coil serves some useful purpose. Glad it's sorted.