Bike stopped dead - crank sensor failed.

Got a technical query? Found another 0.02bhp? Ask/tell the world.

Moderators: Gromit, Paul, slparry

Pete.
Posts: 238
Joined: Thu Apr 02, 2015 7:16 pm

Bike stopped dead - crank sensor failed.

Postby Pete. » Fri Feb 05, 2021 6:39 pm

Heading in tor work this morning same as usual. A few minutes into my journey the engine mis-ired, faltered, picked up, cut out for a few moments, picked up again then just died.
Cranking made it pop and fart but not fire up. Eventually I gave up and got recovered home.

With the ignition on the fuel pump would continuously prime, over and over again at decreasing intervals over a few minutes until it stops priming. Whilst this is going on, every once in a while I got a feeble mis-fire from a cylinder - without touching a thing on the bike - until it settled down and just sat there doing nothng. Cranking the engine makes the pump run but the engine wouldn't start when cranked.

Shut the power off for 10 minutes, turn it back on and it the procedure repeated. Priming constantly but less and less often over a couple of minutes then nothing.

After a LOT of testing, checking, pulling stuff about I've concluded that the crank position sensor is dead. I shut off the ignition, gave it 10 mins, turned it on so thet it started it's messing about then un-plugged the hall effect sensor and it all stopped. Repeated several timeswith the sensor plugged in - messing about. Un-plugged - sits there behaving itself.

So, a new sensor is on the way, I'm reasonably certain that it will cure the fault. I bloody hope so anyway otherwise I've spent £160 on a part I didn't need and I'll still not have a working bike :)

User avatar
simon
Member
Posts: 872
Joined: Fri Sep 07, 2007 11:58 am
Location: Northumberland

Re: Bike stopped dead - crank sensor failed.

Postby simon » Fri Feb 05, 2021 10:10 pm

Hello Pete,
Appreciate the symptoms /diagnosis.. Will try and file just in case for future use..
Can anyone say why those Hall effect doohickies are that expensive? Are royalties due to Mr Hall?
Simon, now with a third
Yellow '98 R1100S
(..a bit more gimpy tho' [smilie=crutch.gif])

Pete.
Posts: 238
Joined: Thu Apr 02, 2015 7:16 pm

Re: Bike stopped dead - crank sensor failed.

Postby Pete. » Sat Feb 06, 2021 1:21 pm

Id on't think that the sensors themselves are that expensive, but they are potted into a plastic housing which is riveted onto a mount plate. The housing also has a magnet clipped to it. I bet if you could get those sensors out of the potting they would be a ten quid item.

One thing that bothers me is that the sensors are obviously a pair, one for each cylinder. You would have expected it to drop one cylinder given that it's highly unlikely that two sensors went out together. Makes me wonder if the fault is actually in the potted joint part way down the lead.

I might dissect the wiring to see if there is a break in it anywhere.

User avatar
nab 301
Member
Posts: 2374
Joined: Sat Dec 04, 2004 6:41 pm
Location: Dublin Ireland

Re: Bike stopped dead - crank sensor failed.

Postby nab 301 » Sat Feb 06, 2021 3:41 pm

It's often the wiring if you believe what you read on the internet... although so far I've never had to replace ....
_________________
Nigel

Keep smiling, it makes people wonder what you've been up to!
1999 R1100s (mandarin) '
2018 DL 250V Strom
2019 CB125F Honda.
MZ301 Saxon Fun ( currently retired)
'03 Bullet 65 project..

Pete.
Posts: 238
Joined: Thu Apr 02, 2015 7:16 pm

Re: Bike stopped dead - crank sensor failed.

Postby Pete. » Sun Feb 07, 2021 10:11 am

I've belled out the wiring on the sensor sub-loom, from the pins to where the wires enter the potting. No faults found in there. I don't think the problem is with the main loom because un-plugging the sensor stops the odd behaviour, plus once I pin-pointed the source of the fault I did pull the loom and connectors about a lot without it making any difference.

The replacement sensor is due on Tuesday. If fitting it cures the fault I'll take a die grinder to the old sensors and see if I can identify the encapsulated IC.

dave the german
Member
Posts: 3614
Joined: Tue Nov 01, 2005 4:35 am
Location: North East

Re: Bike stopped dead - crank sensor failed.

Postby dave the german » Sun Feb 07, 2021 10:14 am

nab 301 wrote:It's often the wiring if you believe what you read on the internet... although so far I've never had to replace ....


That's what I've heard too - IIRC the wiring breaks down when hot - sub standard wiring. Was it the Dan Cato (or something like that) fromGreece that were refurbished with better wire?
'15 R1200GS TE
'06 R1200S
'04 BCR
Yam SR 500 long term restoration
wanna win the lottery and ride my bike

Pete.
Posts: 238
Joined: Thu Apr 02, 2015 7:16 pm

Re: Bike stopped dead - crank sensor failed.

Postby Pete. » Thu Feb 11, 2021 10:47 pm

Just to wrap this up, new (pattern) part arrived today from Motorworks. Fitted this evening and the bike fired right up.

Glad to be back on two wheels.

Humbug
Member
Posts: 637
Joined: Wed Oct 28, 2015 6:06 pm
Location: Nottinghamshire

Re: Bike stopped dead - crank sensor failed.

Postby Humbug » Fri Feb 12, 2021 8:29 am

Great to see a post ending happily and with info that will help others :D
10 KTM RC8


Return to “Boxertech”

Who is online

Users browsing this forum: No registered users and 58 guests