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Discussion Starter · #1 ·
Went out for a ride yesterday, got to around 30 miles, filled up with petrol, went onto a local pub, got back to the bike around an hour later and it wouldn't start, after a tow home I started on my tupperware party to try to work out whats gone wrong here's where I'm at:

1) cut off switch is fine as it cranks over with it on the "on" position and doesn't when its off

2) cant be side stand as it wouldn't crank over

3) I have a spark on the plugs but am a bit worried about fuel

4) Checked all the fuses for continuity

5) Checked for voltage on one of the injectors and it does go up to around .30v

6) fuel pump spins to begin with then stops, I assume this is normal?

The bike in the past has been hesitant to start when its hot, I normally have to blip the throttle to start it once its been running, I'm assuming that this could have been the begining of my problems.

I'm about to look at the crank pickups next, has anyone else come accross this?
 

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JonnyQ said:
6) fuel pump spins to begin with then stops, I assume this is normal?
Yes -- the pump runs long enough to pressurize the fuel rail, then shuts off.

Any chance the fuel filter has been replaced recently?
 

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JonnyQ said:
3) I have a spark on the plugs but am a bit worried about fuel
What is the basis for this worry? Have you checked the spark plugs and found them dry?
 

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Discussion Starter · #4 ·
Plugs aren't wet, no real fuel smells when she cranks over for a while even with one of the plugs out, I've read some articles regarding possible fuel lines leaking inside the tank, its just really strange for the bike to simply not start as it must have started at least 5 times on the short run, i.e stopped to meet up with another biker, stopped for petrol etc.

I did fill the tank right to the top about 8 miles before it broke down it was pretty low i.e. 50 miles left on the Bavarian Computer with the reserve light just comming on.

It hasn't had a fuel filter changed recently, I suppose it could have picked something up with the fuel left low but I'd expect it to splutter a bit or at least give a sign.

I had an 84 k100RS with no probs and a K1200RS no probs so I know the basics of the K engine but my 01 1200LT is the first to let me down on a run, the old K100 did have an output shaft seal on the pickups which leaked so I thought I'd look there on the 12 to see if oil might have fouled the pickups, as the more modern K might use the same pickups for the fuelling timing as well as the sparking but that's only my guess I could be barking up the wrong tree.

As I have the tank off I'll investigate the pump and internal lines first and go from there, probably wont get round to it until after work tomorrow.

Wish me luck
 

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Your notes further suggest to me that the in-tank hose has slipped off the fuel filter.

My thought process:

The lack of fuel at the cylinders suggests (obviously) no fuel delivery from the fuel rail. Few things can cause that -- primarily no delivery from the tank, or no flow through the injectors.

No delivery from the tank: the combination of fuel pump clearly receiving power + running + sudden onset = hose likely off fuel filter, not an electrical issue. Highly unlikely to be a clogged pump inlet -- the inlet strainer is too big to suddenly clog.

No flow through the injectors (other than no flow from tank): dead Motronic computer -- extraordinarily rare, highly unlikely; failed fuel pressure regulator, no way (when they fail, pressure goes high, not to zero); injectors not receivng signals, possible, but not likely (don't have my schematic with me to see whether there is a single point of failure for all 4 injectors, and would expect to see an intermittant failure from a separating connection or wiring short/break, rather than sudden failure).

So, I believe your tank check is a good idea -- also one of the easiest things to check first.

Good luck.
 

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Discussion Starter · #6 ·
'Tanks' for your tip mneblett at least taking the tank off will allow me to better route the sat-nav cables and change the airfilter, dont really want to take the plastics off too often!!

Typically the first sign of good weather in Wales (it normally just rains) the bike breaks down.....

I'll be draining my full tank tomorrow and having a peep, I think your right about the electrics as I did have a reading off a volt meater when I cranked it over from of of the injectors off the rail although it was very low at around .30v but I suppose all its doing is opening a jet.

I'll check in tomorrow with further findings.

Thanks again
 

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Jonny: +1 to Mark's advice.

Trying to measure voltage on injectors with a voltmeter will not work, the pulses are too brief for an indication on analog or digital meter.


All side-stand / clutch switch nonsense is eliminated when you try to crank in Neutral - you did already confirm this, anyway.

Slipped hose off the fuel filter is reasonably likely cause. Some riders reported seeing fuel whirling in the tank with such failure on bikes with a center filler. It may be hard to see it on an LT, but maybe with a mirror and a flash light (torch, that is), you may get a glimpse.

Good luck!
 

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Discussion Starter · #8 ·
Stupid pipe was no where near the filter, I dont know who serviced it last............ it had full fluids and filter when I bought it around 8 months ago.

Nevermind I'll get myself a new filter I may as well change it now anyway.

Thanks for all your help guys, p.s. should I replace the hoses and clips as they have those clips which you cant tighten on the hoses?
 

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JonnyQ said:
should I replace the hoses and clips as they have those clips which you cant tighten on the hoses?
How many miles on the bike? Unless a large number, should be no reason to change the hoses (unless you've seen visible signs of deterioration; cracks, etc.).

The hose clamps may be replaced with screw-type *IF* you use proper fuel injection line clamps -- ones with a smooth inner diameter surface -- the usual cheap clamps' thread slots can chew through the hose over time due to vibration from the pump.
 

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Discussion Starter · #10 ·
Thanks for your tips, it just felt a little easy to go back on and pass the nobly bit on the pipe, the bike has only done around 29k so not really high mileage, however the top hose does have a very severe bend when you put it on, it looks original but it does look almost as if the pipe could get flat in the middle and reduce fuel flow as it is quite short.

I'll wait for my new fuel filter, I may as well change my throttle cable as well as they seem very tight on the twistgrip.

I was hoping to have done all of this work in the winter.... nevermind.

Thanks again
 

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The OEM hose is a pre formed hose so there is no "kink" in the middle of the bend.
 

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Discussion Starter · #13 ·
Those fuel lines look good, trouble is I keep on opening other jobs on the bike, I've got the bike running now, and have also changed filters and plugs.

I now have three jobs which I fancy doing:

1) radiators have oxidised so I may take them off drain the fluid and give them a sand down and paint.

2) fork legs have bad paint, I fancy taking these off to give them a freshen up with some silver, I did read somewhere that they have oil which needs changing, is this true?

3) the dreaded brake fluid could do with changing and its probably a lot safer with the plastics off.

I'm not worried about the final drive or main oil as I did those about 6mths ago.

My little bit of garage tinkering time may well take up around a weeks worth of evenings at this rate!!

Anyone done a fork fluid change on one of these? and is it work it at 29k?

Thanks in advance
 

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JonnyQ said:
2) fork legs have bad paint, I fancy taking these off to give them a freshen up with some silver, I did read somewhere that they have oil which needs changing, is this true?
No.

The oil in the forks only provides lubrication of the sliding surfaces between the tubes and the legs -- there is no damping whatsoever (imagine two big fat concentric tubes, with nothing insde them). There is basically nothing in the tubes which would degrade the oil.

The only reason I would change the oil is if there was a leaking fork seal to be replaced, and even then I would only replace the oil because I already had the fork apart and wanted to ensure the correct amount is put back in the tube.
 

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Discussion Starter · #15 ·
Brilliant, thanks for that, I'll just drop them and freshen them up with paint.

Thanks for your tips. :)
 

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Discussion Starter · #20 ·
Excellent, I love this forum everyone is always so helpful.

This should keep me busy for a good few days.

Thanks again Mark :)
 
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