BMW K bikes (Bricks)

You are not connected. Please login or register

View previous topic View next topic Go down  Message [Page 1 of 1]


1Back to top Go down   K100 Fuel Tank Connector Resistance Empty K100 Fuel Tank Connector Resistance Tue Aug 14, 2012 6:25 pm

mike d

avatar
Life time member
Life time member
Hi,

I am looking at a friends K100 which wouldn't start. The first problem was lots of water in the tank, which clogged the fuel filter, and as a result the fuel pump was intermittently working. At one point the bike would start every time, but it eventually died while I was balancing then throttle bodies

I had the pump in and out a few times, but it decided to pack up altogether, even when trying to apply 12v and earth directly to the disconnected pump.

O.k so I got a second hand one which runs fine externally, but now won't run off the starter, or even when 12v is applied direct to fuse 6. I can see 9.6v at the tank connector, and on the pump +ve connection, but it doesn't spin up.

I measured the resistance between the (green/white) male pump input wire and the disconnected +ve from the pump and got 5.6M ohm, surely this isn't correct.

Can someone perform a similar measurement and confirm the reading. I would have thought it to be nearer to zero ohms.

At the moment the battery is on a battery tender to give it a boost, as I was wondering if the low voltage would be the culprit. I suspect a bad connection in the tank where the fuel level sensor is fitted.

Mike

    

sidecar paul

sidecar paul
Life time member
Life time member
Hi Mike,

If it's the pump coil resistance you're looking for, my spare reads 64 ohms.

Paul.


__________________________________________________
'84 K100RS (0014643) (owned since '85), 86 K100RS (0018891) with Martello sidecar (built as an outfit in '88),
'51 Vincent (since '67),'72 Montesa Cota (from new), '87 Honda RS125R NF4 (bought 2015) 
....No CARS never ever!
    

charlie99

charlie99
VIP
VIP
hi mike

that fuel pump connector is a known issue , many of us have found the socket side of the connection to either be corroded or the female parts-sockets to be slightly expanded and not making good contact .

a good cleanup of both the pin and socket is appropriate .

i have also found a slight squeeze of each of the socket sections maybe required to restore good conductivity .

i would have thought that 9.6 volts on the pump should have been enough to start the thing up ...but maybe you are measuring the earth outside the tank to the positive inside the tank ? could there be loss on the earthy side of the connector ?

good luck


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%OK100 Fuel Tank Connector Resistance Au-log10

'86 k100 rs.. #######..  "Fred " (f(rame) red ) ( Fredrick leichtundschnell ) - -
bits and pieces from many kind friends across the k100 world ...with many thanks ..
    

mike d

avatar
Life time member
Life time member
O.k. Update time.

Went to the bike this morning, took the battery tender off (showing full charge).

Decided to put a jumper wire from fuse 6 to the +ve terminal of the pump (outside of the tank, and with fuel pipe removed). At this point the +ve, brown pump wire wire was disconnected from the pump, and the -ve was connected to the pump. The under tank connector was connected (to give me the earth return, which by the way measured 1.2 ohm between the male pin and the pump end black wire connector).

Turned the bike on press the starter (10.9v measured at fuse 6) and the pump ran fine. Reconnected the pump +ve lead, disconnected the flying lead from fuse 6, press the starter, again all fine.

Reassembled the pump back into the tank, and the bike fired up after a few seconds. Fuel returning to tank, and all is o.k. Very Happy

P.S my old non running fuel pump measured 9.4 ohm.

The friend should be a happy bunny when he gets back from touring on his K1200. Well I say on his K1200, but he managed to get a failed bearing in the rear bevel drive while in the Pyrenees, and is continuing the journey by car! (Most of the The French take August off for their holidays).

The same drive failed on him last year while in Germany, and was repaired out there. I did ask whether the preload shimming was measured, but he didn't know. So it looks like I have a K1200 rear drive rebuild coming up!

Would still like to know what resistance measurement anyone else gets when measuring from the male (green white wire under tank terminal to the (disconnected) brown +ve wire of the pump.

Mike


    

mike d

avatar
Life time member
Life time member
Hi,

Just to pass on a reason why you need to check and clean out you fuel tank.

Out of curiosity I stripped the old pump down and the central shaft was seized on to the the core of the commutator section. It was near the lowest part of the shaft, i.e. the portion that would be nearest the gauze filter, and thus any low lying water. Not much, but enough corrosion to prevent the pump from rotating.

Mike

    

charlie99

charlie99
VIP
VIP
mike if you do a little investigation you will find that the roller cell used in our fuel pumps is suceptable to any matter above about 8 micron ......to put that into perspective thats the same as super fine "4 f "sheeps wool or about 2-5 times thinner than a human hair . the basket filter is suposed to filter out such particulate matter ...but water does get in ...corrosion and such (usually rubber from the basket and pump retainer is far bigger than this in size) and can really affect the mechanism...

unfortunatly we forget that rubber breaks down over time and with all the additives and chemical changes that develop durring evaporation , retension of water and such ,,,the fuel ends up like varnish ...just waiting for someone to try and push it through a crushing mill ...something has to give ....and it usually ends up siezing the roller cell assembly .

i have opted to try a different type of pump ....one that is a small turbine (later design and now current principles ) ...and far less susceptable to those miniscule tolerances .

just be aware that such things exist and that not always replacing same for same is always the best forward thinking when alternatives that work well exist .

i dont say its a winner idea ...but just more chance of it surviving life in the real world of grit, grime and old rubber systems ..

hope you enjoy the ride .. they are a great beast


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%OK100 Fuel Tank Connector Resistance Au-log10

'86 k100 rs.. #######..  "Fred " (f(rame) red ) ( Fredrick leichtundschnell ) - -
bits and pieces from many kind friends across the k100 world ...with many thanks ..
    

mike d

avatar
Life time member
Life time member
Hi Guys,

Update 2!

The bike played up again today, fuel pump not running off the starter button. Double checked and all was fine when 12 volts applied direct to the pump terminal (unlike the original pump).

Being checking through, the under tank 4 way plug was fine, so I decided to remove the float assembly panel, those screws were 'F' tight.

Assembly on the bench, and the first fault was a bad connection of the earth terminal (the one on the float terminal), but that was reading o.k. resistance wise so left it to check out the positive leg. From the male feed in the 4 way plug I got infinity ohm measurement to the +ve terminal, so stripped back the insulation and used a pin to pierce into the wire. Eventually had all the outer insulation peeled back right up to plastic, encapsulated plug mounted on the float panel.

I used a dremel to cut away the filler, until I could just see the bare sections of the 4 wires. Still no continuity between the inside terminal and as near as I could get the pin to the outer side connector (still on the wire).

Without trashing it completed the conclusion is that the small 4 way panel connector pin is knackered (the other three wires measure fine through to the inside).

I will ring Motorworks in the morning to see if they have another, working assembly.

I think that this was the root cause of the original pump giving up the ghost, as the owner of the bike just left it in his garage once the bike had failed to start up. The water left in the tank subsequently knackered the original pump.

Mike

    

charlie99

charlie99
VIP
VIP
good find mike ....

good luck !!!


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%OK100 Fuel Tank Connector Resistance Au-log10

'86 k100 rs.. #######..  "Fred " (f(rame) red ) ( Fredrick leichtundschnell ) - -
bits and pieces from many kind friends across the k100 world ...with many thanks ..
    

mike d

avatar
Life time member
Life time member
Final Update.

The ping pong ball float sensor and new o ring were ordered from Motorworks yesterday morning and arrived on my doorstep at 09.30 this morning.

I made up some new bolts for the fixing plate as I had only managed to get two out without resorting to mild violence Smile

The new assembly was wiggled into place, tank put on the bike, 5 litres of fresh fuel poured in and off she went. Running smoother than before, probably due to getting a decent voltage to the pump!

Just waiting for my morgan vaccum gauges to come back from a loan, and the throttle bodies will be balanced.

Last night, I met up with the friend who owns the bike, he is just back from his tour of Southern France on his K1200LT. We are waiting for the bike to get back to England so I can look at the suspected rear bevel failure.

Mike

    

10Back to top Go down   K100 Fuel Tank Connector Resistance Empty Re: K100 Fuel Tank Connector Resistance Wed Aug 22, 2012 10:08 am

charlie99

charlie99
VIP
VIP
great work mike ...cheers !


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%OK100 Fuel Tank Connector Resistance Au-log10

'86 k100 rs.. #######..  "Fred " (f(rame) red ) ( Fredrick leichtundschnell ) - -
bits and pieces from many kind friends across the k100 world ...with many thanks ..
    

View previous topic View next topic Back to top  Message [Page 1 of 1]

Permissions in this forum:
You cannot reply to topics in this forum