BMW K bikes (Bricks)

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daveyson

daveyson
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How to ride home when your fuel pump fails 01010


If your fuel pump fails, you're in an isolated area and you don't have a spare, simply connect a wire from the yellow - grey wire (earth to injectors) to the battery negative post,  and you can ride home. 

This provides constantly open injectors, which with the help of gravity fed fuel and vacuum from the pistons, is enough,  but not ideal,  to ride home. It is sometimes a little on the rich side which can be overcome by backing off the throttle. 

I have proved this today with a one and a half hour ride (45 minutes each way)  reaching speeds of 100 kmh (60 mph)

This was with a 2v brick. The pump is working, so I simulated a failed pump by disconnecting the fuel pump electrical plug.

It helps to keep the revs high.

If the pump were to suddenly start working again, that would result in a stall because of the constantly open injectors, so unplugging the fuel pump plug would be best with this temporary modification.



Last edited by daveyson on Sat Feb 29, 2020 2:48 am; edited 8 times in total (Reason for editing : Edit for photo.)


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11/1985 bmw k100rt (late model)  Vin. 0090567
    

charlie99

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amazing ...!!!!


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

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%OHow to ride home when your fuel pump fails 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 ..
    

RicK G

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@daveyson wrote:If your fuel pump fails, you're in an isolated area and you don't have a spare, simply connect a wire from the yellow - grey wire (earth to injectors) to the battery negative post,  and you can ride home. 

This provides constantly open injectors, which with the help of gravity fed fuel and vacuum from the pistons, is enough,  but not ideal,  to ride home. It is sometimes a little on the rich side which can be overcome by backing off the throttle. 

I have proved this today with a one and a half hour ride (45 minutes each way)  reaching speeds of 100 kmh (60 mph)

This was with a 2v brick. The pump is working, so I simulated a failed pump by disconnecting the fuel pump electrical plug.

It helps to keep the revs high.

I partially pulled back the rubber gaiter between the fuel injector unit plug and the wiring harness to gain easy access to the yellow /grey wire. If the pump were to suddenly start working again, that would result in a stall because of the constantly open injectors, so unplugging the fuel pump plug would be best with this temporary modification.
It can also cause the coils to overheat in the injectors which will cause you lots more grief and a new set of injectors.


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"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived."   Dalai Lama


Bikes 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki
    

4Back to top Go down   How to ride home when your fuel pump fails Empty Fuel pump failure on Sun Aug 04, 2019 11:27 pm

daveyson

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Good to know,  thanks,  I never thought about that. So I spose only worth the risk if you're really desperate. Are there other pitfalls with this modification?

Anyway, at least I have found out it's possible to survive a 45 minute ride.

I was actually wondering about the fuel temperature as there is no pump circulation for the fuel.


__________________________________________________
11/1985 bmw k100rt (late model)  Vin. 0090567
    

RicK G

RicK G
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If it had been summer and 40°C you would have fried the injectors. they only open for a matter of micro seconds and so don't get hot normally


__________________________________________________
"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived."   Dalai Lama


Bikes 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki
    

6Back to top Go down   How to ride home when your fuel pump fails Empty Fuel problem on Mon Aug 05, 2019 3:02 am

daveyson

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Beauty.  Thanks for your help with understanding this strange situation.


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11/1985 bmw k100rt (late model)  Vin. 0090567
    

ERasberg

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Great tip !!


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Present
1988 K100 RS SE - VIN# 0146971K100RS - 105,000 km
1998 R1200C
1971 R75/5

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1981 R65
    

92KK 84WW Olaf

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Well we see 45 but its those Fn degrees so its a good tip to know.

That should go up in a place along with Sidecar Pauls tip on non opening fuel caps and a few more things.


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1992 K100LT 0193214 Bertha Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red 578 bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 689 58,645 now 106,950 miles Deceased.
1983 K100RS 0011171 Fricka 606 Alaska Blue 29,495 miles Damn K Pox Its a Bat outta Hell Now 36,188  miles
    

MartinW

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A cheap AliExpress OEM copy pump is cheap insurance, I have one fitted to the bike and a new spare in the tail.
Regards Martin.


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K75s Hybrid
    

tinyspuds

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@MartinW wrote:A cheap AliExpress OEM copy pump is cheap insurance, I have one fitted to the bike and a new spare in the tail.
Regards Martin.
Hi Martin,
Do you have a link for that please?
Thanks, Stu


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1985 BMW K100RT + Hedingham HUB and LL’s. VIN 0028106. (Not blind to the irony of an April 1 production date).
1954 Royal Enfield 350 Bullet. Original.
    

MartinW

MartinW
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Stu go to this link https://www.aliexpress.com/ And type in BMW K100 fuel pump and you'll get multiple sites. I've been running one with no problems since July 2017. http://www.motobrick.com/index.php/topic,10054.msg86054.html#msg86054 It ran faultlessly on a 3 day 1400 Km trip in 40C + heat.
Regards Martin.


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K75s Hybrid
    

tinyspuds

tinyspuds
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@MartinW wrote:Stu go to this link https://www.aliexpress.com/ And type in BMW K100 fuel pump and you'll get multiple sites. I've been running one with no problems since July 2017. http://www.motobrick.com/index.php/topic,10054.msg86054.html#msg86054 It ran faultlessly on a 3 day 1400 Km trip in 40C + heat.
Regards Martin.
Cheers Martin


__________________________________________________
1985 BMW K100RT + Hedingham HUB and LL’s. VIN 0028106. (Not blind to the irony of an April 1 production date).
1954 Royal Enfield 350 Bullet. Original.
    

13Back to top Go down   How to ride home when your fuel pump fails Empty Fuel pump fail on Fri Feb 28, 2020 10:32 pm

daveyson

daveyson
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I still get a chuckle now,  thinking back on that day.  

That ride was to a mates place ( rides a kle500,  cheaper rego) This was one tall story that simply went too far to believe. He thought a fuel injected motorbike,  or a fuel injected anything, couldn't run with the fuel pump unplugged, and wouldn't believe it unless he saw it with his own eyes. He looked at the wiring, he followed the fuel lines from go to woe,  looking for a hidden pump... eventually... eventually... reluctantly... he conceded. The look on his face was priceless, he was shocked to the shit house. 

I, myself, felt like a stunned mullet, when I finally got this non running bike going by unplugging the fuel pump! I even hopped on it and rode around the block, as I was riding, I remember thinking "this is bull shit,  but it's true" I couldn't get the smirk off my face.

Somehow I fixed the problem, without ever finding the cause. A year or so later, I tried to reproduce the problem. With a bit of effort and help,  I found this way. 

The bike runs a bit rich like this, but feels pretty normal if the revs are kept high.  It's down on power though,  so the revs might drop if you're going up a steep hill,  so then you have to down change well in advance, to keep the revs high,  a bit like driving a truck. 

OK, now for the "over my head" bit. 

The book says bricks run on a fuel pressure of 36psi. Atmospheric pressure is 14.7psi. Engine vacuum of 20 inches of mercury, let's say that converts to 10psi. (don't know if this applies to bricks,  or bikes) So let's say 25psi, that's enough. Especially considering the injectors are constantly open instead of momentarily, which makes it more than enough.


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11/1985 bmw k100rt (late model)  Vin. 0090567
    

14Back to top Go down   How to ride home when your fuel pump fails Empty ride home on Sun Mar 08, 2020 7:10 am

daveyson

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Here's a photo of the mighty beast that inspired this journey.
I took it for a spin today. 
Because of its unregoness,
You hardly ever see the mighty beast down here
He only come to town about twice a year.How to ride home when your fuel pump fails 01711



Last edited by daveyson on Wed Jul 08, 2020 4:03 am; edited 7 times in total (Reason for editing : trying to delete a photo double)


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11/1985 bmw k100rt (late model)  Vin. 0090567
    

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