BMW K bikes (Bricks)


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MikeisonTV

MikeisonTV
Silver member
Silver member
Bottom 7.5 fuse keeps blowing and now fuel pump isn't working. Are these too the same problem? As in, does the fuel pump need that fuse to power (spin)? 

What can I do to figure out why that fuse keeps popping?

Thanks gents.

Bottom 7.5 fuse keeps blowing and now fuel pump isn't working. B1B2DDEA-5F8B-4F81-BA1B-89733D53E850


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Yep! I'm flipping through the air....that ain't good.
    

Rick G

Rick G
admin
admin
The #7 fuse feeds the horn relay and the flasher unit. It should have no bearing as to the fuel pump working or not.
Check the 4 pin plug that goes to the tank they are noted for problems, you may need to squeeze the female pins so they make good contact or just cleaning it may work. I have replaced two of those over the years with 4 pin 6mm automotive type connectors and have had no more trouble.
As for the fuse blowing you will need a good circuit diagram to chase the problem down. If you need one PM me and I will give you a link.


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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 1999 K1100 LT with a Big Block 1200
    

MikeisonTV

MikeisonTV
Silver member
Silver member
I'll try the 4 pin under the tank in the morning and see if the pump will spin. She just slowly choked out and died. Gas was pretty low so I hoped that was the culprit turns out to be more. Please do send the diagram link for the fuse when you get a second. Thank you so much Rick. 

PM sent


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Yep! I'm flipping through the air....that ain't good.
    

kennybob

kennybob
Silver member
Silver member
The fuel pump runs on fuse #6, which it appears you are missing.

    

Holister

Holister
Life time member
Life time member
MikeisonTV wrote:Bottom 7.5 fuse keeps blowing and now fuel pump isn't working. Are these too the same problem? As in, does the fuel pump need that fuse to power (spin)? 
I think Mike is referring to the "bottom 7.5amp fuse" which is #6 (the missing one).
If this is the case then the fuel pump windings or fuel level sender may be shorted. Fuse #6 also goes to the temperature controller. Try pulling the temp controller first and see if the fuse blows. Then disconnect the pump or visa versa. It's likely going to be the pump. When did you last change the fuel filter?


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1989 K100RT     VIN  0097367 (naked)  
1996 K1100RS   VIN  0451808
 Bottom 7.5 fuse keeps blowing and now fuel pump isn't working. Austra12    Fuel:  95 Octane
Engine Oil: Nulon Full Synthetic 15W50
Gear Box Oil:  Nulon Synthetic 75W90
    

duck

duck
Life time member
Life time member
To test the fuel pump you can jump 12V directly to it. The smaller diameter terminal on the pump is 12V+.

Probably a good idea to make a point of not creating sparks in the fuel tank when doing this. i.e. Connect leads to the fuel pump first, then your power supply outside of the tank.


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Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT
91 K1
93 K75S (K11 front end)
91 K75S (K1 front end)
14 Yamaha WR250R
98 Taxi Cab K1200RS
14 K1600GT
http://www.ClassicKBikes.com
    

kennybob

kennybob
Silver member
Silver member
delete



Last edited by kennybob on Thu Jun 23, 2016 10:33 pm; edited 5 times in total

    

Holister

Holister
Life time member
Life time member
Mike. Does the fuse blow....

  1. As soon as you put it in
  2. When the ignition key is turned on
  3. When you press the starter







EDIT: due to kennybob's post being completely altered, I've deleted my response because it was not relevant.



Last edited by Holister on Thu Jun 23, 2016 8:16 pm; edited 1 time in total


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1989 K100RT     VIN  0097367 (naked)  
1996 K1100RS   VIN  0451808
 Bottom 7.5 fuse keeps blowing and now fuel pump isn't working. Austra12    Fuel:  95 Octane
Engine Oil: Nulon Full Synthetic 15W50
Gear Box Oil:  Nulon Synthetic 75W90
    

Inge K.

Inge K.
VIP
VIP
kennybob wrote:The radiator fan is likely locked up and the stall current is blowing fuse #6.

The fan motor is protected by fuse #7, beside the fuel pump fuse #6 protects the PCB inside the temp management relay.


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Inge K.
K100RS -86. (first owner), K1100LTSE -94.
    

MikeisonTV

MikeisonTV
Silver member
Silver member
I meant to update sooner. RICK nails it again...tighten up the 4 pin connector under the tank...she fired right up. Cool


__________________________________________________
Yep! I'm flipping through the air....that ain't good.
    

Holister

Holister
Life time member
Life time member
kennybob wrote:Just to quickly test if the pump is working and to avoid sparks in the tank, with the key off, you could put a jumper wire from the right-hand side of fuse 4 to the left side of fuse 6 to put power to the fuel pump.

This is a test, it is only a test.  Do not try to operate in such a manner.
The proper way to test the pump is to isolate it first, away from the circuit that's causing the short. In any case the fuse would blow straight way again so you'd be none the wiser. Don't even think about trying that without a fuse.


__________________________________________________

1989 K100RT     VIN  0097367 (naked)  
1996 K1100RS   VIN  0451808
 Bottom 7.5 fuse keeps blowing and now fuel pump isn't working. Austra12    Fuel:  95 Octane
Engine Oil: Nulon Full Synthetic 15W50
Gear Box Oil:  Nulon Synthetic 75W90
    

Holister

Holister
Life time member
Life time member
MikeisonTV wrote:I meant to update sooner. RICK nails it again...tighten up the 4 pin connector under the tank...she fired right up. Cool
most often its the simple solution. Onya rick.

So whats causing the fuse to blow?


__________________________________________________

1989 K100RT     VIN  0097367 (naked)  
1996 K1100RS   VIN  0451808
 Bottom 7.5 fuse keeps blowing and now fuel pump isn't working. Austra12    Fuel:  95 Octane
Engine Oil: Nulon Full Synthetic 15W50
Gear Box Oil:  Nulon Synthetic 75W90
    

MikeisonTV

MikeisonTV
Silver member
Silver member
Holister wrote:
MikeisonTV wrote:I meant to update sooner. RICK nails it again...tighten up the 4 pin connector under the tank...she fired right up. Cool
most often its the simple solution. Onya rick.

So whats causing the fuse to blow?
The fuse seems to be ok now

I reconfigured my DIY mustang fuel pump design by:

1: gutting a dead BMW fuel pump for the metal housing
2: I bought a Carquest E2024 fuel pump from eBay seller Herko and Genuine Walbro Fuel Pump Sleeve 122-3074 submersible foam noise suppressor sleeve on eBay
3: the pump fits super snug in the sleeve, the sleeve then super snug in the gutted BMW pump housing. Since the black rubber on the pump mount has been falling apart over the years...I cut the "distended rubber off at the bottom. I added a screw tightening o clamp to the top for added security.


My guess is the first shitty design I had was maybe shorting the fuse as one of the wires might have touched the other when it fell through the orginal mount...but I'm more of a designing brain and a wrench than an electrician...


Finally bought a TRUE RMS multimeter so I can stop shying away from electrical gremlins like you pros 


__________________________________________________
Yep! I'm flipping through the air....that ain't good.
    

MikeisonTV

MikeisonTV
Silver member
Silver member
duck wrote:To test the fuel pump you can jump 12V directly to it. The smaller diameter terminal on the pump is 12V+.

Probably a good idea to make a point of not creating sparks in the fuel tank when doing this. i.e. Connect leads to the fuel pump first, then your power supply outside of the tank.
That's exactly how I did it. I clean the pumps using the same DIY method used for cleaning the fuel injectors.

Using a battery, carb cleaner, and a tire valve stem like this:
(no need to melt if you drill the hole in the tire valve stem one size narrower  than the red straw)


__________________________________________________
Yep! I'm flipping through the air....that ain't good.
    

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