R1150RT fuel pump failure warning signs

[rogerc60]

My RT left me stranded a few nights ago. The motor suddenly just died while I was riding. I managed to coast into a store parking lot and got the bike towed home.

When I got it home and started testing things out I noticed the fuel pump was not running when I switched on the ignition. I found the fuel pump fuse was blown; replaced that and now the pump runs and the bike starts and runs fine. But listening to the the pump run for that one second at key on, it sounds like it's straining: not a nice smooth hum like it's always done before.

Given that sound and the fact that the fuse blew I'm suspecting the pump is going bad. Does that sound like a correct diagnosis? I have a fuel pump kit on order from Beemer Boneyard.

Thanks for any and all advice!

 

[roger 04 rt]

It sounds like the right diagnosis. Make sure you also replace the vibration damper at the rear of the pump. While you have the tank open consider replacing the hoses. They can look good but be near failure.

Here’s a way to test things before you open the tank: https://forums.bmwmoa.org/showthread.php?69157-R1150-Fuel-System-Diagnostic-Tool

You only need the return line hose, not the pressure gauge.

 

[jagarra]

It always a good idea to check and replace the fuel hoses when doing annual maintenance like bleeding brakes. This year when I had the tank off to do the brakes I decided to open the tank up to check things out, even though I had replaced filters and the pump pad when I bought the bike about 5k ago. I had bought a new U shaped hose and submersible fuel lines from the dealer, months ago JIC since everything else was 25 years old.

Here is what i found when I opened the tank: even though there were no symptoms of anything wrong there was a pending failure waiting to happen out in the middle of no where.

 

[gsaddict]

A good alternative to the BMW OE U hose 16 14 2 325 808 at $50 is the Holley 12-728 hose (less than $10)
The Holley part will not rot over time.

I have successfully used it in several oilheads including my own. https://advrider.com/f/threads/r1150-in-tank-fuel-hose-holley.1228951/

I have done pressure tests on it as well.
Be sure to use the proper fuel injection clamps when installing.

 

[rogerc60]

Here’s a way to test things before you open the tank: https://forums.bmwmoa.org/showthread.php?69157-R1150-Fuel-System-Diagnostic-Tool

Thanks, Roger. I still have the plastic QDs on my bike, planning to replace them this winter. This just might persuade me to accelerate my timetable.

 

[rogerc60]

Update. After breaking one of the plastic fuel quick disconnects (@$_#_$#$$$**) and receiving the all-metal replacements from Beemer Boneyard I ran roger 04 rt's diagnostic. I'm happy to report my fuel pump produced just under 3 liters in one minute. Nothing wrong with any parts inside the tank

So I'm left with question of the blown fuse. For now I'm chalking it up to old age, and I'm going to replace all the other 16-year-old fuses in the box as a preventative measure.

 

[dieselyoda]

There is also something called electromagnetic capacitance or some such big words like that.

Essentially, when a motor turns, it creates a magnetic field. When that magnetic field collapses, it will create voltage. It's almost the same as how an ignition coil works.

When electric fuel pumps started becoming popular in machines, I had hair and could get any red-head I wanted just by my good looks. We had lots of dead iron come in with blown fuses to the fuel pumps. There was nothing wrong with fuses and they didn't blow because of amperage, they blew because of voltage.

The solution was to increase the amperage of the fuse or use a circuit breaker. That solution burnt points in the relay and the ultimate fix was to wrap the fuel pump wires in tin foil. The tin foil acted like a big condenser.

I need to use both hands to count how many electric fuel pumps I have changed because they went open or short after 40 years.

I can't count high enough to tell you how many got changed because if the fuse blew, it had to be the pump.

Now, I count on my charm, wit and fashion sense to chase red-heads.

 

[gsaddict]

A good explanation....
https://www.youtube.com/watch?v=RXJKdh1KZ0w

 

[tangoalpha]

A good explanation....
https://www.youtube.com/watch?v=RXJKdh1KZ0w

Clearly the answer to the problem is that he failed to connect the carbadoobalator to the bifarkle valve. [emoji23]


Sent from my iPhone using Tapatalk

 

[rogerc60]

A good explanation....
https://www.youtube.com/watch?v=RXJKdh1KZ0w

Yeah, that explains a lot. Looks like I've been doing engineering all wrong all this time

 

[rogerc60]

There is also something called electromagnetic capacitance or some such big words like that.

Essentially, when a motor turns, it creates a magnetic field. When that magnetic field collapses, it will create voltage. It's almost the same as how an ignition coil works.

I've known about inductive kick for a long time, having used snubber diodes on relay coils. It never occurred to me that the same applies to DC motors, but it makes sense.