Fuel Pump Controller Operation

[kthutchinson]

I recently experienced a fuel pump controller failure on my 2007 R1200ST. After getting the bike back on the road, I got to wondering about how the controller actually operates. I know the fuel pump runs for a second or so when the ignition is first turned on to pressurize the fuel system. My questions are:

1. When the engine is running, does the pump operate continuously at full speed, or does the controller moderate the pump speed?

2. If the controller moderates the pump speed, what parameters are used to determine the speed?

 

[mneblett]

I recently experienced a fuel pump controller failure on my 2007 R1200ST. After getting the bike back on the road, I got to wondering about how the controller actually operates. I know the fuel pump runs for a second or so when the ignition is first turned on to pressurize the fuel system. My questions are:

1. When the engine is running, does the pump operate continuously at full speed, or does the controller moderate the pump speed?

2. If the controller moderates the pump speed, what parameters are used to determine the speed?

1. Moderates pump speed.

2. Fuel pressure.

The pump is modulated to maintain constant fuel pressure.

 

[kthutchinson]

mneblett,

I thought maintaining constant fuel pressure was the purpose of the mechanical fuel pressure regulator. There is no fuel pressure sensor on the hexheads, so how would the ECU determine what speed to run the pump?

 

[mneblett]

mneblett,

I thought maintaining constant fuel pressure was the purpose of the mechanical fuel pressure regulator. There is no fuel pressure sensor on the hexheads, so how would the ECU determine what speed to run the pump?

Absolutely right! Got my bikes swapped -- BMW's moved/moving to return-less systems and I had a brain-blank moment.

Edit -- the FPC does control pump speed. (I need to refresh myself on why)

 

[jeffkruger]

I experienced a controller failure on my 07 GSA prior to it becoming a somewhat well known issue. After it was replaced I purchased a controller bypass cable from Burns Moto. If the controller fails again I can bypass it with the cable and keep on riding. With the bypass cable in place the pump runs continuously, which is how I understand previous years actually operated. Unused fuel is routed back to the tank.

The cable needs a SAE 2 prong plug to operate. Same plug a battery tender or Gerbings heated gear plug in to. I have the bypass cable on the bike at all times.

 

[kthutchinson]

Jeff,

I plan to make a bypass cable out of my failed controller.

mneblett,

I suppose the ECU could modulate fuel pump speed based on rpm and engine load (throttle position), just like a fuel or ignition map. However, with BMW's and Bosch's secretive attitude to the internal workings of their products, we may never know for sure.

 

[jeffkruger]

Jeff,

I plan to make a bypass cable out of my failed controller.

mneblett,

I suppose the ECU could modulate fuel pump speed based on rpm and engine load (throttle position), just like a fuel or ignition map. However, with BMW's and Bosch's secretive attitude to the internal workings of their products, we may never know for sure.

Using the connector off the failed unit to make one is a good idea.

Burns Moto has them that will plug into a BMW powerlette plug to power the bypass as well.

 

[PGlaves]

I suspect that BMW found the answer to a question that didn't need to be asked, by way of buying off-the-shelf fuel pump units used elsewhere in the automotive world. The old system worked well - the new system less well. The original controllers suffered corrosion when water collected in the sump shaped recess where the controllers were mounted. New revised units helped a lot, it seems. Progress?? Sometimes it is one step forward, two steps back.

 

[jeffkruger]

I suspect that BMW found the answer to a question that didn't need to be asked, by way of buying off-the-shelf fuel pump units used elsewhere in the automotive world. The old system worked well - the new system less well. The original controllers suffered corrosion when water collected in the sump shaped recess where the controllers were mounted. New revised units helped a lot, it seems. Progress?? Sometimes it is one step forward, two steps back.

That sure seems to be the case with a lot of things anymore doesn't it? Modern brakes, ABS and a host of other things make bikes safer. Liquid cooling lets them make more power and run cooler. A lot of it comes at the expense of being more complicated, less user friendly from a maintenance standpoint, etc. All of us probably have differing opinions and levels of what we will tolerate or find desirable. I really like the new WC boxers and realize where they are superior to my 07 GSA hexhead. For me, my bike makes enough power, and with custom suspension made for me by Ted Porter, handles the various ways I ride and load the bike well without adding any electronic suspension controls. I like the simple valve adjustments, even though they're more frequent than the newer bikes. Luckily my bike was late 07 production so it has the FD drain at 6:00. Every bit of maintenance from the day it was new has been done by me. It's gone to dealers for recall work and warranty repairs. There have been a few recalls, from the antenna ring, brake line, rear wheel flange, and a couple of other things. A fuel pump controller failed under warranty and the clutch master cylinder failed under warranty, and I am on my 5th fuel strip sensor. I am happy with the bike and feel like I know it. The clutch master cylinder failed during a trip and BMW Roadside assistance took care of getting the bike to A&S BMW (great dealership). They didn't have a clutch master cylinder in stock so took one off a showroom bike to put on mine and got me back on the road. Hard to fault that kind of service. The fuel pump controller also failed during a trip. BMW Roadside Assistance took care of getting it to the nearest dealer. Unfortunately that dealer thought they could just clean the connections on the controller, and they did that and sent me down the road. I made it about 30 miles before it happened again. The dealer sent an employee with a trailer and got the bike back to the dealership. Unfortunately they didn't have a controller in stock (maybe why they sent me down the road like they did the first time?). I got a hotel for the night and arranged for my wife to pick my daughter and I up the next day. When the bike was ready to pick up my wife and I rented a one way rental car to drive and pick up the bike. I sent the receipts for the hotel and meals, along with the rental car receipt and my wife's gas receipt when she picked us up and sent them off to BMW Roadside Assistance. Fairly quickly I had a check reimbursing me for everything. Stuff happens, and it can be a bummer, but I was extremely pleased with how everything went other than being sent down the road with a bad controller.

Innovation happens, and depending on your viewpoint, some of it is great, and some is downright horrible. I have tried to learn to appreciate and enjoy what I have, including my GSA. Thankfully there are many reasons it serves my needs well and still puts a big smile on my face.

 

[Omega Man]

This Best of Forum-
http://forums.bmwmoa.org/showthread.php?55047-Everything-you-wanted-to-know
Has some good info on FPC's
OM