BMW R1200RT/R1250RT Forum

OK, on my second RT-P and seems to also have a fuel system issue. The pump in the bike DOES NOT prime when the key is switched on. I have a brand new in box oem fuel pump assembly and a spare FPS attached to it that I connected and that also DOES NOT prime on the key turn.

Believe I was told on my first go around that there are no fuses/relays that drive the pump. The only issue I can see is the the bike is equipped with an auxiliary battery, however, that battery is missing. I cant imagine the the auxiliary battery is integral to the basic operation of the bike, but I am not the smartest tool in the shed either. Is that an open circuit that needs to be closed in order for the system to operate?

Also add that both the pump that was in it and the new one have the newer style black powder coated FPC's and neither have any degradation on the underside resin.

Any ideas as to why it would not be powering up the fuel pump? I do hear the stepper motor in the throttle body zeroing. The bike will turn over but obviously no fuel. The tank is also bone dry as I cleaned it, but cant imagine that has anything to do with it either?

Thanks in advance for any suggestions. -Doug

This thread from ukGSer, https://www.ukgser.com/forums/showthrea ... ry-battery would suggest that the auxiliary battery is not needed to run the bike.

Thanks @David. I figured as much. The bike does have the emergency lights installed and they are NOT working. I think they are likely connected to the missing aux battery and is why they are not working, but everything else is coming on as it should, lights, stepper motor, the starter engages, the turn signals work, parking lights come on.

Have you tried cranking the engine, I have read that the fuel pump only runs when cranking or the engine is running. Don't know myself whether this is true or not.

When you fitted the new pump, did you swap the controller over or fit a new one?

Glenn wrote: ↑Sun Jan 22, 2023 9:20 pm When you fitted the new pump, did you swap the controller over or fit a new one?

I had a spare USED FPC that came off my previous RT-P. That bike had a badly degraded pump that I replaced with a used pump that came with an FPC. So the one I am using on the new pump is used. It is POSSIBLE it is bad, I don't know how to test it.

There is also an FPC on the pump that came with the bike. So.... I have 2, but they are both used and I cannot verify that either works. All I can state is that they are both the newer style black powder coated, neither show any sign of degradation on the underside.

I do think that is a possibility, is there a test I can perform to verify that one or both are working or not?

David. wrote: ↑Sun Jan 22, 2023 8:57 pm Have you tried cranking the engine, I have read that the fuel pump only runs when cranking or the engine is running. Don't know myself whether this is true or not.

I did crank it and no change, although to be fair, I only cranked it for a second, I did think the same thing that turning the engine over may engage the pump, but my past experience has been that if it doesn't prime when the key is turned on, there is a fault somewhere.

How about removing the FPC and bypassing it like this.

***UPDATE***

I tested the connections and was getting power to the FPC, AND to the pump (through the FPC) WHILE the starter is engaged. NO IDEA why it is not priming. I understand that the control unit won't continually prime it or prime it every time you turn the key, so I had waited for an hour between cycling the key to make sure I hadn't missed the brief "whirr" of the pump priming. Still no idea why it does not. In fact, it takes a millisecond after the starter is engaged for the pump to engage.

BUT, with the starter engaged, BOTH FPC's and BOTH pumps work (obviously one is brand new) but the "original" is also working so for now, I am going to leave the original pump in there and hold on to the new one for potential future use.

Thanks for the assistance, I am going to finish up the basic maintenance. It has fresh oil (Castol GTX Dino 20/50). It will have all four plugs OEM NGK's, air filter, oil filter and fresh gas and then assume it will fire off.

If you watched the video, I refitted the right side throttle body into the intake boot/manifold and put a new clamp on it.

Again, the bike only has 7300 miles on it, it turns over freely and I am expecting it will fire and run as it should. Thanks again for the help!!

SD1 wrote: ↑Sun Jan 22, 2023 10:52 pmI tested the connections and was getting power to the FPC, AND to the pump (through the FPC) WHILE the starter is engaged. NO IDEA why it is not priming. I understand that the control unit won't continually prime it or prime it every time you turn the key, so I had waited for an hour between cycling the key to make sure I hadn't missed the brief "whirr" of the pump priming. Still no idea why it does not. In fact, it takes a millisecond after the starter is engaged for the pump to engage.

Checked my 2012 Camhead this morning, when switching on the ignition only, I did not hear the fuel pump running (priming).

Your tests seem to confirm that the fuel pump only runs when cranking to start or the engine is running. Is this correct.

Just a thought, perhaps the reason why the fuel pump doesn't prime when the ignition is switched on is that AFAIK, the fuel lines between the tank and injectors remain pressurised all the time.

@David. I don't know for certain, I can state that my previous RT-P, also an 09' did prime. It had a badly degraded fuel pump when I received it that required a replacement pump. Once I had sorted that out, it would prime the fuel system with a .5 second pulse of the fuel pump when you turned the key on. I do agree that once the system is pressurized, assuming its in good working order, it should maintain that pressure for some period of time even after the pump is turned off.

So, still not sure why the previous bike did one thing and this one is doing something else, but, this one had been idle for a very long time, maybe north of a year or possiblly longer. I am finishing up the service this afternoon. I am installing the new plugs and putting some fresh Petrol in the bike and we will see if we get the desired result. I will report back. It will be interesting to see if anything changes once the bike is back in service and operated on the regular.

**UPDATE**

Bike is running. I refitted the fuel pump, swapped out the plugs (old ones looked ok) and threw some fresh Petrol in the tank and it fired right up.

BUT.... def some issue with the drivetrain. I did not attempt to ride it, but it did not go into gear easily and doesn't seem to have much clutch bite once its in gear. I did not check the clutch fluid or attempt to service/bleed the system, I will post a separate thread to trouble shoot that issue.