Unusual problem.

[Steptoe]

My 2003 17k mile 1150 RT recently started to kangaroo and jerk around, sometimes stalling when pulling away and bogging down requiring plenty of revs and clutch use to keep up momentum. Initially thought it was water in the fuel tank. Attached a pipe to the return hose and started up bike to drain the tank... no fuel coming from the return fuel line with the engine running, but fuel coming out of the fuel supply line. So that’s either a blocked return on the fuel pressure regulator or something going on in the tank.... removed fuel pump housing to check everything inside and found all the fuel hose inside the tank had gone soft, rubbery and was bulging. This was blocking the fuel filter, causing low fuel pressure, so low that it wasn’t enough to get any fuel returning to the tank.. new filter and internal hoses, Pump cleaned out and it feels like a new bike. Looking at the state of the hoses I’m amazed it run at all.

 

[gog]

had the same issue a year or so ago. replaced all internal hoses and used a metal U bend (think theyre made for some kind of beer brewing apparatus) in place of the expensive pre-formed BMW part from pump to filter.

i know youre new to spannering and BMW bikes, so youre forgiven for not knowing of this common problem.

 

[DrFarkoff]

Had that a few times on K100's fuel pump damper/mount rubber


Only 2 Oilheads 2 x R1100RS and 1 x 1150RT that I had to fix

I never did find out "why" just the hoses went all gummy

 

[Mzokk]

I’d say low mileage and age is the issue. Hoses being dried out then exposed to fuel dried out exposed to fuel etc.. Ethanol in the fuel probably doesn’t help. I could of course be talking bollocks

 

[beanwood]

I have an issue with my 1150GS. Starts fine, but if you try and give it a handful of throttle from low revs or idle, it 'dies' a little before picking up again. Very disconcerting when trying to pull away on a roundabout ....
It's been stood for a long while with minimal fuel in the tank. I need to start the diagnostic somewhere - and spongy pipes seems like a reasonable place. I'll stick a new filter and pipes in, as I know they're 25 years old, but are there any tips on removing the pump housing? I saw @Steptoe mention somewhere about a soldering iron on 'the usual suspect' nuts - which would those be? I'll order a new O ring - is that to be held in with silicon, or is there a special rubber grease?
I REALLY don't want it to leak afterwards (Which is what's stopped me changing it so far)

 

[johnnyboy]

My 2003 17k mile 1150 RT recently started to kangaroo and jerk around, sometimes stalling when pulling away and bogging down requiring plenty of revs and clutch use to keep up momentum. Initially thought it was water in the fuel tank. Attached a pipe to the return hose and started up bike to drain the tank... no fuel coming from the return fuel line with the engine running, but fuel coming out of the fuel supply line. So that’s either a blocked return on the fuel pressure regulator or something going on in the tank.... removed fuel pump housing to check everything inside and found all the fuel hose inside the tank had gone soft, rubbery and was bulging. This was blocking the fuel filter, causing low fuel pressure, so low that it wasn’t enough to get any fuel returning to the tank.. new filter and internal hoses, Pump cleaned out and it feels like a new bike. Looking at the state of the hoses I’m amazed it run at all.

Sounds like a decent mechanic sussed that one out for you

 

[beanwood]

Sounds like a decent mechanic sussed that one out for you

I’m trying to work smarter not harder

 

[Littledumptruck]

When ever I fill my R850GS to the brim, if I park up on the side stand she starts dribbling fuel out. I have to remember to park on the centre stand, but only if parking straight after filling. Do a few miles and she’s fine. Someone once told me the internal pipe must be split, somewhere near the top, but I wonder if the cap seal is letting by. Not a huge issue hence I’ve never looked into fixing it.

 

[johnnyboy]

I’m trying to work smarter not harder

I was taking the piss out of Steptoe....

 

[Ian J Hartley]

When ever I fill my R850GS to the brim, if I park up on the side stand she starts dribbling fuel out. I have to remember to park on the centre stand, but only if parking straight after filling. Do a few miles and she’s fine. Someone once told me the internal pipe must be split, somewhere near the top, but I wonder if the cap seal is letting by. Not a huge issue hence I’ve never looked into fixing it.

You are pressurising the fuel tank. Cold fuel from the pump will expand in the warm tank. You have brim filled it so there is a smaller air gap for expansion. So the fuel is probably leaking past the internal tank check valve which under normal conditions would prevent excess fuel from being dumped overboard if the tank was unpressurised.

Next time you brim fill the tank and it starts to dribble fuel. Try gently opening the filler cap, you should hear the air hissing out. Don’t do it quickly else the fuel will blow out from the filler all over your tank.

I never brim filled it and park up.

 

[jefformston]

When ever I fill my R850GS to the brim, if I park up on the side stand she starts dribbling fuel out. I have to remember to park on the centre stand, but only if parking straight after filling. Do a few miles and she’s fine. Someone once told me the internal pipe must be split, somewhere near the top, but I wonder if the cap seal is letting by. Not a huge issue hence I’ve never looked into fixing it.

My 1150 does the same, I’ve always assumed fuel gets past the cap seal and then down the overflow. I do the same just park on the main stand if I’ve just filled up, with the bike on the main stand. Doesn’t happen if you just fill when on the side stand.

 

[beanwood]

are there any tips on removing the pump housing? I saw @Steptoe mention somewhere about a soldering iron on 'the usual suspect' nuts - which would those be? I'll order a new O ring - is that to be held in with silicon, or is there a special rubber grease?
I REALLY don't want it to leak afterwards (Which is what's stopped me changing it so far)

Before we get too sidetracked on overfilling the fuel tank, I'm still needing answers to this one guys (I know - it's all about me, me,me.... pretty please...)

 

[Wrigsby1]

Have a look at it removed... You're hunting in the dark without seeing if it looks bad... The nuts will be the ones around the pump housing and no, I've never used anything on the o-ring... There you go... You have a starting point...
Once apart things may become clearer and for most on here, your symptoms may lead to a handful of things and diagnosis is mostly made by being there...

 

[Ian J Hartley]

I saw @Steptoe mention somewhere about a soldering iron on 'the usual suspect' nuts - which would those be?

They will be the nuts holding the pump plate. Heat will expand the nuts and soften the nylon inserts so they are less prone to shearing the studs when removing.

When refitting use a screwdriver with socket so as not to apply too much torque which will likely shear the bolts.

 

[Littledumptruck]

I never brim filled it and park up.

Kinda hard not to if you’re meeting up with a group for a ride that you don’t know or have control of where the next fuel stop is, especially when most ride GSAs and don’t always think of how far a lesser bike can go.

 

[Aidan1150]

They will be the nuts holding the pump plate. Heat will expand the nuts and soften the nylon inserts so they are less prone to shearing the studs when removing.

When refitting use a screwdriver with socket so as not to apply too much torque which will likely shear the bolts.

There are, if memory serves six of them and they are 8mm nuts. If you have time to give them a 24hr soak in a good penetrating fluid that will surely help. As Ian says, a bit of heat and be really gentle as they are quite easy to break if you go at them in gorilla mode. I usually give the threads a dress with a soft (copper) brush and apply copperslip grease to them and always use new nuts liberally greased. The O-ring should be fine but if you are changing the filter, checking the internal pipes etc then you might as well fit a new one. As Wrigsby points out there is no need to apply anything to the O-ring.

Take your time and it should be grand.

 

[Mzokk]

When you get the plate off and put it back on again you can slather the bottom of the tank including the plate with waxoyl dinitrol or whatever rust protection potion you have to hand. Makes getting the little blighters back off a breeze, to change the fuel filter, and keeps the bottom of your tank from rusting.

 

[Ian J Hartley]

Kinda hard not to if you’re meeting up with a group for a ride that you don’t know or have control of where the next fuel stop is, especially when most ride GSAs and don’t always think of how far a lesser bike can go.

You can try leaving the filler cap down but not locked. This will prevent the tank from pressurising. It’s what I do on those rare occasions when you fill up and have a break before riding off.

 

[Arsey]

My 2003 17k mile 1150 RT recently started to kangaroo and jerk around, sometimes stalling when pulling away and bogging down requiring plenty of revs and clutch use to keep up momentum. Initially thought it was water in the fuel tank. Attached a pipe to the return hose and started up bike to drain the tank... no fuel coming from the return fuel line with the engine running, but fuel coming out of the fuel supply line. So that’s either a blocked return on the fuel pressure regulator or something going on in the tank.... removed fuel pump housing to check everything inside and found all the fuel hose inside the tank had gone soft, rubbery and was bulging. This was blocking the fuel filter, causing low fuel pressure, so low that it wasn’t enough to get any fuel returning to the tank.. new filter and internal hoses, Pump cleaned out and it feels like a new bike. Looking at the state of the hoses I’m amazed it run at all.

Take it to a good mechanic and get it sorted

 

[The Other PaulG]

Before we get too sidetracked on overfilling the fuel tank, I'm still needing answers to this one guys (I know - it's all about me, me,me.... pretty please...)

I would share your (seemingly unnecessary) worries about the tank sealing - it does feel odd to have a big access plate below the normal fuel level.

However…given the symptoms, the anecdotal wisdom here and age of the bike it sounds highly possible this could be your issue and is good preventative maintenance anyway.

It’s clearly a job that’s not complex, but requires time and patience. So the best person to do it is you.