Fuel pump alternative replacement

dancata · Nov 6, 2009

Hi all,

My 1100gs's fuel pump died a few days ago; I could not hear the bzzzzzzt when ignition was switched on; so I took it off from the fuel tank, and applied 12V directly on the terminals, but nothing. And the relays are ok, so is the fuse for it.

As you may know, the OEM BMW pump costs 328$ from the dealer, or as a alternative, 100 euros + shipping from Euro MotoElectrics and a 2 week waiting period for shipping for a Bosch fuel pump.

My concern right now is if I can use a much cheaper car gas pump.
So the fuel pump is characterized by fuel pressure and delivery volume; for 1100gs, these values are 3 bar and 110 liters/hour. If I can find a similar size pump from a car parts shop that has the same pressure but lower or higher delivery volume, will it work on my bike?

Thanks,
Dan.

Stewart H · Nov 6, 2009

I have read somewhere on the internet that a BMW 3 series car uses a pump that will fit, I keep meaning to go to the car yard to look at some pumps, I think some tosser got his bike fixed somewhere in Eastern Europe using an Audi one :nenau

Stewart

Packer · Nov 6, 2009

Euro Car Parts stock a lot of components for european cars. Not surpringly

I just looked at a BMW 316 91-99 model year as an arbitrary example and they list pumps from around £60-£70.

http://www.eurocarparts.com/ecp/c/BMW_3+Series_316_1.6_1999/p/Car-Parts/Engine-Parts/Fuel-and-Engine-Management/Fuel-Pumps-and-Parts

dancata · Nov 6, 2009

Is there a problem if the auto fuel pump has 3,5 bars pressure? Will that destroy my fuel pressure regulator?

Thanks,
Dan

Stewart H · Nov 6, 2009

K bikes use 3.5 bar regulators, the pump just pumps, the regulator controls pressure by letting the excess go back to the tank.
Stewart

dancata · Nov 8, 2009

Just finished my bike; I have used a Renaul Dacia Logan fuel pump, it costs 20 euros! And the result is the same, the bike runs just like before, only the bzzzzzzt is somehow different

The new pump is 3,5 bars, the broke original bmw pump had 3 bars pressure; next mod will be the 3,5 bar k1200 fuel pressure regulator.

Thanks,
Dan.

sockpuppet · Nov 8, 2009

Why not speak to Sherlocks. They have second hand pumps for £60.

dancata · Nov 8, 2009

sockpuppet said:
Why not speak to Sherlocks. They have second hand pumps for £60.

Because I am in Romania, also have to pay shipping; and this pump has 2 year warranty.
And the fuel pump is a serviceable, just like clutch, brakes and oil.

Stewart H · Nov 8, 2009

dancata said:
Just finished my bike; I have used a Renaul Dacia Logan fuel pump, it costs 20 euros! And the result is the same, the bike runs just like before, only the bzzzzzzt is somehow different

The new pump is 3,5 bars, the broke original bmw pump had 3 bars pressure; next mod will be the 3,5 bar k1200 fuel pressure regulator.

Thanks,
Dan.

That is my kind of price :thumb2

did you take your old pump to a car parts shop?

Stewart

dancata · Nov 9, 2009

Stewart H said:
That is my kind of price did you take your old pump to a car parts shop?

Stewart

No, I still have my old pump.

When I applied 12V on it last night, it only worked (spinned) if I also applied a shock/bump on it; if gentle contact to battery terminals, nothing happens, only a small tick or something.

I know the original pump is like a capsule but can it be repaired? It's not burnt, because it spins, so I think only the contacts inside it are broke.

And some other thing I do not understand... How can a k1200 FPR give you more boost in overtakes if the original pump only delivers 3 bar pressure?
Can't wait for the first snow to come, so I can change my FPR to a 3,5 bar one, since my pump is also 3,5.

Thanks a lot guys!

MattW · Nov 9, 2009

Good find Dancata :thumb2

Regarding the regulator....
My knowledge of fuel injection systems is sketchy, but wouldn't changing the regulator to a higher pressure one mean that the bike over fuels - as I understand it, fuelling is governed by the 'open' time of the injector and the injection rail pressure, so given that the 'open' time won't change, higher pressure must mean more fuel?

I could be (and quite probably am) speaking rubbish though

dancata · Nov 9, 2009

MattW said:
Good find Dancata

Regarding the regulator....
My knowledge of fuel injection systems is sketchy, but wouldn't changing the regulator to a higher pressure one mean that the bike over fuels - as I understand it, fuelling is governed by the 'open' time of the injector and the injection rail pressure, so given that the 'open' time won't change, higher pressure must mean more fuel?

I could be (and quite probably am) speaking rubbish though

I agree. The injector stays open the same amount of time no matter what FPR or fuel pump I use.

Maybe someone who has actually done this can write here the pro's and con's of using another FPR than the one designed for the bike.

ahutcheon · Nov 9, 2009

dancata said:
I agree. The injector stays open the same amount of time no matter what FPR or fuel pump I use.

Maybe someone who has actually done this can write here the pro's and con's of using another FPR than the one designed for the bike.

If your bike has a lambda sensor, I think the Motronic will vary the injector duty cycle to try and keep average stoichiometric mixture (so more pressure will reduce injector opening) while it is running closed-loop (e.g. part-throttle cruising).

I think there will also be times (perhaps including full throttle) where the system runs open loop, using a fixed map rather than lambda feedback to decide injector opening. Then, more fuel pressure will lead to richer mixture (does this mean more power? what does it do to economy...).

Disclaimer: I've never experimented, just have some theoretical knowledge from working in automotive electronics.

Paul Young · Nov 9, 2009

Steptoe posted something on this a few years ago & I changed my FPR for the K1200 a year or so later. However, I also have a Powercommander fitted & that makes adjustments to the fuelling so it runs to the custom map that's been programmed into it. 3.5 bar pressure just gives a snappier throttle response - but it's great for overtakes...

dancata · Nov 9, 2009

Paul Young said:
Steptoe posted something on this a few years ago & I changed my FPR for the K1200 a year or so later. However, I also have a Powercommander fitted & that makes adjustments to the fuelling so it runs to the custom map that's been programmed into it. 3.5 bar pressure just gives a snappier throttle response - but it's great for overtakes...

So a PCIII and a 3,5 bar FPR gives a snappier throttle response.
I am wondering if a 3,5 bar pump + a 3,5 FPR on my stock 1100GS and a CO2 potentiometer adjustment would do the same thing.

sproggy · Nov 9, 2009

dancata said:
So a PCIII and a 3,5 bar FPR gives a snappier throttle response.
I am wondering if a 3,5 bar pump + a 3,5 FPR on my stock 1100GS and a CO2 potentiometer adjustment would do the same thing.

The point is that getting a custom map on a PC111 after fitting the 3.5bar FPR (as I did on my 1100S) provides a map that takes account of the increased pressure. You get to make use of it but in a controlled way. More fuel generally gives a snappier throttle response but only within reason and just chucking more in by increasing the fuel pressure without any mapping change is....well....a lottery.

If you fit one without a lambda sensor (your CO2 pot won't 'sense' the fuelling and adjust to suit) then the bike will tend to run rich all the time. If you have mods like a free-flowing exhaust and air filter then perhaps the mixture will be near to OK but it's unlikely to be spot on under all conditions.

By all means try it, but I'd want to put the bike on a dyno to see what the effects were.

blues_bleu · Nov 26, 2009

how about getting a higher capacity pump??
will it work better??

MattW · Nov 26, 2009

blues_bleu said:
how about getting a higher capacity pump??
will it work better??

I would have thought a higher capacity (i.e higher flow) pump would just end up recirculating more fuel around the tank - once you've supplied enough to meet the pressure / flow requirements of the injector manifold, the rest is just wasted energy :nenau

dancata · Nov 26, 2009

blues_bleu said:
how about getting a higher capacity pump??
will it work better??

by higher capacity you mean more liters/hour? it will not work better, it will just work ok.

as an update, the Renault Dacia Logan pump that I am using right now has a 80l/hour capacity unlike the OEM one, that has 110l/h. because of that, I can't wheelie my bike no more using just the gas, I have to use the clutch too, but that's ok cause' I didn't got the bike for wheelies!

So it works just like the OEM one just it won't wheelie anymore.

Using a higher pressure pump might just breake the FPR I think...

dancata · Nov 26, 2009

MattW said:
I would have thought a higher capacity (i.e higher flow) pump would just end up recirculating more fuel around the tank - once you've supplied enough to meet the pressure / flow requirements of the injector manifold, the rest is just wasted energy

that's right!

Fuel pump alternative replacement

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