BMW K75 Fuel Pump Issue

[k-a-v]

I've have been offered a 1995 BMW K75LT for a resonable sum but it has on issue with it - a loud whining fuel pump (I know they all whine so some extent). The bike has to be bought with this fault.

This is a new fuel pump as the owner replaced the original four weeks ago (himself) as the previous one had similar symptons. He unfortunately did not replace any of the fuel filters (one of which he said has a tear) whilst doing so. BMW have said that the failure to replace the fuel filter has ruined the new pump and another is required.

Any thoughts? Does this sound right? Could it actually be another problem not the fuel pump? I want to purchase this bike to ride through the Middle East back to the UK and would like something that isn't going to need continual repair. I also have an R80G/S bought for the journey but it is unlikely that this is going to be in a reliable condition in time so this is the next choice.

Thank you.

[MotoEdde]

If the pump is 4 weeks old and is whining...you're fine. Make sure you get the paperwork to prove that BEFORE he sells you the bike.

If you choose to buy the bike, ask for the old pump as well as promptly replace the filter. Also ask the previous owner what other work he personally has done to the bike...and make sure you check it...or post it on here. The final drives splines...if not properly greases...are a weak point on that bike.

Anyways...filters are cheap...you don't necessarily need the BMW specific one...here are some alternative choices...

Triumph Stock - T1240850
AC GF61
BMW - 16 14 2 325 859
Fleetguard FF149
Fram G2
KNECHT MAHLE KL145
Motocraft FG-2
Napa Gold 3032
Purolator - F20011
Wix 33032

[k-a-v]

MotoEdde, thanks for the quick reply. I have seen the receipt for the pump so pretty sure it has been replaced as he said. Good point about seeing the old fuel pump.

Yes done a fair bit of internet research on the bike so know of the spline issue (though owner doesn't). The bike has apparently a full service history (and only 25k km) but I will check this with the BMW service centre here.

Could you just explain why you think the pump is fine please. The noise the pump makes is so loud as not to be normal. Can a clogged/damaged fuel filter really cause (a new) pump to make so much noise?

Thanks

[MotoEdde]

You have to understand the circuit your fuel travels...

Fuel flows from within the tank into the fuel pump via a pre-filter attached to the bottom of the fuel pump and then pushed through the fuel filter into the fuel rail. From the fuel rail, the necessary fuel then flows into the injectors and the remainder returns to the tank via the fuel pressure regulator and the pump cycle begins again.

Since the pump is a Positive Displacement type, it pumps at a constant rate no matter what, and the fuel pressure regulator returns the excess fuel back into the tank. You have filter before the fuel pump, one after the fuel pump, and one inside the fuel injectors.

Considering the bike is running...and its been only four weeks...the MOST important question would be...how many miles did he put on the new pump? And did he bother to replace the rubber mount/vibration dampener the pump sits on inside the tank?
If he didn't...then the rubber dampener the fuel pump sits on could have deteriorated and got sucked into the fuel pump. THAT my friend would be my biggest worry...

Inside a K75 fuel tank...
Search results for k75 fuel-filter

Part #3 and #4 in the picture below is the fuel pump mount and vibration dampener...check and see if these BMW part numbers are on the receipt when he purchased the fuel pump...OR when these were last replaced. If these are original...their deterioration is probably caused the original fuel pump/filter to get clogged...and is causing the new one to as well.

[url=http://www.realoem.com/bmw/showparts.do?model=0572&mospid=47908&btnr=16_0243& hg=16&fg=05]RealOEM.com]RealOEM.com

[k-a-v]

Many thanks MotoEdde for the reply. Only briefly looked at the receipt, but pretty sure it was only for the fuel pump. He has openly admitted to not replacing the two fuel filters so expect the damper will not have been replaced either.

I don't mind replacing the furl pump with a third if need be (the purchase price of the bike reflects this). What I am more concerned with is that the whine is symptomatic of greater problems I only uncover when trying to get it fixed (knackered injectors or something).

Mileage on new pump is negligible he has only done 700km on the bike in the year he owned it (he also owns two other bikes).

Can't see the flickr photos at the moment (site banned in UAE) so willl have a look at home through the V*N this evening. Once again thanks for the advice from your website looks like your K75 has been well used.

[MotoEdde]

Worth the double check. As far as your concern of the fuel pump noise being a leading indicator to bigger issues...I would say the following.

I think you're lucky that the guy hadn't bothered changing the filter...as it probably helped save the fuel injectors from getting clogged. Remember the fuel flow circuit! So I don't think you'd have to worry much about the fuel pump IF its 4 weeks old AND that rubber dampener/mount is replaced in a timely fashion.

The concerns you may want to have is of any prior work done by this owner...as he clearly isn't a decent enough mechanic despite his valiant efforts. Find out what work he's done prior including local shops.

With the K75 bikes...the best thing you can do for these bikes is ride them...

[k-a-v]

Seeing the owner again for the last peek. Will see what other work he has done as you suggest. Good news is that the lastservice was by BMW.

Cheers

[Stewart H]

Dirty filters will make the pump noisy, some bikes run around like that for thousands of miles, there are resourceful folks out there running automotive fuel pumps too, injectors can be serviced/cleaned for around £20 each, this bike sounds like it needs filters and the rubber damper changing.
Stewart

[k-a-v]

Had a test ride today. The owner had been out and rode it to have it tested and said it ran perfectly. I took it out and spluttered under hard acceleration. Owner said 'may be low on petrol', so off we road to the filling station. Didn't get there the K75 stalled - zip in the tank. So off I went to get the go go juice.

45mins later test ride 2 with now a full tank, guess what? No fuel pump noise. It looks like in replacing the second filter (this time by BMW) the low fuel light had become disconnected/damaged/out of adjustment.

Bike ran perfectly to my untrained eye, no jerkiness under acceleration or gear change. Live in Dubai so the heat on the legs puts me off a little, I rode it on a fairly cool night and was surprised at how hot my legs were. Might be an issue here on a hot day.

Found the bike incredibly easy to ride/get on-off stand and loved the gear display.

Two dislikes about the bike:
- felt unstable beyond 70mph. I put this down to crappy tyres old and not a known reputable brand.
- felt vibey at 70mph and above, I was surprised at this given the legendary smoothness, I was doing 5000rpm ay 80mph (I think).

Any thoughts on the above two issues? Also where would you find the tool kit on the bike, the owner didn't know.

Thanks

[MotoEdde]

No gas??? Now that could create a fuel issue

Anyways, glad to read it may be a non-issue...BUT I would still check the fuel filter and the rubber dampener. Once that dampener starts to go...your pump will soon be dead.


Re: your vibration issue, I would check the following:

1. Tire pressure...should be about 29 PSI in the front and 32-34 in the rear...cold...before you ride. I'm 6'3" and weigh about 190lbs. Depending on your size and weight you could adjust the above recommendation.

2. Also, fork oil and when it was last changed. Should be changed every 1-2 years. 10 weight oil is fine.

3. Rear shock? Is set up properly?

Part of the reason I don't think its the motor necessarily is that the vibration would occur at similar RPMs no matter what your MPH is.

HTH

[heavens angel]

K A V

Hi,

I am a British expat teacher based in kuwait and have an almost mint (only 1 small front fairing scratch) 1991 Black K75RT with full touring equipment. It has less than 9,000 km from new and runs PERFECTLY.
I found it last year, two weeks after I bought a brand new R1200GSA for my RTW trip.
The original 70+ yr old british expat bought it new in 1991 and only put 5,800 KM on it in 18 years. When I bought it last year, it still had the original tyres on it. It has full BMW service history from new. Last serviced at about 6,000 km when BMW replaced the tyres, new battery, and changed all the fluids (inc brake, clutch fliud, coolant etc). I have a new pair of front fog lights and additional twin rear LED stop lights mounted on the two panniers. Also new Sony CD player and speakers fitted.

Beween my R1200GSA, K75RT, 328 convertible and V8 Jeep Grand Cherokhee, I don't use the bike as much as I ought to and thus would like to find an apprecitive new homw for it. Otherwise I'll probably ship it back to the UK to use in summer.

If you are interested then let me know and I'll pass on my email and Tel details.

Sorry if it seems that I've hijacked your thread, just thought this might be of interest or help to you.

regards
H A

[heavens angel]

H A V

Also new fork oil in front shocks, and new rear shock fitted in Sept'09.
Other work also probably completed but i can't recall them now. Have all the bills to prove.

regards
H A

[k-a-v]

H A thanks for the reply. A tentative interest at the moment (but thats how I ended up with my G/S). Perhaps you can send some photos to my email address: xxxxxxx with the price you are looking for.

The logistics may be a bit difficult in getting a bike from Kuwait to Dubai, I'm not sure. On advice of others in the UAE I had almost decided to import one from UK as this has paperwork advantages in riding it home, but lets see where this one goes.

Cheers

Billy

[MotoEdde]

Also just posting this for future reference.

If you need a fuel pump and have no interest in paying the exorbitant BMW price, you can use one from a 1993 VW Fox...the pump is almost identical, except for the electrical connector, which you'll have to modify. Very easy though.

[k-a-v]

H A, was an interesting offer re your K75 but had no reply to my pm sent. Didn't want to leave my email address on the post so deleted it but you have it in the pm.

So I'm still on the lookout for a bike and if you want to get in touch please do. Otherwise safe riding.

Billy