Fuel Pump - K-Bikes.com - Excellence in Motion
 
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post #1 of 6 (permalink) Old Apr 6th, 2013, 8:02 pm Thread Starter
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Fuel Pump

Is it a question of "if" or "when" I will need a new fuel pump?

My 1983 K75S (11/92) is nearing 60K and I took care of all the filters and fluids after I bought it over 10K ago and it has given me excellent service.

After reading a thread on a possible fuel injection problem I was wondering if a fuel pump failure is something to plan for. I see Beemer Boneyard had a kit with a new vibration damper and screen for my pump.

Is this damper something that frequently deteriorates causing pump failure. With the crap fuel these days it would not surprise me that it is now a part to be replaced.

Good idea to replace it after all these years?

Thanks,

Nick
1993 K75S
1991 R100RT
1982 Yamaha XJ650RJ Seca
1978 R100S
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post #2 of 6 (permalink) Old Apr 7th, 2013, 4:21 pm
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Quote:
Originally Posted by stokester
Is it a question of "if" or "when" I will need a new fuel pump?

My 1983 K75S (11/92) is nearing 60K and I took care of all the filters and fluids after I bought it over 10K ago and it has given me excellent service.

After reading a thread on a possible fuel injection problem I was wondering if a fuel pump failure is something to plan for. I see Beemer Boneyard had a kit with a new vibration damper and screen for my pump.

Is this damper something that frequently deteriorates causing pump failure. With the crap fuel these days it would not surprise me that it is now a part to be replaced.

Good idea to replace it after all these years?

Thanks,
I can only tell you my experience.

I ran a 94 K75 from 94 to 2008 putting over 230,000 miles on it. I probably replaced the fuel pump once. I dont have the service records anymore. I dont remember thinking the fuel pump was an issue to worry about. So, the pump probably wont wear out from mileage before 100,000 miles.

I have run an 85 K100RS since 2000. It probably has the original pump in it. I havent replaced it. So, it has at most 110,000 miles and at least 60,000 miles on it. No problems with pump, screen, damper, holder or hose to date. That is 28 years or 12 years. So, age isnt necessarily a killer.

What about ethanol? It hasnt seemed to have greatly effected the pump set-up in the 85. None of my rubber parts have mysteriously dissolved or failed. I know the fuel cools the pump. If the ethanol results in the pump running at a higher temperature for some reason, that might shorten the pump`s life span. Have no data on that at all. If it also lubricates the pump, that might be an issue. I wouldnt think the pump cares what kind of liquid it is delivering...gas, diesel, water alcohol, etc. unless there are internal parts that will get eaten away from a particular liquid. As I said, not an issue for me so far on either mc.

Will the pump and related parts fail eventually? Sure, mileage and age will catch up. If you want to replace all of it now for peace of mind and keep the old stuff as back-ups, go for it. I take my chances. When the pump dies, it dies. Testing and swapping out a pump is relatively easy. If your karma is good, it will die close to civilization. You find a motel. Pay for a pump to be overnighted, swap it out and go on your way. Of couse, there will be much swearing and cursing when it happens, but its an inconvenience, not a life threatening event.

Last edited by 97tiger885; Apr 7th, 2013 at 4:31 pm.
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post #3 of 6 (permalink) Old Apr 7th, 2013, 5:29 pm
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Re: Ethanol

Nothing wrong with running ethanol. BMW issued a TSB (technical service bulletin) many years ago that running up to 10% ethanol is fine in K bikes.

However, ethanol-laced gas tends to draw in water from the atmosphere which limits it's "shelf life" compared to 100% gasoline. In K bikes that are left to sit with ethanol gas in the tank for several years they commonly build up a lot of water in the tank which:

1 - Turns the vibration damper into goo which can clog the fuel pump.

2 - Rusts and seizes the fuel pump guts.

3 - Corrodes the welded seams at the lower lips of the gas tank and causes leaks.


As noted, a fuel pump is a mechanical device that can eventually wear out but I would not bother replacing it until it does. Never had it happen myself but I've seen many reports of them getting very noisy prior to failure so at least you get some warning that it might be on its way out.

I periodically run some Techron Concentrate through my bikes to keep the fuel system clean.
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post #4 of 6 (permalink) Old Apr 7th, 2013, 7:10 pm Thread Starter
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Quote:
Originally Posted by FlyingDuck
Re: Ethanol

As noted, a fuel pump is a mechanical device that can eventually wear out but I would not bother replacing it until it does. Never had it happen myself but I've seen many reports of them getting very noisy prior to failure so at least you get some warning that it might be on its way out.

I periodically run some Techron Concentrate through my bikes to keep the fuel system clean.
Sounds like the stock fuel pump will last a long time with reasonable care. I'll take the Techron advice and check the damper regularly for signs of softening with a replacement kit at the ready.

This '93 K75S is my commuter mule and a great weekend ride bike. After my purchase with 47K on the clock I replaced all fluids, filters, repaired the ABS and replaced the tires with good Pirellis. It has been a smooth, dependable ride for over 10K miles and I want to keep it that way.

Thanks for the advice.

Nick
1993 K75S
1991 R100RT
1982 Yamaha XJ650RJ Seca
1978 R100S
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post #5 of 6 (permalink) Old Apr 7th, 2013, 10:59 pm
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Quote:
Originally Posted by FlyingDuck
Re: Ethanol

Nothing wrong with running ethanol. BMW issued a TSB (technical service bulletin) many years ago that running up to 10% ethanol is fine in K bikes.

However, ethanol-laced gas tends to draw in water from the atmosphere which limits it's "shelf life" compared to 100% gasoline. In K bikes that are left to sit with ethanol gas in the tank for several years they commonly build up a lot of water in the tank which:

1 - Turns the vibration damper into goo which can clog the fuel pump.m

2 - Rusts and seizes the fuel pump guts.

3 - Corrodes the welded seams at the lower lips of the gas tank and causes leaks.


As noted, a fuel pump is a mechanical device that can eventually wear out but I would not bother replacing it until it does. Never had it happen myself but I've seen many reports of them getting very noisy prior to failure so at least you get some warning that it might be on its way out.

I periodically run some Techron Concentrate through my bikes to keep the fuel system clean.
I use Techron occasionally as well for the same reason. The other thing you can do is remove and empty the tank every year. That allows you to see if you have water collecting in the tank and ensures you have removed it. A BMW tech also told me it is a good idea to clean out the tank occasionally because there can be grit suspended in the gas from gas station tanks that can make it into and collect in your tank at the lowest point. Vibrations turn this into an abrasive that can start eating away at the tank at that point. Not a huge concern, but another reason to empty the tank occasionally.
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post #6 of 6 (permalink) Old Apr 8th, 2013, 6:46 pm Thread Starter
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Quote:
Originally Posted by 97tiger885
I use Techron occasionally as well for the same reason. The other thing you can do is remove and empty the tank every year. That allows you to see if you have water collecting in the tank and ensures you have removed it. A BMW tech also told me it is a good idea to clean out the tank occasionally because there can be grit suspended in the gas from gas station tanks that can make it into and collect in your tank at the lowest point. Vibrations turn this into an abrasive that can start eating away at the tank at that point. Not a huge concern, but another reason to empty the tank occasionally.
Yup, good annual maintenance that Bob Fleischer (AKA Snowbum) recommends for regular Airhead maintenance on his site http://bmwmotorcycletech.info/ . This K75S is such a smooth-running reliable machine that I want to lead-turn any known maintenance issues or component failures. Sounds like the fuel pump is reliable but will eventually wear out so I'll keep the tank clean and check the dampers for aging.

I remember someone, FlyingDuck?, mentioning the new Bosch injectors. Anyone got good reports on them? Worth the effort/$$ on a good running machine?

Nick
1993 K75S
1991 R100RT
1982 Yamaha XJ650RJ Seca
1978 R100S
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