dirt getting into fuel injectors

[dfnton]

my 2 valve K100 has been having a problem with dirt getting into the fuel injectors and causing the motor to lose all power. the motor won't completely die and after some coaxing with the throttle the injector(s) clear and it will run fine for as much as 150 miles. I believe the problem started with the fuel rail, which I changed with a new one, putting a lot of rust and varnish into the fuel tank by way of the return line. I have cleaned the fuel tank twice now and can't see any debris to speak of. Have also flushed the fuel rail after cleaning the tank. Installed a new fuel filter after the second tank cleaning. Does anyone know if the fuel filter will allow large enough particles to get through it and plug an injector? Or is it another possible problem with the same symtoms? Getting frustrated and could use a little help. thanks.
Dave

[jdiaz]

I thought the BMW fuel filter had super-fine media in it....down to a couple of microns? Seems like it would pick anything up.

[dfnton]

brand new from bmw dealer for $23.81, I was hoping it would pickup anything. So how is junk getting into the fuel rail?:dunno

[mrich12000]

READ THE POST IN THIS K:bolt :drink :stick FORUMREGARDING FUEL INJECTORS AND THERE REPLACEMENT,

[dfnton]

checked on the cost of cleaning the injectors locally and as said the charge was $20 apiece. just for the heck of it, went to the Beemerboneyard website and found a set of 4 FIvalves reconditioned and tested with 'o' rings included for just a little more money than the cleaning would cost. will install these later this week and post here how things work out.:bolt

[mrich12000]

:thumb :bolt

[breyfogle]

my 2 valve K100 has been having a problem with dirt getting into the fuel injectors and causing the motor to lose all power.....Dave☺

How is it that you figured out that dirt was getting into the injectors and then, somehow, cleaning itself out ? Seems unlikely, IMHO.

[Gilly]

It almost has to be "post pump" as the pump has the screen installed (depending on the year, it would be either like a sink strainer around the base of the pump, or later bikes had a "fuel sock" similar to most cars, on the base of the pump inlet.

Now I would question if either one of these screens are there, or if someone in the past had it apart and decided it's not that important. Mainly it's there to protect the pump itself.

If it's not there, then I wonder if the rubber fuel damper is falling apart, as mine was last year, and this is the "dirt". I had some of this in my tank and it does behave alot like dirt, not hard rubber chunks like you'd expect, but behaves alot like a clot of grease. End result is a plugged up injector.

Or maybe the bike the rail came out of (assuming a used rail?) was missing the screen and filter?
Gilly

[dfnton]

☺

How is it that you figured out that dirt was getting into the injectors and then, somehow, cleaning itself out ? Seems unlikely, IMHO.

The fuel rail had alot of varnish and rust buildup in it which was released into the fuel tank after running some fuel injection cleaner. Had to dump the gas and clean the tank twice to remove all of the debris. The way the motor would run again after some coaxing had led me to believe the injector(s) had cleared itself and that dirt was the problem. After cleaning the fuel system , replacing the fuel filter ,the fuel rail, and 'o'rings and it happened again (after 120 miles of excellent running) I came to the conclusion that something else is causing this problem. Replacing the FI valves seemed like the next step. Also, it is relatively inexpensive and not very hard to do.

[BuddingGeezer]

I just finished cleaning the fuel injectors on my K75. The injectors would barely spit fuel at 36 psi fuel pressure.

I used a small hypodermic syringe to inject Berryman B12 Chemtool/ opened injector with a 9volt battery or small 12 volt battery charger. Sprayed carb cleaner through with injector opened. I then had a friend mill a piece of round aluminum bar and drill it hollow, threaded an air chuck in one end, a six inch piece of 5/8 garden hose and 1/2 hose on the other. Placed the injector on the other end of the hose. Filled with cleaner/hooked chuck to air hose @ 34psi/opened injector and flushed forward and backward. Bingo-clean injectors with good conical spray pattern. Cost+$0000

Ralph Sims

[dfnton]

Nice! :bikes

[Kayseventyfive]

All of this points to the advantages of regular use of a good fuel cleaner. My own fave is Red Line. A fellow rider whose opinions I value swears by Seafoam.

[dfnton]

Installed the 4 reconditioned FI valves I purchased from Beemerboneyard today, took about an hour. First five miles ran a little rough then started to settle out. At the end of 25 miles there is a noticeable increase in power and responsiveness. :thumb Time will tell if this corrects the problem with it dying out, but in the meantime I'm having fun! Thanks to all. Gotta love the K-bikes.
Dave
'86 K100RS
'96 R11RT