BMW K bikes (Bricks)

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1Back to top Go down    Fuel leaking from exhaust on Tue Mar 12, 2019 6:37 am

Felow

Felow
active member
active member
Trying to restore a 1989 K100RS that has been standing still for 10 years and have run into some problems on the way.

Thins I'vedone so far is:


  1. Change all the fuel lines
  2. New fuel pump and fuel filter
  3. Oil change
  4. New fuel injectors(The old ones didn'twork anymore)
  5. Cleaned the throttle body
  6. New spark plugs DPR8EA-9 ( not sure these are correct?)


Now the problem is when I start it after it has been standing still for a couple of days it backfires and then gas comes dripping out of the exhaust.
This is where I am stuck at the moment and would like some feedback.

Also, I am unsure of the spark plug wires are correct since I accidentally took them off without marking the order of them. But I have got the bike running with only using starting gas.

    

2Back to top Go down    Re: Fuel leaking from exhaust on Tue Mar 12, 2019 6:56 am

92KK 84WW Olaf

92KK 84WW Olaf
Life time member
Life time member
If yours is a 16v engine then plug with R in it is correct as it uses resistor plugs. If its a 2v then use plugs without R, they don't use resistor plugs.

I am guessing here but wonder are you getting gas pressure too high due to afaulty fuel pressure regulator. This is in between the throttle bodies and airbox on 2v engines, with a vacuum line from the end of the throttle bodies beside the coils that is routed into it. If that's cracked no vacuum, bad running and fuel pressure way too high. You also have 3 vacuum caps.....again same effect.

But standing a few days and gas coming out is also possibly suggesting an alternative of fuel leaking in.....injectors are normally the only way that happens, as in stuck open. Pull plugs before firing up and check each cylinder....should all be clear at that point.

One could ask what injectors you replaced the original ones with?


__________________________________________________
1992 K100LT 0193214 Bertha Alaska Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 58,645 now 90,575 miles
1983 K100RS 0011175 Fricka 29,000 miles Damn K Pox
    

3Back to top Go down    Re: Fuel leaking from exhaust on Tue Mar 12, 2019 7:14 am

MartinW

MartinW
Life time member
Life time member
A faulty temperature sensor or bad connection can cause over fueling. There is a procedure for testing on this site. Try starting the bike with # 6 Kraffstoppe fuse removed, you will have to manipulate the throttle. It should start but run badly and as the engine starts to die ram the fuse back in. It helps if you have two people one on the throttle and one on the fuse.

Regards Martin.


__________________________________________________
K75s Hybrid
    

4Back to top Go down    Re: Fuel leaking from exhaust on Tue Mar 12, 2019 7:27 am

Felow

Felow
active member
active member
Thanks, Olaf, my bike is an 8 valve engine so I will go and get new spark plugs.

And I have already gone over and checked for cracks but maybe have to do that again so I can rule that out.

The gas only starts leaking when I am trying to start it otherwise there is no leakage.

I got used fuel injectors from a used K100 that was in working condition.



I will try that out as well Martin!

    

5Back to top Go down    Re: Fuel leaking from exhaust on Tue Mar 12, 2019 9:24 am

duck

duck
Life time member
Life time member
D7EA is the correct plug for a 2V K100.

What Martin said about bad or poorly connected temp sensor causing overfueling.


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S (K1 front end)
14 Yamaha WR250R
http://www.ClassicKBikes.com
    

6Back to top Go down    Fuel leaking from exhaust on Tue Mar 12, 2019 10:05 am

norton71

norton71
Silver member
Silver member
Backfiring and fuel in the exhaust?
...I trust you are not twisting the throttle whilst trying to start a fuel injected bike....don't touch the throttle at all!, just hit the start button (with the fast idle/choke set on the first notch) Smile

    

7Back to top Go down    Re: Fuel leaking from exhaust on Tue Mar 12, 2019 10:13 am

duck

duck
Life time member
Life time member


__________________________________________________
Current stable:
86 Custom K100 (standard fairing, K75 Belly pan, Ceramic chromed engine covers, paralever)
K75 Frankenbrick (Paralever, K11 front end, hybrid ABS, K1100RS fairing, radial tires)
86 K75C Turbo w/ paralever
94 K1100RS
93 K1100LT (x2)
91 K1
93 K75S (K11 front end)
91 K75S (K1 front end)
14 Yamaha WR250R
http://www.ClassicKBikes.com
    

8Back to top Go down    Re: Fuel leaking from exhaust on Tue Mar 12, 2019 12:04 pm

92KK 84WW Olaf

92KK 84WW Olaf
Life time member
Life time member
Getting at the temp sensor will also tick off a few other jobs like cleaning and flushing the rad/cooling system, checking the fan, cleaning filler cap, cleaning out a few other electrical connections under the tank.......


I could have said you just need to take off the rad.....


__________________________________________________
1992 K100LT 0193214 Bertha Alaska Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 58,645 now 90,575 miles
1983 K100RS 0011175 Fricka 29,000 miles Damn K Pox
    

9Back to top Go down    Re: Fuel leaking from exhaust on Tue Mar 12, 2019 2:21 pm

Felow

Felow
active member
active member
Thanks for the help, will get back as soon as I have tried everything you have said.

    

10Back to top Go down    Re: Fuel leaking from exhaust on Tue Mar 12, 2019 2:32 pm

Two Wheels Better

Two Wheels Better
Moderator
Moderator
A local aftermarket BMW tech had a K75 in his shop recently that would piss fuel when cranking. He looked at 'everything' and was quite frustrated. Turned out to be a loose connector plug up to the AFM unit and a slightly sticking flap. Runs a charm after a bit of fiddling.


__________________________________________________

1987 K100RS, '89 K100 w/K1100RS engine, '93 Framed K11/K12 engine 'Big Block', '09 K1300GT, '07 K1200R, '95 R100 Mystic & '77 R75/7.

    

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