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1Back to top Go down   Faulty Fuel pressure regulator Empty Faulty Fuel pressure regulator on Fri Sep 11, 2020 2:21 pm

warmshed

warmshed
active member
active member
Has anyone has a faulty fuel ressure regulator, my K1 is running rough , measured the fuel pressure and the pressure reading is jumping around but the average of the swing seems to be around 30 psi, according to the books this should be 36 psi. What are your thought or experiences of this?  Many thanks.

    

2Back to top Go down   Faulty Fuel pressure regulator Empty Re: Faulty Fuel pressure regulator on Fri Sep 11, 2020 3:39 pm

moriarti

moriarti
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Life time member
Have you measured on both feed and return  and got same readings


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1984 k100 rs red/black VIN  0004449
    

3Back to top Go down   Faulty Fuel pressure regulator Empty Re: Faulty Fuel pressure regulator on Sat Sep 12, 2020 5:06 am

warmshed

warmshed
active member
active member
No, I took the reading from the rear of the fuel rail and the tube to the pressure regulator. Fuel flow though the rail looks good so do not have any indication of a blockage within the rail. Thank you for your reply

    

4Back to top Go down   Faulty Fuel pressure regulator Empty Re: Faulty Fuel pressure regulator on Sat Sep 12, 2020 5:59 am

moriarti

moriarti
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My thinking was to prove,pump and internal pipes are all good before stripping the RETURN VALVE down Very Happy


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1984 k100 rs red/black VIN  0004449
    

5Back to top Go down   Faulty Fuel pressure regulator Empty Re: Faulty Fuel pressure regulator on Sat Sep 12, 2020 9:35 am

warmshed

warmshed
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active member
Yes I agree but should have added the background. I have checked to pipes inside and outside the tank all good. Vacuum pipe to FPR good too.had a new pump and filter 3 months ago. All had been good for 3000 miles of my ownership then suddenly started to run badly loss of power won't rev cleanly.Always starts on the button, no problem. As new things go wrong, fitted new Mahle filter, then a known good pump. Fitted new rubber caps on the vacuum take off pipes.
Just bought but not yet fitted a new set of plugs, original look good. Have bought a good used TPS and have a replacement FPR that I will fit last dues to it being a pain to get at. I purchased a fuel pressure gauge results as I mentioned in my first post. Really fed up that I can't use my K1. Maybe someone could throw a light on for me. Being the 16valve bike it has first generation motronic ecu.

    

6Back to top Go down   Faulty Fuel pressure regulator Empty Re: Faulty Fuel pressure regulator on Sat Sep 12, 2020 3:52 pm

MartinW

MartinW
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The return line from the FPR where it goes into the tank can crimp over especially if it is non OEM. The OEM one has the bends molded in, the non OEM relies on the quality of the hose. And even good quality hose can collapse at the bend due to hot weather. The supply hose from the tank to the rail should also be checked for crimping.
Regards Martin.


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K75s Hybrid
    

7Back to top Go down   Faulty Fuel pressure regulator Empty Re: Faulty Fuel pressure regulator on Sun Sep 13, 2020 12:03 pm

sidecar paul

sidecar paul
Life time member
Life time member
Fuel pressure regulators do wear out, here's a picture of the internals of one that failed.

Faulty Fuel pressure regulator Sam_0910

The ball should be captive behind that centre washer thingy.

Paul.


__________________________________________________
'84 K100RS (0014643) (owned since '85), 86 K100RS (0018891) with Martello sidecar (built as an outfit in '88),
'51 Vincent (since '67),'72 Montesa Cota (from new), '87 Honda RS125R NF4 (bought 2015) 
....No CARS never ever!
    

8Back to top Go down   Faulty Fuel pressure regulator Empty Re: Faulty Fuel pressure regulator on Sun Sep 13, 2020 2:29 pm

warmshed

warmshed
active member
active member
Thank you Paul, would love to find my one is faulty as I need to find the fault of my poor running.

    

9Back to top Go down   Faulty Fuel pressure regulator Empty Fpr on Sun Sep 13, 2020 6:00 pm

daveyson

daveyson
Life time member
Life time member
Remove the hose to the FPR from the rail. Connect your replacement FPR to a hose returning through the filler cap opening, as a temporary measure to see if it then runs normal.


__________________________________________________
11/1985 bmw k100rt (late model)  Vin. 0090567
    

10Back to top Go down   Faulty Fuel pressure regulator Empty Re: Faulty Fuel pressure regulator on Mon Sep 14, 2020 5:10 pm

warmshed

warmshed
active member
active member
@daveyson wrote:Remove the hose to the FPR from the rail. Connect your replacement FPR to a hose returning through the filler cap opening, as a temporary measure to see if it then runs normal.
Daveyson, what a simple way to do it. Obvious really, but would not of though to do it that way.  Cheers. thanks a lot.

    

11Back to top Go down   Faulty Fuel pressure regulator Empty Fuel pressure on Mon Sep 14, 2020 8:55 pm

daveyson

daveyson
Life time member
Life time member
OK,  good luck with it.

When you say it bounces around, if that means say 36 to 25ish, maybe the regulator is good (considering that the pressure fluctuates, and also that it doesn't exceed 36) from these forums fuel problems are often caused by the electrical plug to the tank.

After a run, unplug the vacuum hose from the throttle body, if there is fuel or moisture leaking out the vacuum hose, you don't need to do the FPR test, you just need to replace it.

Check that it is easy to blow through the filter. A new filter that has broken temporary end caps can absorb moisture from the air over time, swelling the element but probably good enough at idle.


__________________________________________________
11/1985 bmw k100rt (late model)  Vin. 0090567
    

12Back to top Go down   Faulty Fuel pressure regulator Empty fuel pressure on Tue Sep 15, 2020 1:50 am

daveyson

daveyson
Life time member
Life time member
Here's another tip that seems so obvious, but that I never would have thought of.

https://youtu.be/X9yX4wpAAbQ


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11/1985 bmw k100rt (late model)  Vin. 0090567
    

13Back to top Go down   Faulty Fuel pressure regulator Empty Re: Faulty Fuel pressure regulator on Tue Sep 15, 2020 11:02 am

Holister

Holister
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@daveyson wrote:Here's another tip that seems so obvious, but that I never would have thought of.

https://youtu.be/X9yX4wpAAbQ
Never heard of that before. Brilliant!
I might give it a try when I get the opportunity. Cheers Very Happy


I'm not familiar with the K1 but I'm pretty sure that all 4v Motronic models run at 43psi.
The earlier 2v Jetronic is 36psi.


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1989 K100RT     VIN  0097367 (naked)  
1996 K1100RS   VIN  0451808
  Faulty Fuel pressure regulator Austra12    Fuel:  95 Octane
Engine Oil: Nulon Full Synthetic 15W50
Gear Box Oil:  Nulon Synthetic 75W90
    

14Back to top Go down   Faulty Fuel pressure regulator Empty Re: Faulty Fuel pressure regulator on Tue Sep 15, 2020 12:34 pm

Laitch

Laitch
Life time member
Life time member
@Holister wrote:I'm not familiar with the K1 but I'm pretty sure that all 4v Motronic models run at 43psi.
The BMW K1/K100 4V manual indicates 2.5 bar/36.25psi.


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1995 K75 77,000 miles
Faulty Fuel pressure regulator Usa-lo10
    

15Back to top Go down   Faulty Fuel pressure regulator Empty Re: Faulty Fuel pressure regulator on Tue Sep 15, 2020 8:10 pm

warmshed

warmshed
active member
active member
Replaced the TPS with another used one still running rough. Can get the bike to rev on the road if I am very gently with the throttle opening any more than a small continual increase bogs down the engine, getting really fed up not to be getting any further with this fault. Changed the new fuel filter that was easy to blow through with another new Mahle filter, no change. Tank spotless inside. Injectors? Would this really just come on and make his engine run poorly without any blip of full power any time?

Who know any good K mechanic I can turn to? I'm down in Essex near the Dartford Crossing.

    

16Back to top Go down   Faulty Fuel pressure regulator Empty Re: Faulty Fuel pressure regulator on Tue Sep 15, 2020 8:28 pm

Point-Seven-five

Point-Seven-five
Life time member
Life time member
When  you replaced th TPS, did you set the idle position?  There is a function in the Motronic that when you ground one of the pins on the diagnostic plug lets you precisely sync the TPS to the throttle butterflies.  It's a very important setting to have a correct mixture across the range of throttle openings.


__________________________________________________
Present:
1994 K75RT
1991 K100RS
1988 K100RS SE

Past:
1994 BMW K75S
1992 BMW K100RS
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

17Back to top Go down   Faulty Fuel pressure regulator Empty Re: Faulty Fuel pressure regulator on Wed Sep 16, 2020 3:50 am

warmshed

warmshed
active member
active member
No. I checked the Clymer book for TPS replacement  and no mention of that, can you direct me to any relevant information of how to do that please.  Thank you for your reply.

    

18Back to top Go down   Faulty Fuel pressure regulator Empty Re: Faulty Fuel pressure regulator on Wed Sep 16, 2020 5:03 am

Packo

Packo
Silver member
Silver member
@warmshed wrote:No. I checked the Clymer book for TPS replacement  and no mention of that, can you direct me to any relevant information of how to do that please.  Thank you for your reply.
http://www.k11og.org/forum/viewtopic.php?t=2110&postdays=0&postorder=asc&start=0


__________________________________________________
______________
 
83 K100 HRD Outfit
77 R100RS
1992 K1100 Outfit
1983 K100
    

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