BMW K bikes (Bricks)

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TSBT


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Figured I'd start a new thread as it's been 10 months since my previous no fuel issue, back then we narrowed it down to a bad Fuel Pump Regulator. It was a bit of an ordeal and you guys were really helping coach it through, fast forward a year later.

I installed a new FPR and the starter is going and going, but I learn there is no fuel getting to the injectors. Last fall I tested the pump and it was working and there was good pressure, so what gives!?

So I tested for spark, that's good. Unplugged the fuel lines, no pressure was in them and no gas. So I started unhooking all the fuel lines to see if there was a blockage, they're all clear. So I tested all the fuses again, all good. Tested the plug to the tank, and it's getting power.

So why would a fuel pump work and then not work. Or is it something else? It's like I solve one problem, and I'm back solving the same problem again. I just want to ride, I'm sick of wrenchin, and it's like I'm Bill Murray in Groundhog Day! Thoughts?


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RicK G

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Remove the pump and run it backwards it may have a very small particle stopping it turning.
An 8micron particle can seize a rotor cell pump. If reversing it works renew the pre pump filter and try it again


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If everything seems under control then you aint goin fast enough:- Mario Andretti
Bikes 1986 K100RT, 1993 K1100 LT, 1994 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 & 1976 SR 500 Yamaha for now
    

duck

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Can you hear the fuel pump whirring when you press the starter button? Sometimes the issue is in the connections in the baseplate of the fuel level sender. I'd try bypassing the fuel level sender and jumping 12V directly to the fuel pump. Hook some other wires up to it in then then apply 12V to them. Probably a good idea to avoid causing sparks around gas fumes while doing this.


__________________________________________________
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
14 Yamaha WR250R
http://www.ClassicKBikes.com
    

RicK G

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Probably a good idea to avoid causing sparks around gas fumes while doing this.

+1 There's no roadside assist on the highway to heaven.


__________________________________________________
If everything seems under control then you aint goin fast enough:- Mario Andretti
Bikes 1986 K100RT, 1993 K1100 LT, 1994 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 & 1976 SR 500 Yamaha for now
    

charlie99

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we have seen that fuel pump connection (below the tank on the right hand side and under the side cover ) become lossy ....ie the connections become faulty ..sometimes the socket part spreads or becomes corroded ...many have crimped the socket part slightly to provide a better connection to the pump inside the tank ...
perhaps this is a contributing issue ...and no where near a rare event
all the usual suggestions apply ...clean both sides of the connector with a good cleaning agent ...and not talking about anything with ammonia or similar ...look up "deoxit" a friendly substance for such jobs

also do the fuse carriers and fuses ,,whilst your there

these connections are old on all the bikes and a slight bit of intermittency can promote carboning up of the connections

so a bit of regular maintenance is always a plus

cheers !


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cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%O
    

RicK G

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When you say you tested the fuses did you use a meter. We have see a few recently that have gone open circuit due to age and still look good.

Owning a K that is 20 odd years old does sometimes become a PITA but think of the pain in the wallet if you buy a new bike.

The fuel pump should turn on when you turn the key on and run for 1.5 seconds being a 16v engine. (Duck was referring to the 8v engines) If that doesn't happen then you need to fix that without going further and the first place to look is that mongrel connector Charlie is telling you about. Mine gave me so much grief that I went to the auto store and bought a new 4 pin connector and replaced the plug and socket (it doesn't have to look the same, a white one with the flat spade type push in connectors are fine) and its been bliss now for 2 years with regards to that. The bliss has not extended to many other places.


__________________________________________________
If everything seems under control then you aint goin fast enough:- Mario Andretti
Bikes 1986 K100RT, 1993 K1100 LT, 1994 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 & 1976 SR 500 Yamaha for now
    

robmack

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Is the fuel filter new? A blocked filter could prevent the flow of gas.


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Robert
1987 K75 @k75retro.blogspot.ca
2011 Moto Guzzi V7 Racer
http://k75retro.blogspot.ca/
    

k75RT Keith

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+1 on the fuel filter. IIWM, I'd pull the flapper, and turn the key to determine if the fuel pump is pressurizing the system. then replace the fuel filter and inspect the strainer on the pickup.

    

9Back to top Go down    PUMP UPDATE on Tue May 06, 2014 12:52 pm

TSBT


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Thanks for all the suggestions really appreciate it. This morning I replaced the fuel filter, then checked the basket on the fuel pump, no goop inside. So I checked the lines to see if there were any obstructions, they're good. Then I unhooked the tank like I did before, ran power direct from the battery to the input connector, and I didn't blow up so I knew that was a good sign, and also the pump started.

So I reversed polarity for posterity, and tried it again and it would not go, so I repeated the process and it started going again. Guess I got rid of whatever crap was in there. Then I plugged in the FPR and a fuel pressure gauge. When I turned the pump on again there was no gas coming out the brand new FPR, first with 50lbs then even 100lbs of pressure - I ran it longer so see if I was imagining it. Guys, am I missing something? Isn't there supposed to be a bit of gas coming out of the FPR? Here's my setup:



I have a backup fuel pump that I would need to MacGyver with some extra rubber to fit into the BMW sleeve. It's a Facet-Purolator FEP 20-82, cheaper alternative for all K Bikes. Anyway it's on standby if this thing is pooched. Thanks again.



Last edited by TSBT on Tue Sep 22, 2015 6:21 pm; edited 1 time in total


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Chris
    

charlie99

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sounds like that could be a real show stopper


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cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%O
    

TSBT


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@charlie99 wrote:sounds like that could be a real show stopper

Can you elaborate?


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Chris
    

robmack

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TSBT,

It's not obvious to me from the photo above but, in your test setup, which direction are you expecting the gas to flow? Is it from the tank, past the pressure gauge, into the FPR and out towards the red gas can?


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Robert
1987 K75 @k75retro.blogspot.ca
2011 Moto Guzzi V7 Racer
http://k75retro.blogspot.ca/
    

duck

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What do you mean gas coming out of the FPR?

Here's the direction of flow: Pump->Filter->Fuel Rail->FPR->Back To Tank

So, yes, if the line from the FPR to the tank is disconnected that should have fuel coming out of it if the fuel system is working properly.


__________________________________________________
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
14 Yamaha WR250R
http://www.ClassicKBikes.com
    

TSBT


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@duck wrote:Here's the direction of flow: Pump->Filter->Fuel Rail->FPR->Back To Tank

Okay I must be high on gas fumes, confirm my logic: of the two lines coming out of the gas tank, the first one (towards the front of the tank) is the return which takes the line from the FPR. The second line sends gas to the fuel rail. Something tells me I may have had the two mixed up, in which case you have solved my dilemma! and I am clearly still high from two days of high octane fumes


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Chris
    

TSBT


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@robmack wrote:which direction are you expecting the gas to flow? Is it from the tank, past the pressure gauge, into the FPR and out towards the red gas can?
I think I mixed up the fuel lines where they go into the tank, as per Duck's description of fuelflow: gas pumps directlyinto the rear ofthe fuel rail, goes to the front of the fuel rail where the hose takes it to the FPR and around to the return line in the tank. I think I had the lines mixed up at the tank which is embarrassing. In which case I can't wait to put it back together and start it up!


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Chris
    

duck

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Rear pipe to fuel rail, front to FPR


__________________________________________________
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
14 Yamaha WR250R
http://www.ClassicKBikes.com
    

TSBT


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@duck wrote:Rear pipe to fuel rail, front to FPR

Thanks Duck. I'll have a ceremonial large beer in your honour later if she starts.


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Chris
    

TSBT


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As much as I want to say I'm having a beer it didn't start, the pump didn't run. I'm thinking the problem has to be the Fuel Sender Relay, once I find it. When I checked the plug to the tank earlier however I was getting power which is weird...I'm not sure.

I'll add I took Charlie99s suggestion and cleaned the connector, also wiggled it a bunch. Maybe I need a new connector. The whole thing is fishy,


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Chris
    

Inge K.

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@TSBT wrote:I'm thinking the problem has to be the Fuel Sender Relay, once I find it.



Have you checked your sidestand switch? If the sidestand is down, or you got a malfunctioning switch......it would prevent the fuel pump to run.


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Inge K.
K100RS -86. (first owner), K1100LTSE -94.
    

duck

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First check if you side stand is down. LOL.

What he said. Find the connector (it comes up out of the right peg plate with the brake switch wiring), unplug it and short the connectors on the wiring harness side.

I have all of mine disabled so it usually never occurs to me as something to troubleshoot.


__________________________________________________
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
14 Yamaha WR250R
http://www.ClassicKBikes.com
    

duck

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Also, if you find that it's that side stand tang not pushing the switch all of the way in than an easy fix is to put a short piece of vacuum hose over the tang.

When I shorted the one on my LT I hooked the switch up to an idiot LED in the dash to remind if I left the side stand down. It started coming on every now and then while I was riding and that's how I fixed the intermittent switch problem. Has worked great for the last six years.


__________________________________________________
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
14 Yamaha WR250R
http://www.ClassicKBikes.com
    

22Back to top Go down    Update on Wed May 07, 2014 3:15 pm

TSBT


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Sorry guys think I posted a new topic when I should have hit reply to this thread!

Thanks for the KBIKE article always a good refresher. Fired up the multimeter and I'm getting a .53 multimeter reading off the Tank plug.



Then I tried swapping out the Fuel Pump Relay with the one next to it. Same reading. Checked all the fuses they're all getting 13.8 with the ignition on. bent the 4 prongs in the tank plug a bit, to see if I can get a better connection.

All roads are leading to, no whirrly sound from the pump unless I do a direct jump from the battery to the tank. So I guess it's a hunt for the loose connection. Still haven't clipped the two wires on the sidestand plug and tapped them together. So that could be an issue, will do that later.


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Chris
    

RicK G

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How about we ask Mr Moderator to combine them. I think that's the first time I've called him misterLaughing


__________________________________________________
If everything seems under control then you aint goin fast enough:- Mario Andretti
Bikes 1986 K100RT, 1993 K1100 LT, 1994 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 & 1976 SR 500 Yamaha for now
    

TSBT


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I had the bike on the road today, zipping around town doing a shakedown. How did I get it running? With the help of Robmack, he reached out and asked if I could use some help because we live in the same city! I was thrilled and took him up on his offer. The next day he rode over bringing his laptop, filled to the brim with schematics and his Fluke Multimeter. With this kind of ammo I was certain we were going to fix this.

We traced wires, tested plugs, fuses, relays, and we also checked the connection at the side-stand, suggested by Inge and Duck as a usual suspect, and I have to say I feel pretty stupid. I installed it with the tang in FRONT instead of behind the rotator that opens and closes the circuit.

When we discovered this we were both pretty excited, and I felt pretty stupid, it's amazing how something so dead simple got overlooked. But thanks to Robmack I've got my bike back. Cheers, you made my week!

And thanks again for everyone's help really appreciate all the suggestions I've learned a ton.

Now that the bike is running, hopefully Robmack and I can plan ride sometime, that would be fun.

Proud to say this K100 case is closed!!!roundel


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Chris
    

charlie99

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yippee !

good onya blokes ...


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%O
    

robmack

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Hi Chris,

I am glad that your bike is back on the road after too long a hiatus. I enjoyed the challenge; next one will be that cruise control. Get in touch if you want me to help.


__________________________________________________
Robert
1987 K75 @k75retro.blogspot.ca
2011 Moto Guzzi V7 Racer
http://k75retro.blogspot.ca/
    

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