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Discussion Starter #1
Hey all thanks for input in advance. I was riding home today 20 mi. at 60-75mph. on my 93-k75.
Just replaced clutch cable, adjusted to spec. 600miles ago.

Approaching a stop it started to stall, heard knocking, I clutched and it stalled. Started up and got another block, similar thing. I noticed once i popped into 2nd it ran smoother than in 1st. When I clutched, knocking began and stalled, clutch is engaging fine. but issue is now it won't start.

Pump pumps fine when disconnected (at tank), and return line is spewing gas when disconnected (at tank) and I press start button. Fuel flows from and back into tank. Have good power, engine cranks but won't start.

Weird thing, couldn't start it to relieve fuel line pressure, so just disconnected lines.
I noticed the bike starts up easily with the fuel line disconnected from rail (at the tank) and will run until it runs out of fuel in the rail.. . . Help, what should I be looking at? for?
 

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Have you ever replaced the fuel filter? Sounds kind of like what happens when it gets stuffed full and won't pass enough gas.

Frank
 

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Discussion Starter #3
Yes, replaced it last season after a similar incident, but now the fuel line flows when I press the starter button, its weird, the bike will start normally if the fuel pump isn't powered. I was putting things back together last night and just fooled with that, starting the bike then plugging fuel pump in before the bike stalls, and it would bog down as i plugged in pump.
 

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Discussion Starter #4
Could it be a lack of fuel causing it to stall? even though it is pumping somewhat? would that indicate need for a new fuel pump? necessary to check filter again
I renewed filter last season, after bike stalled and wouldn't run. didn't even bother checking filter when I saw gas flow from line when I disconnected it from fuel rail
 

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Discussion Starter #6
would the fuel level sender connection affect performance? or just telltale light
I'll check ignition connections, but it's odd to me bike started w/out tank, ignition issues?
 

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gullymonster said:
but it's odd to me bike started w/out tank
The injection system needs something like 30-40 psi fuel pressure to operate properly. Are you telling me that the bike runs without fuel pressure, but won't run with it?

Frank
 

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The round fuel tank power connector has given me trouble in the past. I took a pick (something very small but stiff) and used it on the female connections in the plug on the bike harness. VERY carefully try to close the gap in the connector pin, just a little more than it is. What you are trying to do is make a more positive/tighter connection when it is plugged back into the tank. Also check the wiring where it attaches to the back sides on the pins (think they are crimped) for any looseness or fraying. Unless you can verify your fuel pressure, I would replace the fuel filter. There are replacements to be had at auto parts places. 8mm/ 5/16 inlet and outlet and able to withstand higher fuel pressures.

Frank
 

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Discussion Starter #10 (Edited)
I don't have a pressure gauge in this garage, so I haven't measured pressure to or from rail yet.

I disconnected the tank from the rail without depressurizing lines (because bike wouldn't start)
After I disconnected the line from the tank, the bike started and idled off what gas was in the line above the rail.

Upon reconnecting fuel lines, I let the pump refill lines, and then disconnected WIRING to pump, the bike starts and idles, but as soon as I reconnect electric clip, the bike bogs down.


-----Went in and Picked female connections in wiring clip.------ Female side has 3 spines inside each socket, so I pushed those to make it a little bit tighter fit, checked ECU connection tight, my clymer manual is at my parents garage, im stuck working out of the hanes one, not nearly as thorough. any more thoughts?
 

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Bogs down as in flooding from too much fuel? You really need to check the fuel pressure. Them pumps are capable of well over the regulated fuel pressure required. Maybe a bad fuel pressure regulator.Or the pump could be weak from possibly overcoming a plugged filter for too long. I am keeping an eye on that on the K1200RS, second plugged filter I find in as many years, so far so good my gauge reads in specs and no weird fluctuations.

Any autoparts stores around that would rent/lend you a fuel pressure gauge? Or any kind of gauge around on some equipment/compressor??? that and some fittings, not hard to rig a gauge.
 

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Discussion Starter #12
thanks for the insight, I'll get on it now. would a vacuum leak in the system affect the pressure in the rail? I'm still trying to figure out what to look for as I'm learning how to look for it. Thanks again for your input
 

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H96669 said:
Bogs down as in flooding from too much fuel?
I had a temp sensor go bad once and it was eventually spitting fuel out the exhaust but would not fire.

Frank
 

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Discussion Starter #14
so i'm under the impression that its the fuel pressure regulator. Still need to final check the actual pressure at the rail, but all things elsewhere have cleared checks.

Anyone with experience on these going? symptoms, causes, related issues?
 

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I still have the original regulator, 29 years and 322K mi.

About the only way it can fail is if the internal spring fails or diaphragm ruptures.

Frank
 

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A bit late to look at the service manual but isn't the fuel pressure regulator vacuum operated on them? And located behind the throttle bodies so you pretty well have to remove the airbox to see anything or inspect the vacuum hose?

Sorry all I can tell you today....we spent too much time this afternoon digging out cracked vacuum lines on a big ugly Honda cruiser. :(
 

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Discussion Starter #18
alright guys, so a little update, i'm pressed for time and vehicle, so I bought the FPR, local parts store had one in stock and I took it as a sign. Had to cut the old one off the vacuum line, so that's a little shorter now, but still a little slack in it attached to the new one.
got the bike started, but now I can't open up the throttle.

checked that the lines were tight (fuel return and vacuum lines)

I reopened airbox and checked connection to the air meter, that should be on tight, and checked hose to plenum. Fuse 6, ECU connection

What did I knock out of whack/ forget to tighten up?
 

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Interesting....I saw your other thread.Now bogging.

Just for now I'll say it's a start..... :clap:

Others are having similar problems right now on the K1200 side of things. And I am having problems with the cold start up on my own bike.

The signs....for now that we have isolated some other probable causes it still points to fuel supply. You really will have to look in the tank for a cracked hose or plugged again fuel filter. I am not joking on the fuel filter, even if you think it is new all it takes is one bad tank of gas to plug it.And I have been there on the K100RS. :( And bad for the fuel pump trying to overcome the plugged filter, stresses the little motor.

I'll follow up today with the other one bogging there may be more clues there. In the meantime I will be in the shop this morning with the fuel pressure gauge attached if just to see what's up with fuel pressure, I am hoping not but may be a weakened fuel pump from twice finding plugged filters on my bike. :(

Post the part number for the FPR and source/brand. Generics always cheaper than BMW and if they have the same rating may help someone else later on. I put all them numbers in my black book.

Vacuum losses are also a probable. But not on my bike I connect the single gauge to each port in turn every year if just to doublecheck my intake manifolds repairs from a few years back. Steady readings on the gauge always. And the same with my 4-columns gauge.

You may be able to get somewhere in tracking vacuum losses by spraying flammables around the hoses/intakes. I don't like that method, on some bikes it is too hard to get behind the throttle bodies/manifolds so I'd rather rely on gauges. And depending on the flammables used some may contain chemicals that may pollute the O2 sensor if so equipped.If and only if I do the quick "flammable" checks I use an unlit propane torch, doesn't leave a messy residue or in the case of brake/carb cleaners that I sometimes see recommended won't eat the plastics or wire casings. :(

And like all flammables used in/around running engines, keep the fire extinguisher handy.

Bloody Honda from 2 days ago....bogging like crazy. We spent too long digging that cracked vacuum hose out of it. Then fresh fuel and still bogging. :(

Good Luck!
 

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Discussion Starter #20
So many fun times to be had on this bike . . .er. . .I mean TOOLING on this bike. I was wrestling with these issues, trying to check stuff and just screwing up more things.

last attempt to start bike did not go well, I had jump pack on because battery was getting low, and couldn't rev engine up at all because it cuts out with throttle.
BUT- on last attempt heard loud crackish sound from starter/bendix gear area, then a funny thing happened; I took out the key and gave up, but 2 seconds later, the engine turned over. . . and 2 seconds later . . .it turned over again, w/out key in ignition. I freaked out, went to disconnect battery and got spark at battery terminal then puff of smoke from relay box.

I'm getting ready to go back and start checking things. any suggestions on where to look, and how to test? beemer mechanic said something about starter solenoid welding a connection on low battery start, but I can't find anything in manuals about starter solenoid, and nothing about testing starter relay. But I gotta be able to start this thing so I can try and address the PREVIOUS issue that manifested, after the issue PRIOR to that. Just to recap
(stall and no start w/ fuel pump connected)---replaced FPR which lead to
(start and idle, but stall upon throttle opening)
 
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