dam thing will not run smoothly

[motojohn]

Hi I have a 2001 1150 gs that i bought a while ago with some small running problems .the throttle bodies were worn causing the butterfly's to vibrate and flutter on tick over , found some good ones changed them and all was fine , took it out for a test run and it kept surging and now and then when you open the throttle nothing happened , almost like fuel starvation then you do it again and it was fine ?
so one minuet you open the throttle and it goes like a scalded cat and then nothing , i thought it was sucking air due to the fuel being low or fuel pump blocked .
got it home and replaced the fuel pump and fixed the fuel gauge at the same time filled it up and it was fine , until i took it out again for a run and the same problem .???
i have changed the fuel pump all the cables the throttle bodies , the only thing i have not changed is the injectors although im not sure if i fitted the old ones or the ones that came with the throttle bodies , is there any way you can test the injectors ? or do i have to get new ones
thank you for any help you can give

 

[oblertone]

You've had the tank off, therefore first things first. Check the positioning of the throttle cables by your right knee.

 

[motojohn]

no the cables are fine and are seated , its a massive flat spot every now and then like you are sucking air and not fuel

 

[DrFarkoff]

no the cables are fine and are seated , its a massive flat spot every now and then like you are sucking air and not fuel

Possibly Throttle position sensor Either the initial setting

Or possibly the variable resistance has scores or burnt tracks

Try checking the setting of it and or if you have a good used spare ?

AND one other thing

Unplug the O2 sensor

Just unplug it and go for a run? Its an old 4 wire design with a heater circuit I don't think the ECUs are clever enough to log a open circuit fault

Unplugging it just sets the ECU to a Default fuel map If its not working correctly the ecu expects voltage changes which will not be the correct information

one other thing is fuel pressure these work on timed openings at a certain pressure

If the fuel pressure is too low it wont be getting the fuel it needs to meter the correct volume

Did you check the U bend at the fuel filter for a split while you had it out ??

If you squeeze the upper rubber pipe where it heads from the plastic fuel "manifold" back to the tank But not completely shut as you could blow it off in there!

You should hear the pump groan a little , if you have a low fuel level open the fuel cap and listen with the cap open if you hear an increase in a spraying sound as you squeeze the pipe you likely have a split pipe in there "IF" the bike happens to run better (Idle smoother) it may be the fuel pressure regulator is stuck with dirt

I went through all this with a bike for someone a while back and once I had double checked all of his work in case the issue lay in there and discovered a bad fuel pressure regulator Which once changed transformed the bike

 

[motojohn]

Thanks i will give that a try i have just shelled out on a pair of new injectors to see if that has fixed it , the bike came with a standard exhaust and can that was fitted by that last owner as he said i had a remus can and exhaust on it when he got it but did not like the noise , i found one and refitted it and the bike appeared to run a lot smoother and start easier but with the flat spot still , you can give it a handful and it will open up till it red lines then do it again and nothing at all almost like the fuel is cut off .
i did see a vid on you tube with this polish guy explaining how to reset the throttle position sensor but he lost me im afraid

 

[motojohn]

is the fuel pressure regulator the round part in the fuel line under the tank ? i have had a look on ebay and can only find used ones , still looking for a new one

 

[DrFarkoff]

Just stop what you are doing

Cancel the injectors

and do one stage at a time !!

 

[DrFarkoff]

TPS setting is easy "BUT" you do need an accurate multimeter I had one that had gone out of whack and was showing batteries at 17 volts !

The rear most wire on the TPS plug is what you want to link into

Do not pierce the wire! Slip the rubber boot back and lower the connection off the TPS with a pin get a paperclip and push it up from below and refit

Use the positive crocodile clip on the paperclip and get a GOOD ground for the negative (I prefer battery negative)

Crocodile clip type wires are much better for this as it leaves your hands free

Switch on the multimeter and go for 20V DC

Switch on the ignition and you are looking for 0.38 volts "ish" (Definitely no lower than 0.37 v)

If you have 0.37 to 0.39 V Leave it alone

If not? Slacken the two small bolts and adjust in small increments slackening the screws and then VERY gently nipping them again will allow you to tap with the screwdriver handle to move it a small bit without it flying from one end of the scale to the other I think its anti clockwise to increase and clockwise to decrease value

Set it to 0.38~0.39 and gently nip the screws the rest of the way if you rotate and return the throttle it should go back to your value

Remove the clips and a bit of rubber grease on the boot and refit it and that bit is done

 

[DrFarkoff]

is the fuel pressure regulator the round part in the fuel line under the tank ? i have had a look on ebay and can only find used ones , still looking for a new one

Do all the steps first John Before you buy more bits

Diagnose first! Throwing parts at it just costs you money and isn't guaranteed to fix it

The FPR is the silver part in the middle of the Fuel line plastic manifold under the battery / ABS tray

Its held in with a big circlip

 

[hops]

is the fuel pressure regulator the round part in the fuel line under the tank ? i have had a look on ebay and can only find used ones , still looking for a new one

Yes, you can get a new one from the likes of Motorworks, I would suspect that is less likely to be the cause. The BMW Part No. is 13531465106 but i would start with the simple things. Make sure all clamps on the airbox, throttle bodies etc are tight and thelittle rubber bungs are both present under the bodies themselves.

You mentioned changing the throttle bodies, was it showing the same fault before? Have you had them balanced?

The TPS is quite easy to set up

 

[Ian J Hartley]

One thing at a time……….

You can bypass the fuel pressure regulator by disconnecting the fuel return line to the tank.

The fuel in the line will be at maximum pressure that the pump can deliver so consider the condition of your fuel lines and clamps.

 

[motojohn]

i was thinking if the tps was out of wake it would be a constant problem and yes the problem came on one day before i changed the throttle bodies and i thought it was the fuel pump but after i thought it was a low fuel problem as the fuel gauge was not working . so then used an endoscope to look in to the tank as i was not sure of the position of the fuel pump as i remember it being a pain to re fit . and the pump looked like it was not totally submerged so i filled the tank up and ran it it and it was fine and the throttle was very responsive . then when i opened it up again it was flat and then it was fine again almost like a fuel starvation problem .

 

[Rugged Path]

Same problem with my 02 1150GSA.
Currently with an indie bmw mechanic to help sort it out. Running very rich / difficult to start / O2 sensor & plugs sooting up.
Given low priority but, 10 weeks has passed already and still not sorted.

End of the month and will collect it back for plan B.



Patria o Muerte

 

[motojohn]

my plugs were also sooty , if this was a carb bike i would say it was running rich ,

 

[DrFarkoff]

my plugs were also sooty , if this was a carb bike i would say it was running rich ,

Check the TPS! and If it is in Range and still fecking around Disconnect the lamda probe!

Two easy cost free things to do that will take half an hour!

 

[motojohn]

thanks for the info i will try it

 

[Steptoe]

i was thinking if the tps was out of wake it would be a constant problem and yes the problem came on one day before i changed the throttle bodies and i thought it was the fuel pump but after i thought it was a low fuel problem as the fuel gauge was not working . so then used an endoscope to look in to the tank as i was not sure of the position of the fuel pump as i remember it being a pain to re fit . and the pump looked like it was not totally submerged so i filled the tank up and ran it it and it was fine and the throttle was very responsive . then when i opened it up again it was flat and then it was fine again almost like a fuel starvation problem .

Your thinking is all skew whiff.. if it was injectors or fuel pressure regulator it wouldn’t be intermittent. A tps problem can be intermittent. And your description does have all the ingredients of a tps problem.

 

[Grizzly]

Hi Motojohn,

You say in your first post that you changed the throttle bodies for some good ones??
These came with injectors - did they also happen to come with the TPS still fitted? - which could mean you've fitted a TPS of unkown condition.

As others have said - take one step at a time, if you change loads of bits you could be ending up with multiple faults


Cheers.........................Grizzly

 

[MotoRevive]

I would bet my money that your TPS needs adjustment. And then balance your throttles after.

 

[motojohn]

I have just ordered a new multi meter as mine was very old ,as soon as it arrives i will do the TPS check and let you know how i got on