R1150 GS weird Fueling problem

[flstf]

Hi
Can anyone offer any advice?
1150gs twin plug 2004 25k.
The bike has a intermittent fueling problem. Ignition on fast idle fully on hit starter button bike usually starts straight off and runs fine.
Yesterday it started fine numerous times and was left to idle for 5 minutes at time it accepts throttle and is responsive.The day before it eventually started after numerous tries. This has been going on for a few days now. It's 50/50 wether the bike will start. Today was a non starter. What I can do to get it to run Is open the airbox lid give it a squirt of carb cleaner and it will fire up and run fine. So far I have had the hall effect sensors off and checked. I also hooked them up to my snap on scope and both sensor traces look fine. The fuel pump primes as soon as the ignition is turned on so the relay is OK. The pump has been taken out and all pipes are fine and the filter was recently replaced. Compression is fine and both cop coils were replaced recently. Not sure wether to try a new set of hall sensors and or a fuel pump. Very odd as once it's running it runs fine doesn't seem to be heat related. I will try test the feed to the injectors while cranking when its playing up. 

Any one come across similar?
Thanks

 

[dirtrider]

1 hour ago, flstf said:

Hi
Can anyone offer any advice?
1150gs twin plug 2004 25k.
The bike has a intermittent fueling problem. Ignition on fast idle fully on hit starter button bike usually starts straight off and runs fine.
Yesterday it started fine numerous times and was left to idle for 5 minutes at time it accepts throttle and is responsive.The day before it eventually started after numerous tries. This has been going on for a few days now. It's 50/50 wether the bike will start. Today was a non starter. What I can do to get it to run Is open the airbox lid give it a squirt of carb cleaner and it will fire up and run fine. So far I have had the hall effect sensors off and checked. I also hooked them up to my snap on scope and both sensor traces look fine. The fuel pump primes as soon as the ignition is turned on so the relay is OK. The pump has been taken out and all pipes are fine and the filter was recently replaced. Compression is fine and both cop coils were replaced recently. Not sure wether to try a new set of hall sensors and or a fuel pump. Very odd as once it's running it runs fine doesn't seem to be heat related. I will try test the feed to the injectors while cranking when its playing up. 

Morning  flstf

 

Have you tried holding the twist grip about 1/8-1/4 throttle for starting on the times it won't start. This at times can really help cold engien starting. 

 

I have seen similar before, most times it is some water in the gasoline that settles during parking then gets picked up by the fuel pump as more water than gasoline. Then,  once (IF) it starts  the water gets re-mixed into the gasoline & they will run OK again until next overnight parking. (did you put new gasoline in when you inspected the pump or just re-use the old gasoline?)

 

If no water in the fuel tank then maybe try running a fuel return fuel flow test (see if any fuel is coming out of the fuel return hose coming from the rear). It takes a pretty good shot of fuel to get these things running when cold so low fuel pressure at starting can cause hard starting. If you are getting return fuel flow that means that you are getting enough fuel flow at enough pressure to open the return flow valve. If no fuel return flow then you are NOT getting enough fuel flow at enough pressure to fuel correctly. 

 

Have you monitored the battery or system voltage during cold cranking?  If the system voltage drops to much below 10v during cold cranking there isn't enough system voltage for the fueling control to operate properly so you can get a weak (or no) fuel injector spray at cold cranking. 

 

One more thought-- Are you running any sort of aftermarket fuel controller like a Techlusion or other  aftermarket fueling device? Sometimes those can really effect engine starting if they are starting to fail so if you have anything like that COMPLETLY disconnect it to see  if that effect the starting.  

[flstf]

Hi

Thanks for the reply

Tried the throttle at various positions and it doesn't help. I did check for water and or diesel in the fuel. When cranking i had the bikes battery connected up to a second supply and pulled the headlight fuses, its a new battery. I am in the process of making up some lines so i can put a fuel  pressure gauge in line.I have had the hall sensors off again and stripped the wires sleaving back to check for damage, the wires look fine. The mad thing as i said earlier is if it wont start and i give it a whiff of carb cleaner it runs. On a good day it will start and run repeatedly with fast idle on or just a bit of throttle and run fine. Its so intermittent.

Forgot to mention that the owner had it in elsewhere and it came to me with a pair of new cops fitted and when i initially tested it it  kept losing the spark. The only thing the spark and fuel have in common is the hall sensors and ecu. I hate part swapping but maybe its time to try a pair of hall sensors.