Misfiring 1150

gothbiker

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I've a slight problem with my 1150 gs single spark, it starts and ticks over great, it just runs out of power and misfires, I can do 65 on the flat, power drops off and misfires if I go up a incline and I'm down to 55 mph, down hill I can get to 70, k would say at 3-4K it starts miss firing,
I've given it a full service, new plugs, filters, balance throttle bodies and valve clearances, external fuel filter changed (took it out of the tank years ago) fuel injection cleaner though it with fresh fuel, throttle cables seated correctly.
What's the next thing to replace? Plug leads? Coil? Hall sensor? Or check the fuel tank pipes in the tank?


From a fuckin iphone....
 
Have you had your tank off?

sorry just seen you've considered unseated throttle cables....
 
Firstly I say Diagnose it First just don't change parts (Or if yo do Change one part at a time to see what was failed! Rather than thinking I wonder which bit did it?)

Thoughts on this one

If its getting fuel and supposedly sparking As it is running okay "but" not under load

from what I understand from your description it's running out of Oomph and farting about when Under load??

The Throttle Position sensor is a favourite!

You need a Multimeter with leads you can clip on and a pin Its the rearmost cable at the TPS connector and you jam the pin through it and clip your positive lead on and clip the meter neg lead to a bloody good earth and switch the meter to 20V DC and switch on the ignition make sure kill switch is in Run position and gearbox in Neutral

You are looking for a reading of 0.37 to 0.38 V If you can't get anywhere near that the TPS is possibly fecked and basically not telling the ECU that the throttle is open Hence not enough Fuel = No Power = uncle buckaroo

Fuel Pressure relief valve stuck slightly open so optimal fuelling is not possible is also a possibility The test is slightly worrying for you in that you have an external filter and hoses so I suggest using a fuel line clamp and NOT completely closing the return line but reducing it significantly thereby increasing fuel pressure If you have access to a fuel pressure regulator Even better Just set it to to 2 bar and fit it between the return line connection and the tank lines
 
Ref: unseated throttle links.
Not this time chaps. His bike runs fine at idle. It's the higher revs he has an issue.
 
gothbiker said:
I've a slight problem with my 1150 gs single spark, it starts and ticks over great, it just runs out of power and misfires, I can do 65 on the flat, power drops off and misfires if I go up a incline and I'm down to 55 mph, down hill I can get to 70, k would say at 3-4K it starts miss firing,
I've given it a full service, new plugs, filters, balance throttle bodies and valve clearances, external fuel filter changed (took it out of the tank years ago) fuel injection cleaner though it with fresh fuel, throttle cables seated correctly.
What's the next thing to replace? Plug leads? Coil? Hall sensor? Or check the fuel tank pipes in the tank?


From a fuckin iphone....
Click to expand...

Another possibility is that you have a split in tank hose that's leaking. Everything is fine until you have to deliver the top volume of fuel needed at higher power.

Measure the amount of fuel returning to the tank from the fuel distributor. If it is about 2 liters per minute at idle you're fine.
 
I had a similar running problems with my R1100GS. Poor compression test results led to me stripping the cylinder heads and servicing the valves. However the same poor running persisted. A number of electrical components were checked and or replaced.
In the end however the solution was, as is almost always the case, very simple indeed.
Pulling back the boots of the fuel injector connectors, I found a lot of damp. A wipe and spray of ACF50 got the bike running properly again. I then fitted shrink wrap over the wire connectors to protect them.
I would recommend you check the simple things first, unlike myself!!!!
 
thanks for all the advice, I've unplugged the fuel return line and it runs great, they tps looks fine with a multi meter, i thought it was a split pipe, I've just had the tank off, replaced the rubber pipe with a new one, and its no different!, I pulled over to unplug the fuel return pipe so i could get home, thinking now its either the fuel pump or fuel pressure regulator, hopefully i can find a garage with a fuel pressure gauge on monday so i will see what the fuel pressure is.
 
Check the resistance across the injector plug terminals. Should be around 16 ohms. Much higher, lower or a big difference between the two injector readings means that could well be your problem.

But your symptoms do sound like a TPS problem. Get someone with a GS911 to read the fault codes, a TPS problem will show up.

Could also be a Hall sensor problem. :D
 
Thanks steptoe I'm measured them both and they are both 16. Something ohms.
Do you think it beneficial to clean the injectors


From a fuckin iphone....
 
Pull the boots on the injector lead connectors and check for damp. As I said previously this can affect the running giving the symptoms you described...
 
gothbiker said:
Do you think it beneficial to clean the injectors
Click to expand...

Pull them out **CAREFULLY** see what the atomisation is like when you are spinning the bike over If its dribbling them there's something wrong if is a nice mist They are okay

Basically as long as its not like a water pistol squirt They should be okay
 
I will check that tomorrow, if they are OK looks like it could be the fuel pressure reg, I only checked it coming from the pump to the reg, not after the reg


From a fuckin iphone....
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
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