Bike not responding to open throttle

tophurler

Hi Guys,

BMW F650GS Twin.

Wondering if anyone has suggestions for the following issue I experienced at the weekend. Went to open the throttle fully to overtake a car and the bike didn't respond, speedo didn't budge, revs didn't climb. When I closed the throttle to about 1/3 the acceleration kicked in again.

I can increase speed gradually with the throttle 1/3 open, but when I tried to open it up the bike doesn't play ball. Seems to be happening in all gears.

Has anyone any ideas?

Thanks in advance.

cantdecide

Throttle position sensor? Is it a known issue for that bike I wonder? That's where I'd start my googling anyway.

frozenfrozen

does it do the same thing in neutral just revving the engine

tophurler

cantdecide wrote: »

Throttle position sensor? Is it a known issue for that bike I wonder? That's where I'd start my googling anyway.

I'll give that one a google thanks

tophurler

frozenfrozen wrote: »

does it do the same thing in neutral just revving the engine

I actually didn't check the bike in that state, I'll give it a go and see.

Could be a vacuum leak , check the rubbers going to the engine

Has this happened out of no where? .

pudzey101

Lauren Prehistoric Tariff wrote: »

Could be a vacuum leak , check the rubbers going to the engine

Has this happened out of no where? .

+1

Check the fuel tank breather pipe. If that's blocked a vacuum is created leading to fuel starvation. Make sure it hasn't been pinched and also the end where it exits underneath the bike is clear and not blocked with road gunge.

tophurler

Lauren Prehistoric Tariff wrote: »

Could be a vacuum leak , check the rubbers going to the engine

Has this happened out of no where? .

I filled the bike in a place I have never used before, the bike ran perfectly for the next 2 hours. Returned to it later that day and happened during the ride home.
I have asked around about the particular filling station and does not seem to be known for poor quality petrol.

tophurler

pudzey101 wrote: »

+1

Check the fuel tank breather pipe. If that's blocked a vacuum is created leading to fuel starvation. Make sure it hasn't been pinched and also the end where it exits underneath the bike is clear and not blocked with road gunge.

Thanks Pudzey I'll have a look at that

frozenfrozen

did you run down the tank more than usual if you ended up filling in some random place you weren't sure of? could be sediment from your tank is now caught in the low pressure fuel filter

tophurler

frozenfrozen wrote: »

did you run down the tank more than usual if you ended up filling in some random place you weren't sure of? could be sediment from your tank is now caught in the low pressure fuel filter

It did get a little lower than I normally like it to get before a fill alright. It was the first spot I was hitting for fuel on my route. Would it be a case of having to remove and clean the filter if that was the cause?

frozenfrozen

Check other stuff first mentioned by everyone else here but you could do that if other stuff doesn't help its a very easy job. Hoses and connections off tank remove tank from bike 6 screws to pull the pump assembly out then you remove the case of the pump and clear the low pressure filter.

Wouldn't be the first thing I'd check though go through the basics first

tophurler

Just checked, it is revving fine while in neutral.

frozenfrozen wrote: »

does it do the same thing in neutral just revving the engine

frozenfrozen

tophurler wrote: »

Just checked, it is revving fine while in neutral.

Ok and are revs climbing and falling at a normal rate or does it hesitate anywhere along the rev range. if it does then that would be a sign of a vacuum leak.



any other info that could help someone point to what it could be, like did the bike sit for a long time, when was the last time it ran perfectly, any drops even in the driveway, does it smell & sound the exact same as before.

does your bike start easily and is the idle lumpy or smooth too and does it idle higher or lower at the moment than it used to

all those kinds of questions you'd need to go through and then figure out what it could be and just start attempting fixes

tophurler

Just a little update on this issue.

Stuff checked to date
1) Spark plugs, in good condition. Gap checked and at recommended for bike.
2) Fuel pump removed and filter is spotless.
3) Air filter checked and clean.
4) Injector cleaner placed in tank.

After all the above (and battery being disconnected for a time) I took the bike for a spin. The issue was not there for maybe the first 2/3 minutes of the ride, before returning.

Next up:
I have managed to acquire a throttle position sensor which I will swap in and see if it makes a difference.
I will also check the breather pipe.

serious3

First thing what colour is the fuel pump controller on top of the tank? If it's black that's the newer one, if it's silver bin it and get a later model one off a 1000r, 1200gs etc, they're all the same.
Second check the side stand switch, there's a way of bypassing it, can't remember though.... mine did exactly like your describing and I chased my tail for months, turned out to be faulty sidecstand switch, there are recalls for this on this model so check with your dealer

GerryDerpy

Is she a fly by wire throttle or mechanical cable?

Wossack

try running the bike with the tank cap left open (carefully, ideally nearly empty), see if that has any effect

two wheels good

On boxer models there a "TPS reset" procedure. Maybe it might help.
The purpose is for the ECU to learn the closed throttle and full throttle positions from the TPS.

I've copied this from elsewhere:
1) Disconnect battery for about 30 seconds then reconnect (causes ECU to lose it's memory of Throttle Position Sensor).
2) Turn ignition to ON - but DO NOT start the engine.
3) Slowly wind the throttle fully open to fully shut, repeat this three times.
4) Turn off ignition. (ECU now stores TPS position data in memory).
5) Wait 5 seconds.
6) Turn on ignition again and start bike.

Also: I expect you'll need to adjust the TPS if you remove\replace the unit. (Maybe you know that already.)

tophurler

Just to update, eventhough the plugs looked fine on inspection I purchased a new pair and the problem is no more! Thanks to everyone for the helpful suggestions ðŸ‘ðŸ‘