Fuel starvation/hesitant running

[gutsi]

Here's the scenario: trackday at Cadwell on Wednesday, 1100 GS running well and out cornering all, uses a full tank of fuel and orange fuel light comes on couple of laps before ending final session. On leaving circuit go straight to nearest petrol station 15 miles away, notice that fuel pump is noisy (as in when you first turn the ignition on) half way to petrol station. Bike is a little hestitant but I take it easy to conserve fuel. On arriving at petrol station fuel pump is still whirring away. Fill up with fuel noticing that tank has vacuum and I need to clean breather pipe. Bike hestitates all the way home. Today on 30 mile ride notice bike still hesitates so on way back I unlock fuel cap and leave part open to check that vacuum in tank is causing bad running. The bike still hesitates.
Question: If I run really low on fuel can I introduce air into the injection system? If so how do I bleed it?
What else could be causing these symtoms?
Obviously I will sort out the tank's breather arrangements but I want to fix the main problem.

 

[cookie]

Question: If I run really low on fuel can I introduce air into the injection system?

i think not

 

[Fanum]

Sounds like you may have sucked some shyte into the injectors or fuel pipe by running it so low.....maybe some paint from the lining of the tank or just some general crap that goes in on the fuelling nozzle when you fill up.

Hmmm...no, let's go backwards.....the same cause but hopefully it's just stuck in the fuel filter.

I think that'd be my first place to look in your shoes......and while you're there, replace it with a new one on the outside of the tank to make it a 2 min job to replace next time.

Oh yeah, and be very careful with the float arm when putting it all back together.

 

[Frank Warner]

Question: If I run really low on fuel can I introduce air into the injection system? If so how do I bleed it?

Yes. The pump will suck air if that is all there is to pump. The air will clear out as the bike runs or you turn the ignition on and off a few time (that get the pump run for 5 seconds a time) [assuming the pump now has petrol to pump].

What else could be causing these symtoms?

Clogged fuel filter.

To fix the problems do them in this order

1) clean out the fuel tank breather system - get rid of all the dirt.

When clean

2) relpace the fuel filter. You should carry a spare as you could pick up dirty fuel anywhere. At least buy two fuel filters and put one on the shelf for next time.

 

[Spout]

Hi Gutsi,
don't rule out coincidence! It might not be fuel system related.
I had similar 'hesitation' on my 1150 after filling up with cheap petrol. After months of replacing fuel lines, filter, TPS etc to find a cure, it turned out to be my Llamda probe.
Good luck........................

 

[gutsi]

Having taken all your advice on board and a chat with Trev at Motoroworks I'm replacing my fuel filter and cleaning the inside of the tank. However I've found a oval float loose in the tank unattached, can anyone identify it? It about 80 x 45 x 15 mm overall and the partno is 16.11-2313092.
It isn't the float for the fuel guage as that is more angular and is still attached.

This one looks like it takes an arm which bolts to the centre.

Btw I've found a lot of water in the bottom of the tank, apparently this is a comon cause of bad running and is related to the increased hydroscopicity of modern fuels.