[d.wamsley]

Hi my sierra is running with a big flat spot if I have more than about 10 litres in the tank. Have replaced fuel pump and filter. I was thinking carby until it started to run as normal with low fuel level. I have put 3 full tanks if fuel through it and runs shitty until getting to a low fuel level. I'm just putting 10 litres in at a time and it's running great. Gauge is also playing up. Can the sender be causing this problem. Breather line seems to be ok and unblocked. What is the purpose of the small plastic tank near the filler tube? Any input appreciated.

[christover1]

Carbon canister is worth checking.
Does sound like a breather system fault.

[d.wamsley]

Disconnected everything and removed tank and flushed it out. Blew out the lines and has seemed to improved. Time will tell and I will slowly increase fuel amount at each refill

[christover1]

Make sure no hard lines have been crushed, a problem from rock encounters.

[kenn]

As Chris said, carbon canister it's in the engine bay.

[droverdave]

Also check the fuel cap.

Not sure if the suzuki one is vented or not.

Try driving it without the fuel cap on properly (to let air in via the cap) and see if it helps.

[d.wamsley]

Thanks for the tips. It's running heaps better now and seems to be getting more fuel through. I think I will bypass the canister anyway just to be sure.

[christover1]

Consider the position of breather hose carefully, if bypassing cannister (temporary to test theory of course )
If breather is in the wrong spot, fuel can syphon out on angles off road.
Also fuel can escape if you topple or flop the car.
Most early cars just had an open ended breather tube,
but mud and water can easily get in, so a filter on the end is wise.