Petrol pump question

[seeby]

My Chim 400 runs very smooth ,pulls well , tickover constant 800,until....... the fuel level drops just under the quarter tank mark. Then it drives lumpy and tickover ranges between 0 and 2000 occasionally cutting out . It happened today but once I put 35 quids worth of v power in it runs loverly again ??. A mate said it might be the pump low on pressure .Could it be this? How can I check the pressure ?

[jojackson4]

What happens when you remove the cap ?

[seeby]

jojackson4 said:

What happens when you remove the cap ?

Mm tried that one. Sometimes (hot weather) it releases the built up air,other times ie today,no air build up . That doesn't seem to affect the running .

[jojackson4]

Blowing or sucking ?
Stop it

[seeby]

Oo er blowing. (letting it out )

[seeby]

Oo er blowing. (letting it out )

[phazed]

Must be sucking.

Loosen cap at 1/4 tank then try.

[jojackson4]

As above

I bet it sorts it

[seeby]

I,ll give it a try ,cheers

[zed4]

phazed said:

Must be sucking.

Loosen cap at 1/4 tank then try.

Is that indicating a problem within the fuel tank breather circuit? Something wrong with the carbon canister perhaps?

[phazed]

zed4 said:

phazed said:

Must be sucking.

Loosen cap at 1/4 tank then try.

Is that indicating a problem within the fuel tank breather circuit? Something wrong with the carbon canister perhaps?

Quite so, it's not letting air back into the tank.

[zed4]

phazed said:

zed4 said:

phazed said:

Must be sucking.

Loosen cap at 1/4 tank then try.

Is that indicating a problem within the fuel tank breather circuit? Something wrong with the carbon canister perhaps?

Quite so, it's not letting air back into the tank.

I inadvertently ran my fuel tank down very low yesterday (forgot to fill up in the morning!) and noticed there was a hiss when I removed the filler cap. I might check the breather pipe.

[phazed]

Breather runs from tank, by filler neck, along chassis to front offside wing where the canister is.

Sometimes the tube gets clamped/squashed as it wends its way along the chassis!