tank vacuum?

[overdriveeng]

How much vacuum should the tank be under? I keep hearing loud clunks from the back when activating and deactivating the fuel pump, and I'm starting to suspect it may be putting the tank in such a state of vacuum that its causing the steel to distort, making it "ping". Do these cars run pressurised / vacuum'd tanks?

If not, would this feasibly put the pump under enough strain to knacker it? It is getting noisy from time to time, although often shuts up once it hits pressure...

I'm starting to ssupect my pump may be the cause of the juddery running. Never one to simply replace a part, is it worth upgrading to a Walbro high LPH pump?

[overdriveeng]

This is interesting. I had it stalling last Thursday on an impromptu commute to work. I put it down to damp, but when I dipped the clutch it would die on me.

I think charcoal delete will be added to my winter list.

[overdriveeng]

Just to touch on the other point, would there be logic and recommendations to up rating my pump? It's intermittently whining so is due the chop in my mind.