https://club8090.co.uk/forum/viewtopic.php?f=2&t=44597" onclick="window.open(this.href);return false;
I have just sorted it out and what i found could be of interest to those who, like me let the tank run a little too low.
1. a small down slope will not help at all, get the Van level (If you can)
2. the inside of the tank appears to have a syphon in it. So to get fuel back into the delivery pipe after this is dry/empty you will have to either attach a long hose to the fuel filter and suck (Very Gently) or have the Van uphill so this section of the tank in under the fuel level.
My Van was on a slight down slope I ended up putting 3 gallon in it, and jacking up the nearside wheel to get the tank level (ish).
Now as the Van fuel delivery system is a sealed system any air ingress into this section will stop fuel delivery, I recommed you check all your fuel pipes before trying to start the van.
I found that the small section of pipe between the tank outlet and filter inlet was broken/rotten (I could have done this when removing the filter), which caused me no end of trouble as i could not get the syphon in the tank full of fuel and fill the filter ETC.
heres the state of the pipe after i removed it.

After i replaced this, I blew down the pipe i had connected to the filter outlet ( this was connected to the tank by the new pipe), the tank gurgled away nicely, i then sucked gently which filled the new pipe and filter, then reconnected the rest of the fuel pipe.
I then opened the vans engine cover, whipped off the air box cover & slugged a capfull of petrol into the carbs, then turned the engine over, the van spluttered along then died after about 3 /5 secs, i repeated this and at the next start the engine ran ok.
Hope this helps
Your best bet though is to keep the tank well topped up as its very flat, and down slopes could catch you out real easy.
Fraggers (Ian)