Technical Fiat 900t fuel tank

[phate316]

Ive discovered that the fuel tank on my wifes fiat 900t was full of rust and sludge, after being dry stored for 20 years, ive taken it off and flushed it through until no deposits are left in the filter funnel, i kept wrinsing it out with the petrol that was in the tank and refiltering it before it went back in the tank each time, also shaking it and tapping the filler end on the ground on a dust sheet each time to dislodge as much as possible, so its clean now, ive also sealed up the holes and pressure tested it with a plumbers pressure test kit and theres no leaks, and the metal outside looks in good shape..
Do i need to have it resealed or will it be ok to use as is, ive got a fine gauge fuel filter in line, will the fuel in the tank keep it from corroding more
Sorry for being so long winded

 

[spannerdude]

I am investigating the same issue. My fuel filter is full of rust.
The suspected problem is that modern Bio fuel mixes containing ethanol which is hygroscopic. The water settles out of the fuel in the tank. Bio fuel also corrodes pretty much all of the metals used in the fuel systems of classic vehicles, zinc, aluminium, brass, copper, lead....
At the minute most bio fuels are 5% ethanol but there is a push to move to 15%. Other countries, like the states for example have already got 15% available. It will be interesting to watch what happens over there...