Mysterious Rust in Fuel Tank

[abrahamseven]

Hello, I am new to this forum and trying to figure out where to post my problem or even if I can. I signed up to learn how to weld better. However here is my story, I will Make it short:
I bought a NEW steel fuel tank, I had the neck removed on the new one and replaced with the old , it was custom made, Installed the new fuel tank put 5 gallons of premium gas with ethanol , in less than 5 days the filter plugged up with a tan powdery stuff and the bottom of the tank rusted. I have pictures, my question is, could the heat from the taking the neck off and replacing the other one cause the metal to break down and cause a reaction to the ethanol ?
I would really appreciate some guidance here and don't be bashful . If I am out of line tell me.


steve

 

[the snooper]

when you had the neck removed was it cut off with a grinder if so thre is your answer fragments of steel from cutting it off

 

[bill_gj]

Excellent question, re the method of cutting off the filler.

By the way, how much ethanol is there in your fuel?
Alcohols absorb water.

 

[pedrobedro]

I made a fuel tank from 18g steel sheet and it was flushed and tested after I made it. It still managed to block two filters before it was clear of particles and I always carried a spare with me. I put it down to scale from the welding forming on the inside of the tank seams and getting carried through the pipe to set in the filter.

 

[hotrodder]

Could be lots of things, my money's on any or all of the following...

As said cutting disc dust/scale from the welding although swapping a filler neck isn't going to result in much. If the tank was 'coated' internally to reduce corrosion then the coating will have been damaged locally to the weld- another potential source of debris. Having said that if the tank has a load of surface corrosion inside it's probably not coated (although some of the older tank sealants are supposidly vunerable to ethanol fuels/blends) and is probably due to the hydroscopic nature of ethanol

Mate of mine built himself a '32 roadster the other year, i had to modify the new repro tank to get it to fit. This brand new tank was full of crap, bit's of polystyrene, plastic and general dirt. I flushed the thing several times after welding and testing it, still clogged several fuel filters in short order before it settled down

 

[scarecrow]

I had seen this before as well but only in older fuel tanks when the coating started to break down I think there is some products to reline the inside of the tank but not sure how successful this is