Need help removing the fuel tank cap flange

[eyduc]

I have a 620 steel tank that I am cleaning the rust out of.  I want to remove the fuel filler flange to ease flushing it out.   It is quite corroded and the set screws are stuck.  I successfully removed only two.  The others had to be drilled out.    The flange still won't budge.   Is there anything else I'm missing to remove it?

After removing the flange, I want to remove the guts for inspection (pump, filter, lines, etc.)   I also want to test the fuel pump.   Can I power the fuel pump dry or will it get damaged?  I wouldn't run it for more than a few seconds.

[ducpainter]

If you're sure the set screws are completely removed, stick a hammer handle in the filler opening and give it a whack with the palm of your hand. Keep your other hand underneath it to avoid denting the tank.

If those screws aren't completely removed you'll damage the tank.

You can cycle the pump, but it really doesn't mean much without actually testing for pressure.

[eyduc]

Ok, thanks.  I'll have to double check that all the screw pieces are out and try again.   I was thinking that the body was threaded or there was a hidden screw.

[lazylightnin717]

How were you able to drill out those set screws?

[eyduc]

I didn't do a very precise job.  I just used a drill in from an angle.   I assume the flange is no longer useable.   I was planning to replace it anyway.  So I wasn't trying to save it.

[otter1]

Replaced the internal on my tank this spring. Had a hell of a time getting the flange out. My thread is on here in the tech section --stuck gas cap.

Lots of hammer handle action prying HARD at 12, 3, 6, 9 o'clock positions and finally it came loose!!

[eyduc]

Thanks for the responses!   I got it out last night by hammer and drift.   It was quite stuck with rust.   The whole inside is quite rusty.  I'll have to do another vinegar and salt soak.    I did drill too far and now I have holes in the neck of the tank.  I'll just weld the holes.  I still may be able to use the flange by redrilling the holes, tapping and use bigger set screws.   The internals are trash.  The pump is seized.