Gummed up gas tank
 

So, used a marine tank cleaner on this gas tank, and boy did it do work. But now the problem is that all the varnish and other such stuff that was built up, is just kind of gum on the bottom of the tank. Any ideas on how to go about getting the stuff out? I want to try a shop vac, but have read that it's rather risky because they could explode.

Before cleaner

After cleaner

It's sitting with gas above the line on the side now with more cleaner in it to try and get that other stuff off. I have enough for maybe 3-4 more cleanings if need be, but I wanna try and get that gunk out of there before doing any more cleanings.

Stick a power washer wand in there to break it up.

Might be a silly question, but did you remove the drain bolt on the bottom of the tank ?

try some degreaser, then some white vinegar

dont have it boiled out

Any suggestion, or will any degreaser do? Gunna be a loooot of vinegar.

Yep, this is after draining the original 8 year old gas, and filling it up with new plus a marine tank cleaner. Let it sit for 2 days and drained it again. Came out lookin like ice tea, and that was what was left in it when it stopped trickling out. I have a second batch of fresh gas and more of the cleaner in it now to try and get the last of it off the walls and the slope of the bottom.

I'll see if I can get my dad to borrow his, otherwise don't really have one available.

i filled my tank with vinegar and let it sit a few days before I coated it with Red Kote
a good quality degreaser used full strength, you can also reach in and surprisingly scrub alot of of that with your hand

Take the tank to the local self-serve car wash, if one is available.

Unless you are built like "Barney" you should be able to get the gunk out with some good cleaner and lots of rags or Paper towel.

*Aaron Cake had a thread or 2 up on tank cleaning.I believe he used either a POR based cleaner or a Marine type cleaner..maybe search that.

POR15 marine clean is amazing stuff. Might be worth getting their petrol tank kit. Put a chain or something in also to cause some agitating. Then shake away! :)

be careful with inserting chains and nuts and bolts in the tank, the seam is not all that sturdy and you might cause a leak, so dont go shaking too nutso

I used an industrial degreaser, then vinegar, then dawn dish soap

I did all this because we were restoring the undercarriage and thought it would be a good idea to strip the coating off the outside of the tank, had it boiled out so the welder would be comfortable welding a sump to the tank, then had it powder coated.
The boiling created a film to build up inside the tank, the tank sat for months and months wrapped up before I even looked inside of it
So i went through all that cleaning process and while I filled it with water thats when I found a small leak along the seam which I repaired then I Red Kote'd it