Repairing & Sealing KITT's Fuel Tank, Part 1

posted Jan 5, 2013, 7:40 PM by Jonathan Imberi
I started on KITT's fuel tank today. I bought a Fuel Tank Repair Kit from POR-15 a few months ago but have been putting this off because I knew it was not going to be fun.

The first step was to remove the fuel sending unit/fuel pump assembly.

I know I said this the last time I had the sending unit out, but I am still really surprised at how good of shape it is in.

Here is a picture of what the inside of the tank looks like. There was still a little bit of fuel left in the tank. I had to drain this out before I could begin the cleaning process.

The next step is to pour a quart of Marine Clean and a quart of hot water into the tank. Normally this is done through the fuel filler neck. The tank I have (along with most third gens) has a fuel restrictor at the opening of the neck. This will not allow fluid to flow in and out of the neck. I ended up sealing off the filler neck with a plastic bag and then threading the cap back on. I poured the Marine Clean and water in through the fuel sending unit opening and then attempted to seal that opening with duct tape as recommended. 

Then you are supposed to shake the tank vigorously. "Yeah right" is all I have to say about that. The tank is not heavy but it is bulky and is not the easiest thing to handle by yourself. I sloshed the liquid around and turned the tank on each end so that the Marine Clean would have a chance to get to the entire inside. This process worked well until it came time to flip it upside down. Let's just say the duct tape did not seal the opening. I had Marine Clean and fuel sludge running all over the place. I attempted to clean the top of the tank as best I could while not losing too much through the opening. Once this sat for twenty minutes, you are supposed to dump it out and rinse the tank out with water. The problem with trying to use the fuel sending unit opening is the way the tank is shaped, water gets trapped in the middle baffles inside. You end up tipping and turning and flipping and rolling the tank until all the water comes out. 

The next step is to repeat the same process with the second quart of Marine Clean and a quart of hot water. I tried to get creative this time around and use the o ring and the lock ring for the fuel sending unit and a plastic bag and tried to make a gasket and seal. This worked about 75% better than the duct tape. No leaks for the first five minutes... and then it ran all over me. 

I was not happy with the thought that the top of the tank was not getting cleaned as thoroughly as the rest. So I thought "there's got to be a better way!" and then it hit me: Sara's flower pot. The flower pot was about the same diameter as the opening, so I pushed the narrow end in until it fit snugly, and then duct taped it down. This worked 99% better than the duct tape alone. I only had a few small drips.

After another twenty minutes had gone by, it was time to dump and rinse the tank out. I tipped and turned and flipped and rolled the tank until I got all the water out into a tub.

The cleaning part of the fuel tank sealing process is finished. The inside of the tank is clean.

Here is another shot of the inside of the fuel tank. As you can see there are just a few tiny specks of surface rust. What you can see in this picture is the worst of it. I think I am pretty lucky; the inside of this tank is in really good shape.

I decided to clean the outside of the tank with Marine Clean before I prep and seal the inside. This way if I find any areas that need to be repaired on the outside I can do that before the inside is sealed. There is significantly more rust on the outside of the tank than there is in the inside. I will be painting the outside of the tank with black POR-15, but because of having to use the fuel sending unit opening, I am afraid there will be no way to neatly pour the sealer out of that opening, and I do not want to ruin the nice looking paint. So I am going to seal the inside first, and then paint the outside.