1972 Chevy fuel tank safety

So, the '72 Chevy pickup has the tank behind the cab. And I am converting it to an in-tank pump. There is a slightly (in my mind) increased risk of fuel leakage, as the line was previously under vacuum and is now under pressure. For a low budget build, what would you do? There's a couple different possibilities I can think of.

1. Replace all rubber line with high pressure spec hose and pressure test the system thoroughly. Otherwise leave everything the same.

2. Cover the tank and lines with a fiberglass fire blanket.

3. Fabricate a rear firewall from sheet metal.

4. Replace the tank with an under-the-bed design. On this truck, requires fabricating some sort of fuel filler setup, which can easily turn into a major bodywork project.

So, what would you do if this were your truck and your money?

Since it is my truck and is my money on my truck, I am relocating to a skinny beside-the-driveshaft tank. I want the extra space and I can't stand the smell that will inevitable be around just because of the nature of the grommet at the filler neck. If you're Bush-League, you can always drop in a $50 Blazer tank and put the filler on the bed floor. It's cheap and a lot of folks do it that way, but it's ugly and you can't get gas when you are hauling stuff.

If you're not worried about the smell, #1 is the only option, the other two are silly. #2 won't do anything at all because the fire won't be on the tank or lines, it will be on the stuff the gas sprays on. #3 is ridiculous and you definitely don't have the space to do that well.

If it makes you feel any better, Mercedes Benz, you know, the company that invented the crumple zone, has been putting gas tanks behind the backseat since forever ago and probably still do today.

I'd just use the good injection grade hose for connections and steel line between the tank and engine. done right, you should have less than a foot of fuel hose in the system.

I'm pretty sure that Colin Chapman invented the crumple zone.

Dr. Hess wrote: I'm pretty sure that Colin Chapman invented the crumple zone.

Yeah, he called it the "Lotus".

HA! No, I'm just kidding.

He called it the "driver".

The guys on Trucks put a 67-72 Suburban fuel tank in the back of their 71 C10 and had the filler on the side, behind the side marker. Pretty straight forward and kept the bed usable.

I've put those tanks IN trucks with none of the problems you're imagining.

They're not as much trouble as people like to make them out to be.

I think you're just overthinking things but if it really worries you, the Suburban tank is probably the way to go.

Don't forget. Toyota put tanks behind the back seat for years with no trouble. VW and Ford put them over your legs. International put them in the front fenders. I'm surprised no-one has ever put one in the roof at this point.

Is a high flow mechanical pump not an option at all? My factory unit held 6.5 psi at idle and never starves. A high flow mechanical can get you way up there with no lift pump.

I own a 70 model F100. It was factory ordered with no fuel in the cab. They had no factory side mount at that time... When I disassembled my truck (frame off) I could show you the torch and rough weld marks they did in the factory to make my special ordered truck a rear tank truck.

They torched through the base of bed and inner skin of bed then covered it with a notch of scrap steel. All clearly made by an overachiever in the factory... With scrap parts.

I could replicate another one easily and not have 37 bolts integrated into the steel fuel shroud that makes you want to break your arm in 3 places and use it like a little meat colored swivel everytime you remove the bolts.

It has a sweet fuel tank shaped toolbox behind the seat mounted in factory tank location.

I would either build or buy me a tank and put it between the frame and d shaft. Place the filler and vent (invariably your pump and sending unit) about six inches rearward of the foremost of the bed.

Run you a filler neck over the frame and cut a 2 inch hole in the outer bed skin. Run the neck through the rough holes in your bed floor and inner bed skin, cover it. Then buy you a factory filler neck grommet and cap from another model. Put a light skid plate under it and go on.

I'd also take my old fuel tank and turn it into a sweet toolbox.

At this point, I'm probably going with option 1 until either I want to go drag racing (won't pass NHRA tech) or my wife complains about the fuel smell. I wasn't terribly worried about the risk myself, but have had a couple people get worried when I posted my build thread in some other forums.

FranktheTank wrote: Is a high flow mechanical pump not an option at all? My factory unit held 6.5 psi at idle and never starves. A high flow mechanical can get you way up there with no lift pump.

The factory injectors on the motor I'm installing need around 65 psi of pressure. Mechanical pumps in that range exist, but are seriously not worth the money for what I'm trying to do.

Another thought, if you're that concerned with pressurized lines in the cab, why not just use a pump on the frame rail instead?

Kenny_McCormic wrote: Another thought, if you're that concerned with pressurized lines in the cab, why not just use a pump on the frame rail instead?

I'm not particularly worried about it. Just had a couple people comment, "Hey, that looks unsafe," and I was wondering how many A frame rail mounted pump would be pretty easy to do, but I like having the pump in the tank for quieter running.

I, for one, would just run the in-the-cab tank if you're not interested in cutting up the body for a rear-mount setup.

A thought came to mind while reading the thread though: You could run one of those toolbox/tank setups if you want. I realize you might not be interested in this for a variety of reasons, not least which, aesthetics.

They were big with the waste-vegetable-oil crowd when I was researching that. Not sure if it's any more NHRA or DOT legal than other options...so there's that.

I'd go to the junkyard and source a tank from a late model 2500 and fit it up under the bed, run new hard line to within a couple inches. Use the return as a vent out behind the rear axle with a filter to keep the bugs out.

Sounds like the perfect scenario for a swirl pot to me. Tank in the cab stays under vacuum, pump meets whatever pressure requirements you need.

As to building said swirl pot, I suggest starting with a $30 air ride tank from e-vil-bay. Plenty of ports for your inlets and outlets, steel so anyone can weld on a flange if needed, and they usually come with brackets you can use to mount to the side of your frame.