The Stovebolt Site Forums The Shop Area Engine Shop 1955 4400 Fueling System

I thought about putting this in the Big Bolt section, but this might apply to other trucks with tanks in locations other than behind the seat.

The factory fuel pump seemed to struggle to 'properly' and reliably deliver fuel to the carburetor from the side mounted fuel tank, located on the drivers side frame rail behind the cab. I think this was because of a few compounding problems, the tank is considerably lower, and farther from the pump. When the fuel level is low the fuel pick up is lower than the engine pick up. The factory fuel pump would have to suck the fuel up with no gravity assist. When the tank was in the cab the fuel would almost always be above the pump so it could gravity feed to it.

Additionally another unresolved issue was a considerable amount of trash clogging up the fuel filter that was mounted up near the carburetor. Long story short it was too small for the quantity of debris.

My solution started with mounting an electric fuel pump on the frame rail closer to the tank. Spectra SP8016, pressure is advertised at 2.5-5 psi. Since this I haven't had any problems with fuel delivery at any fuel level.

Also I installed a spin on marine style fuel filter similar to this. It hasn't plugged up yet, so I suppose its an improvement.

These are mounted on the frame rail under the drivers door, out of sight, so slightly more in keeping with the original looks of the truck; pretty cheap too.

Since these mods, I've noticed excess fuel around the carburetor, and possible flooding at low loads, like coasting down to a stop. Maybe worse fuel consumption - but who could tell... Right or wrong I decided the pump was probably putting too much pressure and pushing past the float - or somewhere else. I had hoped that since the V8 engines could run up to 5 psi the pump wouldn't be too much. Instead I put in a fuel pressure regulator 1-5 psi and for the fun of it a small pressure gauge. I basically picked the two cheapest ones on Amazon. While I don't like the idea of these being mounted right in front of the carburetor, looks, the regulator has an adjustment knob on it and didn't seem well suited to being mounted on the frame rail down below and what good would the gauge do me down there?

With the regulator set to regulate to around 3.5 psi on the gauge, engine isn't stalling out while coasting down and is presently running quite well, as best it ever has. Additional notes, its timed as far advanced as possible without pinging.

In summary, this fuel delivery system seems to be a good combination for where my tank is, very low cost, simplicity and if I desire, I could probably make it appear close to period correct. Right now it is a rubber line from the tank to the last 6" of remaining hard line going in to the carburetor. For a more period correct look I would switch to hard lines and then some combination of relocating the regulator and a different gauge situation, for now it works well for tuning the system.

If the fuel filter is clogging up with debris and reducing gas flow then, in my opinion, you are attacking the problem from the wrong direction. Work backwards from the fuel filter to the gas cap. As an example:

If you or previous owner have used today's 10% or higher Ethanol gas and the truck was allowed to sit for a long period, regardless of additives, with fuel unused in the tank, most likely you gas tank is full of rust. Steel fuel lines and steel parts in the fuel pump and carburetor will rust. I took pictures of mine before I replaced it all. You are welcome to have a copy. I have posted it twice before in this forum. You can upgrade all your fuel system components to handle Ethanol or if you want to remain original, replace it all and only use non-Ethanol gas.

I seriously doubt the GM engineers undersized the pump. A lot of trucks have use the same parts for decades.

I’m sure there is rust in there! But that was the harder job, I wouldn’t say it’s off my to do list though.

The attached picture is what my original tank looked like inside.
I removed the level sensor so I could take a picture through the opening.
This is what happens when Ethanol is used in fuel systems that were not designed for it.
The truck ran poorly (underpowered) and I had to use a little manual choke all the time.
Both fuel filters, fuel line, fuel pump and carburetor were red with rust inside.

Filtering debris from a rusty tank is like taking Tylenol for the headache caused by a brain tumor. Things aren't going to get better even if the symptoms go away temporarily.
Jerry