1979 C600 with 370 gas under a 4bbl, 5sp trans, and 2sp diff. It has dual tanks, one on each side. I think they are 50 gallons each, but I am not sure, nor does it matter much at this stage. The way I bought this truck, the previous owner had disconnected the passenger side tank and ran an electric fuel pump directly off of the driver's side tank.



There are three threaded ports across the top and a neck with a vented fuel cap in the center. One of the ports is capped. One has the feed line to the electric fuel pump. One has a hose that leads nowhere - I am betting this was a shared vent system from before the system was butchered. There is also a part held down by screws with a ground wire coming off of one of the screws, connecting it to the frame. This ground wire is not present on the passenger side tank. The guy I bought it from said that if I wanted to hook the passenger tank back up I should drop it and clean it out really good.

Now that you know what I have to work with, you can chime in on my project...

I want to drop the passenger tank and clean it up. Recommendations for that would be cool to begin with. While the tank is dropped, I want to clean it down to bare metal and paint it. I am re-doing this truck and I want it to look nice so painting anything that is off, before it goes back on, just makes sense. Is there any certain paint that is more resistant to fuel spills? I will also drop the driver's tank, clean it up, and paint it to match.

Next phase is to drop the passenger's side brackets, move them to the driver's side, and re-mount the tank so that both tanks are on the driver's side. I know that they are split like they are for a reason. The natural way the weight stays even as you fill or drain them would normally be great. However, Ford designed the tanks to be switched between. The weight distribution is no longer automatic. Also, this truck is being built into a flatbed tow vehicle. Any little bit I may benefit from splitting the tanks is outweighed by the fact that both tanks on the traffic side during a roadside repair leaves me to have more tools on the safer passenger side.

Here comes the tricky part - How to feed?
The simple way would be to extend lines and hook them up like originally installed. I kinda like automatic things though, so I had an idea. What if I were to swap out one of the vented caps for one that is not vented? Put that on the front tank and leave the rear tank vented. Feed the motor off the front. Run the vent line of the front tank to the bottom of the rear tank. Since that line is the only way for pressure to equalize, it should suck fuel from the rear tank into the front tank as fuel from the front tank is burned. If the rear tank runs empty, air gets sucked into the front tank, which vents it just like normal. If you want to burn fuel off the front tank without sucking fuel out of the rear tank, just switch gas caps. As long as the front tank is vented on its own, it will not build enough suction to pull any fuel out of the rear tank, unless a blockage or some other special circumstance takes place. My question is, will this work? Is there anything that could go wrong with my design? As long as everything stays air tight, the only 'maybe' problem I can see is that the fuel pump would have some extra work to do having to feed a tank into a motor and a tank into a tank at the same time. Thoughts? I can draw it if this sounds confusing.

 

I'm not a large truck guy, so I'll avoid the rest of your questions...

However, take the cap off and shine a light in there. That "part held down by screws" - is that a float? And if so, that wire is really under one of the screws, or is it in the center of the "part" ?

 

My suggestion would be to grab a pair of clean newer tanks off a 1980s or 1990s F600,700,800 truck. They come in 35 and 50 gallons and they have a equalizing plug in both sides of the bottoms of the tank so all you would need to tie a pair together is a short length of hose.

Check the local yards, I paid $100 for a tank and all the brackets, straps, and hoses and it came half-full of clean fuel!

 

The fuel tank sending unit (retained to the tank w/5 bolts) is shown in the pic to the left of the fuel cap.

 

Ahhhh thank you for that. I hadn't had a chance to go out and peek around inside the tanks yet. I want to use the originals, if I can. I already have them and they fit the frame nicely.

 

I think it is safe to say it takes me a while to get around to things. I pulled the nuts off of the passenger side tank straps today. I couldn't believe that, when you compare the hardware from one side to the other, no two pieces match. It makes me think someone kicked the originals away and just used whatever was under the workbench in its place, last time this tank was dropped. I am replacing all the exterior hardware on this project with new stainless steel, so this won't be an issue in another 38 years.

 

 

^ Thank you for this!

 

So here is the inside of my passenger side fuel tank, after draining. I am actually glad that it seems to be more sludge-like than rusty.

 

Sounds like the LN8000 I'm working on, 6V53, RT610 roadranger from a Dodge D5N, single speed Rockwell rear axle from a White (I was told) twin Kenworth tanks, International gauges. Ford D (English) series passenger seat and a mix of every size bolt you can think of.
The ol farmer did what he could to keep in on the road I guess.