Thinking Of Plumbing My Two Tanks Together

[franklin2]

Thanks for clarifying how that valve works, The valve looks old and I really doubt it even works, they used cheap rubber hose that was split on the end, so I like the idea of just taking it out and replacing with a good hose, I think I'll try to run it up along the filler neck and punch it through so it's visible next to the filler cap, I want it up high and protected from mud, stock it was neither. Yes it will flow fuel when I'm upside down but I doubt I'll notice.

Putting the oversize breather pipe up high into the filler neck is the best option. I didn't do this, just ran the hose as high as possible up into the side of the bed cavity with a screen over it, and I had no dirt or water problems, but I would get a little spit of fuel foam out of the pipe each time I filled the tank. And I also found out you need to make sure there are no "bellys" or low spots in the hose. Over time fuel will lay in this low spot and it will stop the breathing function. I wondered why my tank was hard to fill again, until I discovered the hose had moved and had a low spot, and it was full of liquid fuel blocking the venting action.

 

[Mulochico]

Thanks for that post MULOCHICO, it gives me good confidence that this is a viable way to eliminate the FSV and 1 sensing unit (I'm tossing my rear), and a hand full of connections. The OEM FSV was built super good but after 39 years I know it's getting close to death and I'm pretty sure a new one won't last 39 years! Funny that you had a few problems with the fittings used to tap into the tank, I wasted lots of time running around town looking at every hardware and hydraulic store I could trying to find the right fitting but I was not happy with any of them so I spent the afternoon making my own from scratch. I decided to forego any shutoff valves (more to fail) and also am going with a very small line between the tanks, actually the line will be 1/2 inch but the ports in the fittings is only 1/4 inch, in my opinion smaller is just easier to seal and there's plenty of time for the fuel to transfer between tanks. I'm trying to fashion a bulbulus screen around the intake to prevent any debris from clogging it, that was my only concern with the smaller size.

Sounds like a decent plan. I would suggest supply and return to the front tank then all the smaller hose needs to do is transfer and it can equalize do it at a stop if needed. Hope yours work as well for you as mine has for me. I had the same reasoning for doing the transfer hose, couldn't find a decent replacement and wanted to have as few failure points as possible. The valves work for me as I am always tinkering and wanted a way to block off one of the tanks if necessary and as a benefit I can drain the rear completely and front over 1/2 way very easily if I decide to remove or just modify at a whim. Also most of the older semi's that had the lower crossover hose had shutoff valves in case of an issue

 

[Poorman]

Finally got time to sit down and finish this thread. I hate it when threads end before the project is finished and we're left hanging, so here's my ending. I finished the project several weeks ago and I'm really happy with it. Replaced all the fuel lines from the steel line that crosses from drivers side to passengers side under the engine back to the tanks with rubber line, bypassing the fuel selector valve. I couldn't find a bulkhead fitting that I liked so I made my own, as you can see in the following pics I just cut my washers out using a hole saw, then a counter sink to form an "o"ring gland, then welded the washer onto the end of the bolt after I had drilled a hole thru it and ground the threads of the bottom portion so it could except a 1/2 inch hose. It's a 9/16 bolt. Used some stainless screen from a food strainer to form the screen and attached it with j b weld, also used the same screen to form a filter on the new pickup where I deleted the showerhead. See pic. So the trickiest part of this project is just making sure there are no leaks where I tapped into the tanks, I think I'm good because It's got an "o" ring on both side of the tank wall plus a 1/2" of flat on both sides of the "o" ring that I sealed with Permatex aviation sealer and used it on all threads and hose connections. (I like that stuff). One tip is to use a step bit for drilling into the tank, I've never used one before and I was impressed, perfect smooth round and accurate hole, that can't be done with a regular bit or a hole saw. I only replaced the front sending unit, interesting when I removed it the shower head was still attached but when I set it on the bench it promptly fell off, the rear one was long gone. So the only weird thing is that the needle now stays on full until I have 18 gallons left then it heads down, I filled it 2 gallons at a time and made notes of where the needle is so I feel comfortable with it. The rear tank was rusty inside the front was not, not sure why, nothing loose just rust colored. No more anxiety when switching tanks!!

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[franklin2]

Tell us how it works at the fill station and how much fuel total you can get in it. I am wondering how much fuel you can get into the rear tank after filling the front tank. As your filling the front tank some fuel has to be making it's way to the rear tank. If you get 19+ gallons in the front tank, then we know a gallon or two is going to the rear tank while filling the front tank. Normally if you run the truck really empty, on a 19 gallon tank you can usually get around 16 gallons in it. There is usually around a 2-3gallon reserve built into the tank when the fuel gauge reads empty.

 

[Poorman]

Franklin, That's one reason for only a 1/4 inch hole in my fittings, it's large enough to transfer fuel for engine use but small enough to not transfer fuel to fast while filling and cause a back and forth fill need. Because the front tank hangs down lower and will need to fill about 3 inches to get up to the transfer hose, I'll fill it first then rear, then a splash in the front again if I'm really trying to top off. When starting the project I syphoned out all the fuel (28Gal) then put it back in 2 Gal at a time , you're pretty close Franklin, after pouring in 4 gal and waiting a few minutes the needle came up and just barely touched the (E) line.
I'd be curious to here from Mulochico and get his opinion on rather I made any improvement over what he used, he mentioned that he developed a small leak on his setup.

 

[Mulochico]

Your setup is definitely cleaner than mine. I didn't have access to welders or any machining type tools so it is a bit redneck (just like me). My lines are 1/2". After getting under to look at it I remembered that the only place it leaked was a small seepage at the valve on the front tank, I tightened it a bit and have had no problems since.

I like the idea of the screens and your connections look solid. Very good job. It looks like you shouldn't have any problems for a very long time.

Are you doing the pickup and return on the front tank? If so I would make sure you have the both lines in the rear tank plugged good and it vented well. I found out diesel sure has a way of getting thru connections, even when I thought they were tightened well.

Over the years I also found that not alot transfers as I am fueling I usually do the front then the back tanks just because the front is lower. As I still can switch between sending units I found that the front tank doesn't show any movement until the rear tank is at 1/8 or less. Most of the time I just leave it on the front tank and when the gauge starts to move I know I'm at about 1/2 on the available fuel.

 

[Poorman]

Mulochinco, Thanks for the kudos, I've found that I can accomplish a lot with a mig, drill press, drill, grinder ect. Our setup looks very similar, both use 1/2 inch hose, my fittings are 1/4 inch ID looks like yours is probably larger ID. Can't see how your sealing is actually done but it looks to be working good as it all looks pretty weathered and time tested. Yes, fuel and return only goes to front tank, I replaced rollover valves and ran the new vent lines along the fill spout and it terminates as high as I could get it inside the fill door, I just drilled a hole thru the plastic box that house the fuel filler cap. I opted not to put a valve in mine for simplicity. I cut the wires to the rear sending unit when removing the tank and didn't bother repairing as I only plan on using the front sending unit (didn't want to spend money on another sender) I did end up leaving the selector valve in place just for the wiring to the sender, I was going to remove it but I couldn't figure out which wire went where so I just left it. And yes I sealed up the unused lines to the rear tank very good, love the Permatex aviation sealer.

 

[franklin2]

This works well also to seal against diesel and gasoline.

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[Mulochico]

Mulochinco, Thanks for the kudos, I've found that I can accomplish a lot with a mig, drill press, drill, grinder ect. Our setup looks very similar, both use 1/2 inch hose, my fittings are 1/4 inch ID looks like yours is probably larger ID. Can't see how your sealing is actually done but it looks to be working good as it all looks pretty weathered and time tested. Yes, fuel and return only goes to front tank, I replaced rollover valves and ran the new vent lines along the fill spout and it terminates as high as I could get it inside the fill door, I just drilled a hole thru the plastic box that house the fuel filler cap. I opted not to put a valve in mine for simplicity. I cut the wires to the rear sending unit when removing the tank and didn't bother repairing as I only plan on using the front sending unit (didn't want to spend money on another sender) I did end up leaving the selector valve in place just for the wiring to the sender, I was going to remove it but I couldn't figure out which wire went where so I just left it. And yes I sealed up the unused lines to the rear tank very good, love the Permatex aviation sealer.

My sealing was jb weld. Didn't have a better way and figured if it didn't work I would do the Bronco tank on the rear. It's been 10+ and no problems but a tightening the valve. I'm very happy and, as you wrote earlier, no more thinking of a transfer valve, etc. I'm very old school, simple and working over fancy and potentially problematic. I do enjoy my idi.

 

[Ohiogoldfever]

Thanks for the details fellas. I plan to swap out both tanks on my build with two brand new tanks I got with a parts truck. I plan to do a large cross over line and up date the vents. Being the tanks are new I doubt I should have much issue drilling and installing fittings.

I dig the screens, good thinking. Hell I just installed a brand new fuel system from to back on one of my jeeps just for the idle circuit to plug up after the first 50 miles. Brand new ain’t what it used to be.