Auxiliary fuel tank and gravity vs electronic pump

I have a 40 gallon RDS tank with gravity feed. I have a manual shut off valve and also a electric solenoid that controls the flow. The electric valve has a switch in cab and is wired to a "ignition on" circuit so it closes when the truck is shut off or the switch is in off position. The valve I use is this one I bought at Amazon.
Link for valve at Amazon

3/8" NPT Electric Auxiliary Aux Fuel Tank Valve for Trucks Diesel Gasoline 12-Volt DC EHCOSMART COIL

Scooby, thanks for the personal stories. But a simple check valve on the filler hose above the inlet for the aux valve tank ( just like the simple “kits” that have been for sale forever) and a requisite valve at the slip tank just works.
Regardless of all the introspection and “theories.”

Sport45 wrote:

JRscooby wrote:
I can see how that would work. OTOH, the valve in toilet starts to leak, water drains thru the overflow, overfills bowl, and down drain. Can waste a lot of water but that is the only harm unless you have to pay a plumber to replace it.
A similar system is the float/needle seat system in a carburetor. When that leaks gas can get on top of engine, but it also dumps into the engine stops it from running right (if at all). Fuel pump stops putting gas to carb. Fire is a possibility, but most likely expense is carb rebuild.
What happens if you park the truck with a leaking float valve.
BTW, in my lifetime I have replaced over 100 toilet tank valves, and rebuilt even more carburetors. Failure is not a far-fetched idea.

If it's overflowing I'll likely smell the diesel when I get out of the truck, notice the spots of fuel blown up on the back of the truck (yes, I know what a fluid leak does to a moving vehicle) or see the puddle under the truck. Just like other failures I've dealt with I'll close the manual valve until I get a chance to repair or replace the float valve. I won't be losing any sleep waiting for the failure to happen though.

I'm sure if you where near the vehicle you would notice the leak. But I sometimes turn my donkey to my pickup, don't look at it for hours. Park over night, with it dripping a quart a hour, would not make you popular in any campground.
I would think a valve that shuts off with ING switch would be a real good idea.

JRscooby wrote:
I can see how that would work. OTOH, the valve in toilet starts to leak, water drains thru the overflow, overfills bowl, and down drain. Can waste a lot of water but that is the only harm unless you have to pay a plumber to replace it.
A similar system is the float/needle seat system in a carburetor. When that leaks gas can get on top of engine, but it also dumps into the engine stops it from running right (if at all). Fuel pump stops putting gas to carb. Fire is a possibility, but most likely expense is carb rebuild.
What happens if you park the truck with a leaking float valve.
BTW, in my lifetime I have replaced over 100 toilet tank valves, and rebuilt even more carburetors. Failure is not a far-fetched idea.

If it's overflowing I'll likely smell the diesel when I get out of the truck, notice the spots of fuel blown up on the back of the truck (yes, I know what a fluid leak does to a moving vehicle) or see the puddle under the truck. Just like other failures I've dealt with I'll close the manual valve until I get a chance to repair or replace the float valve. I won't be losing any sleep waiting for the failure to happen though.

Sport45 wrote:

JRscooby wrote:
I'm hard of understanding here. If you have a line from 1 tank down to another, the fuel will flow. And if the level of fuel is above the fill neck of the lower tank, or any vent, what will stop fuel from coming out the vent?

Mine has a float valve where it ties into the main tank fuel fill line. It doesn’t let any diesel in once the tank is full. I suppose it’s similar to the valve that stops water flow once your toilet tank is full.

I can see how that would work. OTOH, the valve in toilet starts to leak, water drains thru the overflow, overfills bowl, and down drain. Can waste a lot of water but that is the only harm unless you have to pay a plumber to replace it.
A similar system is the float/needle seat system in a carburetor. When that leaks gas can get on top of engine, but it also dumps into the engine stops it from running right (if at all). Fuel pump stops putting gas to carb. Fire is a possibility, but most likely expense is carb rebuild.
What happens if you park the truck with a leaking float valve.
BTW, in my lifetime I have replaced over 100 toilet tank valves, and rebuilt even more carburetors. Failure is not a far-fetched idea.

hotpepperkid wrote:


I want to hear the rest of the story.

In that area, most of the owners of small farms have some kind of job in town. We where on a main road into metro area, where the farmers likely to pass by commuting.
Most of the farmer have tanks set up, get fuel delivered for use in ag equipment. The sellers of that fuel do not collect the road taxes, so the fuel is cheaper. But to mark the fuel as non-taxed, the sellers are required to add dye to the fuel. A percentage of the farmers pump the dyed fuel in pickups. So on occasion the state tax collectors join the other LEOs and sample fuel as part of safety inspection.
As for my other infractions? MFIC told me to be right next trip thru. Rode home with other hands, used some chain and boomers to mount another transfer tank to a utility trailer, hauled it back and forth with my El Camino.

JRscooby wrote:

dedmiston wrote:

Grit dog wrote:

Lwiddis wrote:
Aren’t gravity fed gasoline tanks illegal?

Aren’t you trying to start an argument, or just typical passive aggressive response?

It's just Lwiddis being Lwiddis.

Sorry. I do not see anything in the OP that tells what fuel the pickup uses.
And it is a fact there are a lot of regulations, (impact protection, vaper recovery, whatever) that apply to gasoline tanks in vehicles. Most tanks sold to mount in bed are advertised diesel only to avoid the regulation.
For many, is it legal is a valid question.

Of topic, but kinda funny.
Contractor I did a lot of work for had a few weeks work, about 60 miles from home. I decided to leave 3 trucks on site, just sneak 1 into town every day for fuel. Contractor could not fuel all equipment on job with the transfer tank mounted on his truck, so we strapped a tank down in my tool truck.
One morning, I ran into a DOT check on my way in. When stopped, had 3 things on my mind; 1, likely over my licensed weight limit. 2, real close to limit on licensed distance from home. And 3, the straps holding that tank did not have a load limit label. LEOs 2nd question, behind DL, registration, and insurance, was "What kind of fuel in tank?" Now I'm not thinking about the step by his knees when I said "Dyed, off road diesel" He was mad when he stuck his wand in my gas tank, and the plastic dissolved. At the time I had a 460 in that old F500.

I want to hear the rest of the story.

JRscooby wrote:
I'm hard of understanding here. If you have a line from 1 tank down to another, the fuel will flow. And if the level of fuel is above the fill neck of the lower tank, or any vent, what will stop fuel from coming out the vent?

Mine has a float valve where it ties into the main tank fuel fill line. It doesn’t let any diesel in once the tank is full. I suppose it’s similar to the valve that stops water flow once your toilet tank is full.

I'm hard of understanding here. If you have a line from 1 tank down to another, the fuel will flow. And if the level of fuel is above the fill neck of the lower tank, or any vent, what will stop fuel from coming out the vent?

Just drinking bleach here; Does the pump in tank send more fuel to injector pump then the engine will use, then extra returned to tank? If so, put a tee in the supply line between tank and injector pump. (or filter) On the leg of the tee that goes to factory tank put a normally open solenoid valve. The side going to engine, no change. The other leg, a check valve strong enough to hold against factory pump pressure. Have the pump by add-on tank feed thru the check valve. A switch on dash cuts power to factory pump, closes the valve in supply line, turns on added pump, and a light near fuel gauge. Fuel would feed thru check valve to engine, and the extra returned to OEM tank. As you drive the fuel level shown on factory gauge would rise, near full, switch back to OEM function

Thank you everyone for your input, I went with a Lund 37 gallon steel tank and a gravity fed system with a shutoff valve for over flow! It would have been cool to utilize my upfitter switches but I’ll probably use them for the light bar and winch set up I’ll be doing later

thomas201 wrote:
When I had diesel, I used gravity feed. With gas, I have to pump. I would not pump diesel, because if you leave the pump on it will have to go somewhere after the truck tank is full. So, if you pump, you need a return line to the deck tank. Just saying.

Diesel or gas you overfill the tank it's going somewhere. A return line isn't needed. The trick is to have a reminder such as a buzzer or light in the cab to remind you the pump is on. If one of those doesn't do the trick well, "You Can't Fix Stupid"