Additional Chevy saddle tanks on Suburban?

pappawheely

Autonomous4X4
I am designing a dual tank system on my truck so I've done some research on this. Gravity flow has drawbacks like Rayra says. If you lose a fuel line, the tank will drain out, that's dangerous. You can't always count on gravity feeding the main tank unless you have it much lower than the feed tank or tanks. You also have to think about the venting system. Each tank will need to tie into the same venting system or have it's own dedicated system. You don't want to have a situation where one tank siphons from the other through the vent line. You also need enough back pressure to shut the fuel nozzle off when filling. You don't want fuel shooting out of the vent hose. The factory FORD dual tank systems have dedicated pumps in both tanks. I have decided to use one tank for storage and transfer that fuel to the main tank with a pump. in a worse case situation, I can swap the supply line to the engine from one tank to the other.
 

rayra

Expedition Leader
And that introduces another point, from an 'expedition' perspective. two tanks, two systems, redundancy. Build a setup with redundancy and options, rather than just a bigger basket for more eggs.

Especially easy to do if you go with a stock tank with all its attachments and its own fuel pump.

My old pickup has two tanks but one mechanical fuel pump. The dash switch powers a solenoid on a valve to switch between source tanks. Ironically I've never considered that in the now 30yrs I've had and driven that truck. 350k mi. The switch crapped out, but never that switching valve. And I can't imagine where I'd find a replacement. I imagine I'd either plumb a manual valve or switch to two electric pumps, one on each tank and a toggle switch to pick between them.

Ever since I got caught out by the Northridge earthquake 22yrs ago, both tanks dry (and lacking a lot of other things AND with my freshly busted knee in a brace, thanks to a skiing accident), I have always kept one tank full. When I'd run one near dry, I'd switch tanks and stop before I got home to fill up the empty. I've always had at least one tank full in it ever since. Maybe all those years of alternating are what has kept my fuel system in that truck trouble free all these years and miles.

/just jinxed it, I'm sure
 
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pappawheely

Autonomous4X4
And that introduces another point, from an 'expedition' perspective. two tanks, two systems, redundancy. Build a setup with redundancy and options, rather than just a bigger basket for more eggs.

Especially easy to do if you go with a stock tank with all its attachments and its own fuel pump.

My old pickup has two tanks but one mechanical fuel pump. The dash switch powers a solenoid on a valve to switch between source tanks. Ironically I've never considered that in the now 30yrs I've had and driven that truck. 350k mi. The switch crapped out, but never that switching valve. And I can't imagine where I'd find a replacement. I imagine I'd either plumb a manual valve or switch to two electric pumps, one on each tank and a toggle switch to pick between them.

Ever since I got caught out by the Northridge earthquake 22yrs ago, both tanks dry (and lacking a lot of other things AND with my freshly busted knee in a brace, thanks to a skiing accident), I have always kept one tank full. When I'd run one near dry, I'd switch tanks and stop before I got home to fill up the empty. I've always had at least one tank full in it ever since. Maybe all those years of alternating are what has kept my fuel system in that truck trouble free all these years and miles.

/just jinxed it, I'm sure
That is the system I am building. My reason was the in-tank pumps. If I am in BFE and an in-tank pump goes out, I'm walking. I decided to switch to external pumps. That's when the snowball started rolling. :coffeedrink:
 

rayra

Expedition Leader
I'm liking that idea. Buy two electric fuel pumps, mount them side by side on a frame rail, plumb and wire one with a enough slack to allow swapping the connections to the other pump. Cap and wrap that idle pump against future need. Maybe swap connections on a periodic basis. Small investment on a critical failure point.
 

Texan1983

Adventurer
im more of a simple plan... while I like redundancy I just can't do two high flow pumps.

im using a poly jeep pickup 18 gallon tank mounted in the old spare tire spot, with it's own transfer pump to the main tank. Extra gauge and switch run in the cab to transfer on the fly.
 

nitro_rat

Lunchbox Lockers
If you look at a squarebody truck you'll notice that the seat sits on a hump. That hump is to clear the gas tank. The floor is flat on a burb or k5 and that's why they have the tank out back between the frame rails. A k5 25 or 30 gallon tank will fit a SWB truck and the bigger burb 40 gallon will fit a LWB.
 

nitro_rat

Lunchbox Lockers
So the floor on burb being flat precludes the 25 gallon tanks from fitting?
It would take major floor mods to fit truck saddle tanks in a squarebody Suburban, yes. I have seen a GMT400 Sub with a pickup gas tank fitted in lieu of the rear mount so I guess a dual tank situation could work in those.

For ultimate range a long bed square can be easily fitted with triple tanks for almost 100 gallons of fuel...
 

dejablu311

Observer
Well that's a bummer. I am looking for a "budget" auxiliary tank option and there is quit a bit of room between the rockers and the frame. Those saddle tanks would have been perfect.
 
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