Adding a secondary fuel tank

[Frank Lee]

Inevitably I'd fill up at the beginning of that long trip and gas would be cheaper the whole rest of the way. I've found that I gotta stop for leg stretching breaks, or breaks of some sort, before the car needs filling.

Anyway, I've plumbed into a gas can in the trunk before... then I upgraded to a snowmobile gas tank (had a gauge on it, and was much bigger). That was just on old carb'd stuff. I see two ways to go about it: transfer pump into the primary tank, or a separate but equal tank w/pump- heck, that might not even need a valve or check valve if the pump assys have check valves in them. I think the second method is how F150 dual tanks are rigged, but I've never studied them.

I'd love to have dual tanks on my car. I could keep E85 in one and E10 in the other. And/or have a primary tank sized for reasonable fill intervals for around town use- say, a 5 gallon primary tank with a 10 gallon secondary tank that I'd fill for long trips; that would maybe save 50 lbs from having a full 15 gallon tank, and the small tank wouldn't have all that sloshing going on all the time.

Maybe the secondary tank could have a quick-connect like outboard boat motors have, so that it's kept in the garage until needed, then bungeed down in the trunk when wanted.

[SentraSE-R]

Now, that's thinking outside the box. Good ideas, Frank.

[autoteach]

No one sees the problem with this? It is neither safe (frank hates nanny's), cost saving, FE, nor space saving. The time to install will take more than what you will save by not stopping for fuel. There is no fire wall between the trunk and people seats. Venting would be in the trunk (bomb). Weight would wreck FE. It would cost you money and wouldnt improve FE. You would have a tank in your trunk, and logic tells you that when you would want the capacity (long trip) you might also want to pack some stuff. Good luck, I wouldnt do it.

[bestclimb]

Aux ank would be above cars tank, let gravity do the work for you. Make sure the car's fuel tank is nearly empty then crack a valve to let the fuel flow into the main tank. could be electric valve, or mechanical with a push pull choke cable affair to move it. If the tank is insulated from physical damage during an accident, and securely mounted it would be safe enough.

I have thought about doing a mod such as this to one of my vehicles for a couple reasons.
1 winter road trips extra gas can be helpful. Some places aint opened year round and I figure I could get most the way through Canada without stopping.

2 while stopping at night in winter can be an issue in regards to preheating not being available (at 50 below you gonna count on being able to restart with out plugging in?) so extra idle time could be handy. A portable generator to run heaters (or gas stove under the oil pan [I have done this]), and bringing in the car's battery would eliminate the need to idle all night.

3 Fuel may be hard to get during the zombie apocalypse....or what ever, so added range may be handy.

4 For highway travel being able to have more range may put you into territory where fuel is cheaper.

As far as mileage goes, on the highway extra weight won't hurt much as you are not on and off the binders much.

[autoteach]

Ok, I saw Mad Max, and that ended in the 80's.

[camopaint0707]

yeah i guess its not the best idea in the world, thanks for the input

[Frank Lee]

I dunno, do it right and it'll be OK. For example, I have a '68 Chev pickup... the gas tank is pretty much vertical and it lives right behind the seat, about 3" away from the driver and passenger. No extra "firewall", no nothin'. Of course it is vented out (good point). I bring that one up because that is NOT the Chev PU that got the bad rap for dangerous gas tanks- that was the next model with sidesaddle tanks and incidently I understand they are statistically no worse than anything else.

For me and the way I laid it out, it would be cost saving to be able to run E85 year around. And in some small probably immeasureable way, if I was to reduce primary tank size yadda yadda there may be an fe gain from the weight reduction and perhaps even less fuming of gas in the tank from less sloshing.

No one sees the problem with this? It is neither safe (frank hates nanny's), cost saving, FE, nor space saving. The time to install will take more than what you will save by not stopping for fuel. There is no fire wall between the trunk and people seats. Venting would be in the trunk (bomb). Weight would wreck FE. It would cost you money and wouldnt improve FE. You would have a tank in your trunk, and logic tells you that when you would want the capacity (long trip) you might also want to pack some stuff. Good luck, I wouldnt do it.

Point by point:

I don't see anything inherently unsafe about the concept.
It wouldn't save cost except if: you have an E85 situation like mine and/or you use gasbuddy to check prices on your route so you know where the optimal place to fill is.
It wouldn't save fe unless you reduce primary tank size and weight... and even then...
It needn't suck up so much trunk space as to render the trunk less useful. There may even be another spot to tuck it- under floor, under trunk floor, under seat, under hood, who knows?
See above re: lack of firewall- big deal.
If tank is in any interior compartment... really, is running a vent hose outside, or tee'd into the vapor recovery system an insurmountable challenge?
Weight- another 5 gallons, another 30 lbs; another 10 g, another 60 lbs- hardly enough to "wreck" fe.
And finally, if you do it like I would (Master Scrounger/Repurposer) the money wouldn't be an object, or an obstacle.

[autoteach]

Originally Posted by Frank Lee

Weight- another 5 gallons, another 30 lbs; another 10 g, another 60 lbs- hardly enough to "wreck" fe.
And finally, if you do it like I would (Master Scrounger/Repurposer) the money wouldn't be an object, or an obstacle.

On these two points, Frank, I would like to point on some really important things. First, you have a weightless tank and pumping system, or hoses, or however you will do it. Even the bungee cord you would use might just have some mass. And, I figured that there wouldnt necessarily be money involved in the parts, as you would most likely use something you already had laying around (fishing boat tank), but... HOW MUCH TIME? Of course, not much. These type of "use stupidity to justify insanity" scenarios of "Not dying for 68 million years, by odds) reminds me of twins I had as students. I told them that if they would like to get their lawn mower going that they would have to bring in some gasoline of their own. The next day they came to class with a pint canning jar filled with glass. I guess they lived, and they didnt get suspended, and no one got hurt. 0 out of 1, so in all the lifetimes of every human... Still a bad idea.

[SoobieOut]

I did see an extra fuel tank in the trunk of a Mercedes 240D one time. The 240D was a diesel with very little power to begin with. Add a 50 gallon diesel tank in the trunk and it was a slug. 0-60 in 5 minutes!

[Frank Lee]

I did think of the weight of tank(s) but I was thinking of the reduced size primary tank (weight savings) and not only that, small tanks like that don't weigh much anyway, but since I was not going to go out and weigh any tanks before posting, I didn't include any estimate for that. Throw another 30 lbs in there then and calc the fe destruction.

BTW, we went through that little odds thing already didn't we? What I did is a legit way of presentation. If you think dual tanks are inherently stupid/dangerous, maybe you should direct your ire towards Ford Motor Co., as my F150 has them stock.