Adding a secondary fuel tank
 

So my car is a 1995 acura integra sedan. I bought this car mainly as a back up to my cobalt. It gets pretty decent mpg so far but I thought about adding a secondary fuel tank to the car. I mean there isn't really a great reason for doing so but I thought why not. Other than getting a fuel tank to go into the trunk. What else would I need for this? Would I need a secondary fuel pump? My idea is to have a second gas cap so I can put fuel just in this tank, then flip a switch and a small fuel pump pumps fuel from the back up tank into the secondary one. I would have to run a line from the second tank to the main one. I'm all up for advice on this matter. Thanks.

Not sure that this is really the best idea. Unless you are hwy driving, you will loose FE and, really, if you are on the hwy, can you go 5 hrs without a break? I start to kill people.

how well it loose fuel economy?

Fill the back of your car with extra weight? Not sure how that works, my guess is it decreases FE in city driving. Newtonian physics....

oh well I'm not worried about the extra weight. What are the legalities of doing that cause I read this
Install an Auxiliary fuel tank on your truck

ok, well you got me there. Are you worried about FE at all? I understand the weight doesnt bother you, but then why?

eh just longer range really, it would save me from having to fill up at the pumps more often, idk I wouldn't mind that. Just one large fill up at the beginning of the month then I wouldn't have to fill up for a month. It it legal though?

legal? possible, safe, eh

what do you mean?

If you really want to do something like this then getting a fuel tank that fits in the spare tire well like is used for waste veggie oil in diesel cars is most likely going to be the safe and easy way to go, but the cost and time you are going to invest in adding this 2nd fuel tank, you would come out ahead by doing other things that would get you better mileage, or if it's the time then the added time to install a system like this compared to the time spent at gas stations is going to take years to brake even.

Inevitably I'd fill up at the beginning of that long trip and gas would be cheaper the whole rest of the way. :rolleyes: 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.

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

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.

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.

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

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

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.

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? :rolleyes:
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.

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!

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.

your f150 has dual tanks mounted under the vehicle. It doesnt have them in the truck, and I think we know that the OP wasnt looking to reduce the size of his primary tank, but to enlarge it. I would be going on a limb here, but I believe there is not any room under this car for an additional tank. If he split the size in half, and put two in place, he would have accomplished nothing. once again, "silly" justifications for stupid ideas.

OP, put the tank in so that you dont have to stop for fuel more than once a month.

If you're going to do this, buy a good quality racing fuel cell which is designed to be in the passenger compartment. You might regret a cheap plastic boat tank in a rear end collision. And I'd really want an external filler neck, you know some gasoline will drip from the nozzle into the trunk.

i know this is old but....better then starting a new one.....

ive carred cans of fuel so i can drive thru a state, saving 0.20 or 0.30 a gal.:thumbup:
was pulling a trailer and had the cans back there.


ive figurd if i did it agen id have a tank with one line to the main tank with say a ball valve.
drive 4+ hours stop at a rest area, open the valve, eat, stretch, and keep driving. it would run in to the tank for the 20ish min im there and its ready to go.

no added pump, gage or wiring :)

I would buy a jerry can or cans instead.

I see gas being much more possible trouble than diesel/veggie oil!

I would want it for long distances/values as Bestclimb has well stated.

I had a plastic tank custom built to fit the spare tire depression perfectly in a Vw diesel wagon.

I live in an area of much higher fuel costs. As per Bestclimb; I can fillup both tanks in mid-USA once, and get all the way home!

Spare tire depressions are low, and close to stock tanks, so simple gravity valves to original tank pretty easy; and veh. handling changes are minimum. (my tank holds between 11-12 gallons) Yes, the spare tire is up elsewhere, but for interstate type trips where hrs. per day is a constant fluid motion, the tinch of extra weight is far outweighed by your freedom in being more self contained, paying for fuel where it is a fair price.

In the future; it may be difficult to get any fuel at any price!

That's why I'm high on older simplist diesels. You have MANY options for fuel, some of which you can make yourself!

larrybuck, Where did you get your plastic spare wheel well tank? I'm looking at going the smaller main tank route. My 5 mile commute 4 days a week means filling up the 12 gallon tank every 2 months. So for the first month I'm carring around 35lbs of fuel I won't need for several weeks. So my plan is to get 5-6 gallon spare wheel well tank and remove the main tank. 35lbs of fuel and 10-20 lbs of steel in the 12 gallon tank weight savings for my 22 stop lights in 5 miles.

I drove from Racine, Wisconsin to Joplin, Missouri straight through only stopping for food and gas. That was about 12 1/2 hours total.

...in July 1966, I drove 30 hours straight from Memphis, TN to Yuma, AZ, a distance of ~1,800 miles, stopping only for gasoline and potty stops.

I once drove from central Alaska to New Mexico (near the Mexican border) in about 4, 16 hour days, roughly 4000 miles. Gas-n-go until crashing in a hotel. I'm still sane. :p

One point for the original poster, I have a 36 gallon tank in my truck. I rarely let it go empty because it's annoying to have to use the credit card twice at the pump. Every gasoline pump I've gone to has a limit, usually $100, then the pump turns off.

To busy paws: I had a friend custom build it from scratch. I started w a flat plastic sheet about 1/4" thick; 4X6 feet. He cut out a bottom, top, and 2 or 3 layers of bands height wise, and slowly plastic welded it altogether. It was time consuming, and much ventilation (outside) is needed, as plastic smoke is a little nasty. I'm sorry that I can't remember the exact name of the particular type of plastic I used; but if you explain to the plastic supply store what you are trying to do, they will point you to the right type!

I admittingly, am not super hands on; at $20. per hr., I paid my friend about $200. I started w a weeny powered welder at first; thats what ran into so many hrs.

The stock tank on my VW is plastic; strong, lightweight, will never rust; so I figured a 2nd tank built in same to be good.

So mine is a one off; that I am proud to own even if I didn't make it myself. For precautions, we put a layer of plastic sheeting between the tank and spare depression to prevent any rubbing. He also added a small metal bracket on top of the tank, so a holder could be attached to just the upper side in one place on the edge of the depression. This was to prevent any TWISTING of the tank that might be done in emergency driving. This method does not really have to be any more sophisticated than like the screws used to keep a light globe in position in your home.

I really like the stock depressions for the low center of gravity, a just a natural safety feeling. If you are only going to build a 5-6 gallon one, you could build it low enough to still have a spare halfway in the depression above it if you choose; although especially if this is a gasoline situation for you and not diesel; for obvious reasons, I'd reccomend some kind of padding between.

For possible emergency driving, I think a tank should be near the circumforance of the depression, as opposed to something box like that might need lots of spacers, or other ideas to keep it from sliding around. I suppose something like the battery hold-downs (universal) would do; but it is nice to have something that looks professional.

Again, my app was diesel, so my venting concerns were min., so please keep that in mind for your safety! The color of the sheet I got was white; I thought a good color for keeping heat down.

In my app., I had heated lines running under the car toward the eng. compartment, as I was trying to do Veggie!
I didn't get far enough to figure out a gauge sender or any of that. When my friend finished the tank; before I could even say a word, he WHALED on the tank w a hammer showing me how strong it was!

If you buy a good quality welder, and since you are only looking for 5-6 gallons, whether you choose to try it yourself, or pay another, enough people are looking for work that you could probably find a Mobile Mechanic type guy in your local Craig's List that would be reasonable dollars per hr. wise.

Racing type fuel cells are very expensive I think in comparison. Just be safe, as again I'm mostly concerned about proper venting for a gas app.


To Joenavy85: I think I enjoy driving about the same # of hrs. per day as you do. I do try to break it up a little w basketball shooting, or walking to keep the sitting stiffness down.

To Old Teleman: I surmise that all those miles and hrs. were done when you were a wee bit younger. If I'm VERY comfortable in my alignment posture wise w steering wheel, correct distance of arms out; I love up to 13 hrs. a day at 50-55 mph.
I tried 22 hrs. on a motorcycle when much younger... felt tired enough to feel like I was on drugs or something.. the enjoyment factor is gone at that point for me.

At 30 yrs. old, I could do 800-950 miles per day at 55mph. for 4 days in a row, but now, unless I ride alot to TRAIN my butt, 500 miles is long, and 250-300 at 50-55mph. I enjoy much more. Unless you have the perfect custom seat, or are much shorter, I don't see how these guys did these Ironman 1,000 miles a day back to back to back trips, until I just now realized........... I've been an Ecomodder for yrs., because I never cruised above 55mph.!!!! Those miles would go a lot faster at 80mph., or something, the adrenaline rush, and looking for cops all the time would probably keep them hyped up!

In July I'll be driving from Illinois to California over a 4 day period, starting on a friday afternoon and ending monday morning. I'll be covering ~2250 Miles during that time, thankfully my girlfriend will be going with me and will be sharing the driving duties with me, 3 hours shift, 2 shifts a day, until we get there.

I agree with Ryland. Through research, practice and q&a with all of us here on the site, you'll be well on your way to stopping at the pumps less. Although I admire your fervor, I think you'd be disappointed with the results of your arduous labor.

I know you're new to the community, have you read all of the main articles about hypermiling, ecomodding and the like?

all the best