2005+ Tacoma: is aux fuel tank opposite existing fuel tank possible?

[Switch]

I posted this question over on TTORA but that site is more rock crawler rather than expedition oriented so I'm hoping to get a better response here:

The idea is to move the existing muffler to allow for an aux fuel tank. I don't want a tank in the spare tire location for various reasons.

It seems that it might be possible to shape a custom tank to leave room for the exhaust pipe where it is adjacent to the drive shaft but there is bonus fuel capacity if the exhaust pipe be run between the drive shaft and body as much as possible.

The specific questions I've been researching are:
1) How close the pipe can be to the tanks and drive shaft? How much can heat sheilding mitigate this?

2) If muffler is moved forward. Is that going to result in heat blowing over the tank and causing problems. How much can heat sheilding mitigate this?

3) If the muffler is moved backward, does it leave enough space for a tank big enough to warrant the price tag.

4) How expensive the whole tamale would turn out.

5) Can two smaller mufflers be placed before the y pipe? (bonus eliminates that stupid low hanging crossover pipe).

6) Would this degrade performance?

7) Is it leagal? Answer: In many states, no.

8) How to implement something like this:http://pollak.thomasnet.com/viewitem...lve?&forward=1 for maximum integration to the exisiting fuel system.



best photo I've been able to find of this area:

 

[washington taco]

I was thinking something similar on my 2000 Taco. I would remove the stock muffler and have new exhaust bent from the cat back too parellel the driveline then have a smaller muffler installed in the spare tire area. Then install a stock tank in the old muffler area.

 

[HMR]

:lurk:

 

[gearbox]

Thanks for starting the discussion. Popcorn for me as well. I don't have much to contribute, I just want the same thing down the road. :lurk:

So far I had planned to expect only to be able to put a suzuki tank in place of the spare.

 

[Dave Bennett]

In my opinion, no. There's a reason that the OEM has this layout.

Best aux fuel tank location IMHO is where the factory spare resides. Perfect spot, nothing in the way, and the filler neck can be combined with the OEM fuel door/neck like they do on some 80 Series LC's.

I'm considering something like what Irbis did with this Isuzu tank

.02

 

[ntsqd]

Some intuitive thoughts on the idea:

The effectiveness of the heat shielding will be economics. The more that you spend (on quality & not hype), the more effective that it will be and the closer gaps that you can run.
What you might do is try hanging some of the proposed heat shielding as close to the exhaust where you expect to need it. Then hang a piece of metal of the same type as the part you want to shield with the same expected gap from the heat shield. Paint some stripes on this part with some Tempilaq temperature indicating paint. Then you can test how effective that proposal is in the real world. One guy that I know uses plain old thick type cookie sheets to shield his floor from exhaust heat.

In KA the rule is that Emissions related mods restrictions start at the first sensor that might have any effect or impact on emissions and end at the last such sensor. So if you have an O2 sensor after the cat behind it will be the furthest forward that you can disturb without an E.O. stickered part.
YMMV.

If the tank isn't going to be in the spare location, will the spare be there? If not, why not move the muffler into a portion of this area?

Only the drive shaft U-Joints are going to care about temperature, but keep in mind metal's excellent thermal conductance.

 

[slooowr6]

I did some research on adding a aux tank to Taco. Like TACODOC said the best place is the stock spare tire location. Just be aware the Taco/FJ/4Runner all use the same emission s check system for gas tank leak. There is a LONG thread on fj crusier forum about Man-A-Fre FJ aux tank cause check engine light to come on and throw codes realated to emissions system error. It looks like these truck have a leak test system, it'll create a vacuum (negative pressure) in the gas tank to check if there is a leak. If it can't reach the preset vacuum you'll get a check engine light.

 

[ntsqd]

Most late models will trip the CEL if you don't tighten the fuel filler cap.

 

[HMR]

slooowr6- Excellent point regarding the vacuum issue. I hadn't considered that.

My biggest gripe (only gripe?) with my Tacoma is the limited range per tank. ~300 miles on the HWY is a little short for the kind of trips we normally take. I'll happily spend the necessary $$$ if there's a reliable way to get another 150-200 miles from an aux tank. I carry 2, 5 gallon cans in the bed for offroad use but it would be simpler/safer, IMO, to have an aux tank.

 

[HMR]

FWIW- CORAX gave me some good advice here.

I still like the idea of attaching something like this in the bed and having it gravity fill the main tank via the stock filler tube.

I've been researching electronic fuel valves in the hopes that I'll find something that could be safely activated from the cab. My idea is to wait for the stock tank to get "low" then flip the switch, open the valve, and have the aux tank refill the stock tank with an additional 10-15 gallons. Once the aux tank is empty the valve would be closed. If the valve seals airtight it shouldn't cause any computer or emissions problems, right?

 

[slooowr6]

FWIW- CORAX gave me some good advice here.

I still like the idea of attaching something like this in the bed and having it gravity fill the main tank via the stock filler tube.

I've been researching electronic fuel valves in the hopes that I'll find something that could be safely activated from the cab. My idea is to wait for the stock tank to get "low" then flip the switch, open the valve, and have the aux tank refill the stock tank with an additional 10-15 gallons. Once the aux tank is empty the valve would be closed. If the valve seals airtight it shouldn't cause any computer or emissions problems, right?

Yep, it's should work prefectly. The ECS will not see the aux at all if there is a air tight valve in between.

I really want a aux tank as well, my rang is around 300 miles too. I need to look for gas every 250 miles.

The thread on FJ cruiser one of the poster has a Toyota tech subscription. He post the emission system diagram and function flow. The system is pretty interesting. In short, the system will use vacuum to check for leak after the truck has been park for x amount of time, if the 1st test failed, the system will wait y amount of time then re-run the test again. I don't remember the exact time so I use x and y.
After I read through the diagram and function flow.

 

[java]

FWIW- CORAX gave me some good advice here.

I still like the idea of attaching something like this in the bed and having it gravity fill the main tank via the stock filler tube.

I've been researching electronic fuel valves in the hopes that I'll find something that could be safely activated from the cab. My idea is to wait for the stock tank to get "low" then flip the switch, open the valve, and have the aux tank refill the stock tank with an additional 10-15 gallons. Once the aux tank is empty the valve would be closed. If the valve seals airtight it shouldn't cause any computer or emissions problems, right?

older f250's had dual tanks, i used the fuel tank switch from one of those for a project, simple solenoid switch and it was fairly cheap. sounds like it could work for this type of system.

 

[Dave Bennett]

FWIW- CORAX gave me some good advice here.

I still like the idea of attaching something like this in the bed and having it gravity fill the main tank via the stock filler tube.

I'd rather keep that weight low between the framerails

 

[HMR]

I'd rather keep that weight low between the framerails

I agree. That would be the ideal location.

Some of the problems are:
-Where to put it? (spare tire area is questionable with stock bumper and probably won't work at all with a high clearance version)
-Requires a custom-built or modified tank.
-How to plumb it to avoid the vacuum issue mentioned by Slooowr6?

I'm not too concerned about the weight as 70-105lbs (10-15gals) mounted to the front of the bed, at floor level, equals MUCH less of a lever arm (torque) than something like a single jerry can or hi-lift mounted on a roof rack.

 

[washington taco]

What about some of the tanks made for drag racing? I think manufacturd by Jazz. NHRA safety approved, plastic, and numerous sizes.