Replace original gas tank

beerman5050 · December 14, 2006

Hi all.

New to this forum.

I have a 2004 GMC Sierra extended cab 4x4 1500 pickup with a short bed (6.5') and a 5.3L gas engine. Has you probaly know it has a 26 gallon tank which is way to small for me, especially when hauling my fifth wheel. I have been researching for a month or so now on installing an extra gas tank or replacing the OEM tank. I have checked with a few auxiliary tank manufactures, such as Transfer Flow, etc, but they do not make anything for my truck.

I am looking at replacing the 26 gallon tank with GM's 36 gallon tank. I'm not sure if this can be done and I have checked with my dealer and he wasn't sure either.

Does anyone here know if this can be done and if it would work ok?

I have read some of the posts here and it seems as if there may be some problems but I want to be sure and would like to know if there are any problems, what they are.

Thanks

95Sierra2500 · December 14, 2006

I wouldn't think so as the larger tank is usually designed to only fit under the long-box trucks. I think it has something to do with they don't want all that fuel sitting directly under the passenger compartment. However, if it will actually fit with some modifications I don't really know. You could get one of those big fuel tanks that sits in the front part of your box, however, and link it to your other fuel tank. However, you would have to redo the vent system as well so the fuel wouldn't leak out all over the ground.

beerman5050 · December 14, 2006

I have check around and can't find a tank for this truck that you can use in the bed. Not being made for this truck as far as I can find out. I can get my hands on a 36 gallon GM tank but I need to know for sure if it will fit before I lay out my money. Any suggestions?

Tucson_02Silverado · December 14, 2006

This is popular with the fifth'ers and diesel haulers.

Transfer Flow

beerman5050 · December 14, 2006

I have already checked with Transfer Flow and others and they do not have any tank, in bed or otherwise, for my gas truck. I was told that there are emission problems, check engine light comes on, with the 2004 and up GM trucks when you use an in bed tank. I'm hoping that I will be able to replace my 26 gallon tank with the 36 gallon GM tank. Can anyone tell me for sure if this can be done? This is my last hope unless someone can come up with another solution.

Ranger · December 14, 2006

Look up something called Fuel Safe. They make big gas tanks that usually go on rock crawlers, Baja desert runners, etc. They look pretty good too.

beerman5050 · December 15, 2006

I have sent an email to Fuel Safe to see if they can help me. In the meantime I still would like to know if I can replace my 26 gallon GM gas tank with a 36 gallon GM gas tank without any modifications. Does anybody know if this can be done? This is the option I would like to go with if it is possible as it will increase my fuel capacity by 10 gallons which would be enough for me and I would not lose space in my truck bed.

95Sierra2500 · December 15, 2006

As I said, I think the larger tank is only built for long-box trucks. I would suggest calling someplace that deals with gas tanks, or perhaps even the dealership, and ask them as you'd probably get a faster answer from them. I do know, however, that every short-box truck I've ever seen has had the small tank, and most long-box trucks have the larger tank.

Buggle_96 · December 15, 2006

I have sent an email to Fuel Safe to see if they can help me. In the meantime I still would like to know if I can replace my 26 gallon GM gas tank with a 36 gallon GM gas tank without any modifications. Does anybody know if this can be done? This is the option I would like to go with if it is possible as it will increase my fuel capacity by 10 gallons which would be enough for me and I would not lose space in my truck bed.

<{POST_SNAPBACK}>

Take a tape measure and check it out yourself. Surely there is asame generation gm truck around with a long bed on it.

asilverblazer · December 15, 2006

It won't fit it is too tall/thick to go under the passenger compartment like the original does.

CousinsDR · December 21, 2006

No, the 36 gallon tank will not fit. It will hit the back axle. However....... I have a 95 Sierra extended cab short bed with 3 fuel tanks, all mounted with factory mounts. This is what I did. The behind axle, 32 gallon tank from a Tahoe will fit where the spare is. You will need to change the 2 back frame cross members with the ones from the Tahoe. Get the mounting straps too. A stock 26 gallon tank will fit on the passenger side using the stock mounts that you get from the same truck you get the tank from. This tank will have to be modified to clear the right shock. You will have to have your exhaust moved outboard of the frame and use smaller diameter mufflers (glass packs). You can have your exhaust come out in front or back of the right tire. I opted for front. Tie the fuel supply, return and vent lines together with 2 fuel transfer valves from Pollak After Market. Run the fill lines for the 2 aux tanks up in the left real fender well. You will be able to fill all 3 tanks from the same side. By the way, I wouldn't recommend this set up for a diesel. I switch tanks when I feel the engine stumble, (out of gas), this will stop a diesel. As for the spare, I modified the spare tire mount from a Rodeo to fit on the back on my truck. I've been running this set up for 4 years with no problems. Makes towing our travel trailer a lot less stressful when we don't have to worry about gas every 150 miles, 1100 miles if not towing. The only draw back I've found with this system is that I run out of butt before I need to stop for gas.