1999 K2500 Fuel Tank Swap

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CBenZ71

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Okay, so I have a '99 K2500, 4 door that has the 25ish gallon fuel tank. I have been looking at trying to put a 42 gallon Suburban tank where the spare tire sits(I dont need the spare because I have 35s anyway) and removing the stock fuel tank. I have the 7.4 so I only get maybe 10 MPG city and 8 when towing. Has anyone ever done this? Is it possible?? Any knowledge or advice is greatly appreciated.
 

BlastingBat998

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I personally own a 7.4 suburban and have been around other 7.4 trucks, there are two metal bands that hold the tank up secured by (correct me if i'm wrong) i believe two large 15mm bolts, so far in my opinion your biggest obstacle would be how do you get your gas cap tubing all the way back there? and you would possibly need to make custom mounts in order to hold it up properly. and extend your current fuel lines and wiring for the fuel pump. Uses the same fuel pump. I believe it is possible with a little wire work, mounts, and rubber tubing. Good luck!
 

RDF1

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42 gallon take is quite large. Might want to do a lot of measuring before you start. I made a 19 gallon fuel cell for behind the axle on my 91 and ive only got about 2 inches from the diff cover and 1/2" from the rear bumper. But it is tucked up to the bed and doesnt hang below the bumper. Over double the gallons is gonna be quite fun to fit back there.
 

CBenZ71

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42 gallon take is quite large. Might want to do a lot of measuring before you start. I made a 19 gallon fuel cell for behind the axle on my 91 and ive only got about 2 inches from the diff cover and 1/2" from the rear bumper. But it is tucked up to the bed and doesnt hang below the bumper. Over double the gallons is gonna be quite fun to fit back there.

Good point! Thanks for the feedback. I was hoping that the frames would be the same making it easy, but having a short bed I'm betting the Burbs frame is larger allowing the tank to fit. The fuel cell is a good idea though, I may try that instead. I just don't want to have to stop every 200 miles to refill while towing. Lol
 

RDF1

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Well not just that. The Sub is a longer wheel base so you have alot more length under there to fit a 10' long fuel tank haha.
Spare tire area is very limited.

If you want to look into it, a early 90s F150 has a 18 or 19 gallon rear fuel tank and they can be had for under $100. They fit where the spare was pretty simple.
I had one on my tahoe and ended up removing it and building a 30 gallon cell. Its a tight fit tho. That F150 tank had a little room to spare.

Im with you tho, i did that so when towing i didnt have to stop every 2 hours....

Also, i used a Walbro 255 pump that fed the fuel to the filler neck close to the main tank. I used a Mosfet timer box and figured out the GPM and set the timer to only run enough to empty the AUX tank into the main tank and not let the pump run dry too long.
 

andy396

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Would a 34 gal tank that replaces the existing 25gal tank be an option?
 

CBenZ71

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Would a 34 gal tank that replaces the existing 25gal tank be an option?
I thought about that but from what I read, it would have to be a long bed to get that to fit, not enough room on the short bed.
 

CBenZ71

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Well not just that. The Sub is a longer wheel base so you have alot more length under there to fit a 10' long fuel tank haha.
Spare tire area is very limited.

If you want to look into it, a early 90s F150 has a 18 or 19 gallon rear fuel tank and they can be had for under $100. They fit where the spare was pretty simple.
I had one on my tahoe and ended up removing it and building a 30 gallon cell. Its a tight fit tho. That F150 tank had a little room to spare.

Im with you tho, i did that so when towing i didnt have to stop every 2 hours....

Also, i used a Walbro 255 pump that fed the fuel to the filler neck close to the main tank. I used a Mosfet timer box and figured out the GPM and set the timer to only run enough to empty the AUX tank into the main tank and not let the pump run dry too long.
Now that is a cool idea! I'll probably try that instead, I'm think the burb tank just is too big, similar to the 34 gallon. If not the Ford tank I'll probably just try the Cell. Thank you!
 

RDF1

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I know they are spendy but Titan fuel tanks has a diesel version that replaces the spare tire and it holds 30 gallons. But they are north of $1500...
 
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