96 CCLB 3500 7.4 only has 25 gallon tank?

[brycebba]

This truck is new to me and I was under the impression that the long bed 3500s all had the larger fuel tank, 34 gallons I think is the size but correct me if I'm wrong. It is clear that after many fill ups I have the small tank which at lowest mark I have taken it (right above the orange marks) it only took 24ish gallons to fill. Was this even an option or has the previous owner replaced the larger tank with the smaller at some point?

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[19trax95]

If you look under the hood at the sticker with the belt routing on it it should say. But then again I think it lists both tank sizes.

Im not sure if the tank is listed in the rpo codes in the glove box or not. But you can check there too.

 

[someotherguy]

Tank size is usually in the RPO codes.

The smaller tank was possible to be installed on the longbeds but I have never personally seen one done this way. Requires some different bracketry.

Most likely scenario is it has the large tank but an inaccurate fuel gauge, which is very common on the Vortec trucks...

Richard

 

[brycebba]

Ah, maybe that is true! I'm going to check the RPO codes and see what I find out

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[brycebba]

I looked up the RPO codes that reference fuel tank size and u couldn't see that any of those codes are in my list. I saw that most codes for that start with N but maybe I missed something. Here are my codes.

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[brycebba]

I checked under the hood too and didn't see anything on any stickers under there regarding fuel tank

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[someotherguy]

It may be that listing the tank size via RPO code is only typical on "special" vehicles like chassis cab trucks, because they're more likely to have variations in size - a pickup tends to have a standard size. For example my '94 3500HD had RPO NK7 which is a 31 gallon tank; that was the rear-mount tank between the frame rails of a chassis cab. There was also a skinny 22 gallon side tank many of those came with, particularly wreckers, because the equipment often prevented using a rear mount tank. (If the '92 3500 chassis cab parts truck I swiped that skinny tank from still had the SPID label I might know that RPO but I don't; and the VIN doesn't come up on Compnine)

So let's make it simple -

The 25 gallon pickup truck tank measures 46" long, 12" wide, 13.5" tall
The 34 gallon pickup truck tank measures 59" long, 14" wide, 13.5" tall

As you can see there's a significant length difference, so throw a tape measure down that bad boy and the truth will be known quickly.

Richard

 

[brycebba]

My dad took some measurements while I'm laid up. Looks like I have the 34 gallon tank based on those measurements.

I have a really bad reading from my Guage I guess. As soon as it's at 1/8 it only takes 24 gallons or so. The last 1/8 of a tank is 10 more gallons!? I am at about 230 miles once I hit that mark

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[someotherguy]

Yup, as I suspected. I've heard like...urban legends...of longbeds with the 25 gallon tank, but never seen proof. I don't doubt they exist, I just think they're rare as unicorn farts. Now what's incredibly common on the other hand, is an inaccurate 1995-up gas gauge.

Richard

 

[brycebba]

Is there anything I can do to fix the gauge to make it a bit more accurate than 10 gallons left on an eighth of a tank besides a new sending unit (if that even fixes them)

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