olenmarmcr
Registered Member
Im trying to buy a new sending unit but dont know if my tank is 25 gallon or 31. How can i tell.
CK5
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fuel tank confusion.
- Thread starter olenmarmcr
- Start date
Measure it, do a little math...
4xcrazy
3/4 ton status
You don't remember running the tank almost empty at some point in time, then maybe filling it up? or passing the 25 gallon mark at some point during a fill up?
I know that's alittle rough with current times to spend that much in fuel, but it's how i know i have a 40 gallon tank in mine..
road trips in the past
I know that's alittle rough with current times to spend that much in fuel, but it's how i know i have a 40 gallon tank in mine..
road trips in the past
that's not going to help
give us a picture of your tank from the side, normally can tell that way
or like was mentioned, measure your volume, top x side x length and you can have your gallon size that way
or drive it tell it runs out, push it, fill it, and then you will know for sure x2
31. Gas Tank Dimensions 28 3/4" X 28 1/8" X 12 3/4"
31g tank is 2in taller and has a angle cut in part of it.
25. Gas Tank Dimensions 28 3/4" X 28 1/8" X 10 3/4"
25 g is flat on bottom ....
31g tank is 2in taller and has a angle cut in part of it.
25. Gas Tank Dimensions 28 3/4" X 28 1/8" X 10 3/4"
25 g is flat on bottom ....
NorCal Chris FTW!31. Gas Tank Dimensions 28 3/4" X 28 1/8" X 12 3/4"
31g tank is 2in taller and has a angle cut in part of it.
25. Gas Tank Dimensions 28 3/4" X 28 1/8" X 10 3/4"
25 g is flat on bottom ....
nice post NorCal
rampage
3/4 ton status
Actually, I did this last year and that doesn't give you the correct tank size. Here's what I found (yeah I got bored one night
) :CAUTION MATH AHEAD !!
So I went to my garage and measured my 31 gallon tank that is removed from my Blazerhttp://blazerforum.com/forum/# - I got 27 x 26 5/8 x 11 3/4. Hmmm, seems like the LMC is actually posting the shipping dimensions because when I measured the lip around the perimeter it was 3/4".
So I did some calculations:
Volume of tank= 27x26.625x11.75 = 8446.78 cubic inches
But we need to remove some volume because the tank isn't exactly rectangular (angled portion on the bottom and the rounded corners)
Let's start with the prism shape we need to remove:
It's 1 5/8 high by 6 7/16 long (which means the hypotenuse is 6.639 - which we'll need later on).
Volume of prism= 1/2 x 1 5/8 x 6 7/16 x 26 5/8
or = .5 x 1.625 x 6.4375 x 26.625 = 139.26 cubic inches
Now we need to deal with the rounded edges:
The radius of the edges is 1.5 inches. If we take a snapshot of the profile of one of these edges it's a quarter circle. But the part we need to subtract isn't a quarter circle - it's the outside part of the quarter circle. Think of a quarter circle with radius 1.5 and then draw a square around that whose sides measure 1.5. We want to remove everything outside the quarter circle.
Area outside of quarter circle = (area of square) - (area of quarter circle)
or = (1.5 x 1.5) - 1/4(3.14 x 1.5.x 1.5)
= (2.25) - (1.77)
= 0.48 square inches
So for every linear inch of rounded edge around the tank we'll subtract 0.48 cubic inch
Adding up all the edges (this is where the hypotenuse comes into play) we get (if someone really wants me to explain where all these numbers came from I will but for simplicity sake I didn't include it):
(4 x 26.625) + (2 x 27) + (2 x 11.75 ) + (2 x 10.125) + (2 x 20.5625) + (2 x 6.639)
= 106.5 + 54 + 23.5 + 20.25 + 41.125 + 13.278
= 258.653 linear inches
So the volume we need to subtract for all the rounded edges is:
258.653 x 0.48 = 124.15344 cubic inches
The actual volume of the tank = 8446.78 - prism - edges
= 8446.78 - 139.26 - 124.15
= 8183.37 cubic inches
Now we know that 1 gallon = 231 cubic inches. Or we could just plug these numbers into my favorite online conversion site and find that the tank roughly holds 35.43 gallons. The level at which it actually holds 31 gallons is 1.42 inches below the top of the tank. Again, I think this is to help prevent fuel from splashing out if the rubber fill tube is faulty at that point.
So what I guess I'm trying to say is that you have a 31 gallon tank.
31. Gas Tank Dimensions 28 3/4" X 28 1/8" X 12 3/4"
31g tank is 2in taller and has a angle cut in part of it.
25. Gas Tank Dimensions 28 3/4" X 28 1/8" X 10 3/4"
25 g is flat on bottom ....
What is the purpose for the angle cut?
rampage
3/4 ton status
Probably departure angle
Easy way is if you have a skid plate. 31 gallon tanks nearly touch the skid plate, 25 gallon tanks have a very noticeable gap....basically the 2" Norcal mentions.
Another option is to just measure the "length" of your current sending unit, assuming you have one and the tank is out of the truck. The 2" would be measurable that way as well.
You didn't ask nor say, why are you replacing the sending unit? Maybe can save you some hassle if it's a problem that can be fixed another way.
Another option is to just measure the "length" of your current sending unit, assuming you have one and the tank is out of the truck. The 2" would be measurable that way as well.
You didn't ask nor say, why are you replacing the sending unit? Maybe can save you some hassle if it's a problem that can be fixed another way.
