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Question about 40 Gallon Suburban Tank and its skidplate

dbreid

dbreid

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All,
I have a 1989 Suburban with the smaller gas tank. It is still big, of course, but as I take a lot of road trips, I have considered upgrading to the 40Gallon tank.

My questions are:

1.) Is there a special Skidplate for the 40 Gallon tank? I have the skidplate under my tank, and it is excellent.

2.) How much lower does the 40 Gallon hang?

3.) Are there different fuel sending units for the 40Gallon?

I did a search, but most of the threads focus on 40Gallons into the K5, which means moving crossmembers...

Thanks in advance!

-Dan
 
An update for myself...

In looking at LMC again after posting this, I noticed I had missed the Dimensions:

25 Gallon = 28 3/4" x 28 1/8" x 10 3/4"
31 Gallon = 28 3/4" x 28 1/8" x 12 3/4"
40 Gallon = 35" x 28 3/4" x 13 1/8"

So it looks like the 31 Gallon just hangs down another 2 inches. And the 40 Gallon hangs down a little less than 3 inches over the 25.

Looks like the 40 is a little "deeper" (front to back?) as well?

Looks like the 31 Gallon and the 25 Gallon might be able to use the same skid plate with some spacers?

-Dan
 
I don't know about the 40 gallon. But as far as I know...the 25 and 31 use the same skid plate. There is a gap between the two when used with the 25 gallon tank.
 
I am going to bump this in case anyone found the answer. I haven't done this yet, but I am thinking about it again.
 
Sending unit would have to be different since depth changed.

I remember running into a part number "discrepancy" between the K5 and Suburban sending units, but now I suspect that what I was seeing referenced was a 40 gallon sender vs. the 31 gallon.

I might be able to look the 40 gallon sender GM part number up if you like, but I expect many aftermarket places (like napaonline.com, rockauto.com, etc) would also show the interchange. acdelco.com's part search is somewhat less easy than others, but it will give you the AC part number as well as the GM one, which often helps with finding interchanges.

FWIW, I'd stick to NOS GM stuff if you get the option, if you could find a sender from 1989 new in the box, I'd trust it more than a 2014 product, Delco, Delphi, or other. It's pretty much all coming from China now, and cost is the driving factor at this point, not longevity.
 
Agreed on different sending units. But what about the skid plate? All the same?
 
Skid plate has to be as well, tank is longer. There is little/no room left between the 31 gallon skid and the bottom of the 31 gallon tank anyway, so depth-wise it wouldn't work either.
 
I definitely do road trips, but I also wheel the truck some (mild compared to my other truck of course). Plus, I like the protection from debris (and water and slush and other junk) coming UP. Not just me landing the truck on something.
 
Yeah, I'm nowhere near a hard core wheeler, but I've driven over a couple of tree limbs and what not that "kick up" and strike the undercarriage, those tanks are pretty weak, I figure it can't hurt to have it.

Honestly though, other than dragging on some obstacles, the trailer hitch does more work to protect the tank than the skid.
 
You might also want to spot weld some side plating onto your skid plate if you're running lifted. Had my forty gallon get some scary looking dings courtesy of gravel kicked up by a wrecker flying up an unpaved road.
 
dyeager535 said:
I might be able to look the 40 gallon sender GM part number up if you like, but I expect many aftermarket places (like napaonline.com, rockauto.com, etc) would also show the interchange. acdelco.com's part search is somewhat less easy than others, but it will give you the AC part number as well as the GM one, which often helps with finding interchanges.

FWIW, I'd stick to NOS GM stuff if you get the option, if you could find a sender from 1989 new in the box, I'd trust it more than a 2014 product, Delco, Delphi, or other. It's pretty much all coming from China now, and cost is the driving factor at this point, not longevity.
Click to expand...


I have an 85 with the 40g. Was wondering where I would find a new in the box type dealio. "1/2" tank is empty and when I throw all 40 gallons into her, she shows about a 1/4 inch past full!
 
1985 K10 Warhawk said:
I have an 85 with the 40g. Was wondering where I would find a new in the box type dealio. "1/2" tank is empty and when I throw all 40 gallons into her, she shows about a 1/4 inch past full!
Click to expand...

That sounds more like your sending unit or the wiring has crapped the bed.
 
Why not just find a Burb with a forty and swap everything over. Its bolt in, they came with them, a lot, should be easy to find. Then you have nothing to figure out just bolt it in and go.
 
His sending unit is probably for one of the smaller gas tanks--it's probably working OK,it just is not accurate..the rod the float mounts on could be cut and extended to make it the right length to read correctly..

I remember after putting a new gas tank in my '82 Cabalaro ,the gas gauge was no longer accurate--it still had 1/4 of a tank when it read empty--after I got the thing bolted all in I found a sheet of paper in the box the tank came in,saying you can either modify the sending unit float height,or buy the "correct" sending unit...I didn't want to take it all apart again,so I lived with it--better it having more gas than it says it did,than running out and still showing 1/4 of a tank is left...:doah:
 
He has an '89, and if it's still fuel injected, even the smaller tank sending unit won't be very friendly if it's a shorter tank model, not that the gauge will read wrong, but the electric fuel pump won't reach the bottom of the tank, he'll never be able to use the full tank of fuel, he'll run out a bit sooner even with gas still in there.

The sending/pump unit in the tanks go all the way to the bottom with the pick-up sock. That's what always gets me when people say "I ran the tank too low and picked up garbage and dirt from the bottom" IT ALWAYS picks up from the bottom.
 
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