Physical size of fuel tanks 16 vs. 20 gallon

[bshupe]

I have had this M1031 for a month or so and have filled the fuel tank three times I think. The last time it was so low on fuel I was worried about making it to the fuel station and when I filled up I couldnt get more than 15 gallons in. I thought the truck had a 20 gallon tank but maybe it doesnt or it was swapped out at some time in the past. I suppose the sending unit could be off by 5 gallons as well but that doesnt seem likely.

Does anyone have a confirmed 20 gallon tank that they could provide rough dimensions of for comparison?

Thanks!

 

[doghead]

The TM says 20 gal.

 

[Matt65]

The last time it was so low on fuel I was worried about making it to the fuel station and when I filled up I couldnt get more than 15 gallons in.

I am rarely able to get more than 15 in mine as well. It seems that when the gauge hits E, there are several gallons actually remaining.

 

[panama]

My M1009 is the same. Fuel gauge gets to "E" and I can get 16-17 gallons in it. Probably safer like that, although I always wished I could "adjust" the gauge to the left a bit.

 

[rickf]

When you think about it 5 gallons spread out over the bottom of the whole tank is a fairly thin layer.

Rick

 

[doghead]

An M1009 has a 27 gal tank.

I go about 120 miles(m100 between fill-ups, that's every 2 hours on a highway trip. I have squeezed 16 gallons in, and I have not run out.

The GA rally trip take 8 or 9 fuel stops, each way!

 

[islandguydon]

My tank says empty and I still have approx 5 gallons left in her. I felt the Gage was messed up as the norm.

 

[bshupe]

Hmm. So maybe a design flaw, or built-in safety.

I looked at the TM and saw it said 20, that was where I was getting my original research info on adding a second tank etc. When I ended up with an M1031 it actually has a sticker on the dash that says its a 20 gal tank. It would make sense if you were using it to run a generator in the field. The fill-ups made me question it though and with the amount of times a fuel tank gets damaged by bases storing these trucks it seems likely that it could have been changed out.

I think I can get good enough measurements on the one that in there to estimate the volume and capacity.

Im thankful for the input here though. I dont feel so crazy now. I am a little let down though since all my economy calculations were going to get a 30% boost if it was a 16 gallon tank. Im getting 17-18 now even pulling a light trailer but 22 would have been even better. lol

 

[True Knight]

When you think about it 5 gallons spread out over the bottom of the whole tank is a fairly thin layer.

Rick

It's very true. Not once have I seen a stock fuel tank on any vehicle be truly empty when the fuel system can't suck up any more fuel. There is always a few extra gallons spread along the tank bottom. And it really is a thin layer too.

 

[4x4 Forever]

I have seen LWB GMs of those years built and shipped with a 16 gal tank, I had one! SWB is 16 gal. and LWB is 20gal.. You might want to look up a replacement tank from JC Whitney or other supplier and measure the length of the tank. If I remember correctly, the length is the only difference, if I'm wrong on this, I should be shortly corrected.

Having a 20 gal tank and filling it up every 15 gals or so makes sense, bleeding a diesel is NOT fun!

 

[4x4 Forever]

I have seen LWB GMs of those years built and shipped with a 16 gal tank, I had one! SWB is 16 gal. and LWB is 20gal.. You might want to look up a replacement tank from JC Whitney or other supplier and measure the length of the tank. If I remember correctly, the length is the only difference, if I'm wrong on this, I should be shortly corrected.

Having a 20 gal tank and filling it up every 15 gals or so makes sense, bleeding a diesel is NOT fun!

 

[Darwin T]

there are 2 tank sizes for those year models, 16 gallon and 20 gallon. my M1028a2/3 with maintance bed has the 16 gallon. i am looking into adding another tank on the passenger side. while looking i found the 20 gallon tanks. if i add an extra 20 gallon tank on the passenger side i am going to change the drivers side tank to a 20 gallon also.

 

[11Echo]

Over the years I have bought many GM pickups and always ordered the auxiliarly tank for the other side. I have often run a tank dry on extened trips before switching to the other side and have had no problem getting 20 gallons in it showing that whatever the physical size of the tank, I could get it's listed capacity out of it.
I never had a M1031 or worked under one so don't know what tank they run. My M1008 does have the 20 gallon tank.

I run this Chevy dry and just switch to the other side. The empty tank always takes 19.8-20.2 gallons at fill up.

 

[Recovry4x4]

56" OAL. This includes the lip where the top and bottom are joined together. This is a 20 gallon tank. All tanks are similar in design, just vary in length. Also, the neck attached to diesel tanks is slightly larger.

Found this site. http://www.mtscompany.com/chevy-gmc.htm It confirms my measurements. Says 54" and I'm going to assume that is without the lip I mentioned. Also indicates that the 16 gallon tank is 41".

HTH

 

[Keith_J]

I filled up the 1031 the other day and it took 18.6 gallons. The gauge needle was just a tick above empty. I guess the tank sock is in good shape, it it had any significant cracks/breaks, there is no way it would have continued to run.

 

[86m1028]

there are 2 tank sizes for those year models, 16 gallon and 20 gallon. my M1028a2/3 with maintance bed has the 16 gallon. i am looking into adding another tank on the passenger side. while looking i found the 20 gallon tanks. if i add an extra 20 gallon tank on the passenger side i am going to change the drivers side tank to a 20 gallon also.

All the ones I have seen are 20's.



Edit Darwin T I always like seeing pics of your truck

 

[86m1028]

I have had this M1031 for a month or so and have filled the fuel tank three times I think. The last time it was so low on fuel I was worried about making it to the fuel station and when I filled up I couldnt get more than 15 gallons in. I thought the truck had a 20 gallon tank but maybe it doesnt or it was swapped out at some time in the past. I suppose the sending unit could be off by 5 gallons as well but that doesnt seem likely.

Does anyone have a confirmed 20 gallon tank that they could provide rough dimensions of for comparison?

Thanks!

I can tell by the pics in your build thread that you have a 20 gal tank.

 

[Barrman]

At least the truck tanks have a civilian tank match up that can be measured. The M1009 doesn't. The TM says 27 or 28 gallons. Yet, the civilian trucks had either 25 or 31 gallon tanks. LMC says the only difference is the depth. 10-3/4" for the 25 gallon or 12-3/4" for the 31 gallon. My M1009's have tanks that measure 10-3/4" the best I can tell from underneath.

Not trying to dirty up this thread, but as stated above, running a tank dry is not fun. I figured the 1009 people out there shouldn't push their range much more than what they can do on 25 gallons. I also think the suggestion above about the larger filler neck and tube are where the extra 2 gallons come from. How much is usable? I don't know. Mine has never taken more than 23.5 on fill up.

 

[combatmech]

Since the installation of a 31 gal tank in my M1009, I have been able to go about 400 miles between fill ups. When I first installed the tank, I would let get to just below 1/4 tank before fill up. At that point it would take about 19-20 gallons.
Since then, I let it go to E. When I do fill it up, I get about 23-24 gallons back in the tank. I dont want to push my luck even though I know there is still going to be about 5-7 gallons left on E.

 

[wallew]

I've gotten 19+ gallons in my M1028A2 and 26+ gallons in my M1009 (both of the ones I've owned). But I run them down low when I've been on road trips. I always carry 5 gallon NATO fuel tanks. And bleeding MINE are a breeze with the electric fuel pumps installed.

Just turn on the key, open the bleed valve, wait a few seconds until fuel spurts out and you are done. There ARE good reasons to add that electric fuel pump. It's relative cheap maintenance addition, plus it gives a solid 5 psi min fuel pressure.