'fuel capacity of '73 long bed 3/4 ton 4x4

[dudevato]

I just got this truck, a GMC with a 350 with a 3 speed plus granny low. I have a filler on each side of the fleet side type 8' bed and all looks to be factory under there,

Can someone tell me the tank capacity of this setup?

Also is the electric switch switching system prone to problems? The gas gauge does not work on either tank and the whole system seems overly complicated.

On the 200 mile drive home I stopped to fill up and the right tank spilled out fuel when I took the cap off. I put it back on and filled up the left tank,

I'm already thinking of a brass valve coming up out of a hole in the floor and a 'left-right' switch to feed the gauge.

Any and all info on the subject is gratefully accepted, thank you

[willem445]

They should both be 16 gallon tanks.

I was looking into the wiring of the tanks and switches the other day as Ive been working on the wiring in my truck. Here is something I found that may prove to be useful.

http://www.plowsite.com/archive/index.php/t-11781.html

Right now i just use my driver side tank because im not sure if my switch works either.

[Zach079xxx]

Hate to say it but I hate how GM designed these. They should've put both fillers on the driver side like ford did on their dual tank trucks. Nothing more ridiculous than pulling up and filling one then switching your truck around for the other. I don't have duals I only have driver side tank, but I had problems. Turns out it was my gauge. I replaced the sending unit in the tank though just so I wouldn't have any future problems.

[Dead Parrot]

Short bed usually got 16 gallon, long bed 20. But 16 gallon on a long bed isn't uncommon.

Check the wiring and hoses to make sure a PO didn't improvise something. Sounds like your return could be plumbed to always return to the right tank so the PO didn't have to fill both sides.

[slotard]

Oddly enough I've put 20 in my long bed without filling it all the way, the friend I bought it from says he did 22, so it seems some have bigger tanks too (and I didn't think it was that low before I put 20 in).

[dudevato]

the previous owner said they were 16, I just wanted more input from you hardcore guys
thanks to willem Zach D.Parrot and slotard
is it too soon to say I love my truck?

[Firebirdjones]

Originally Posted by Zach079xxx

Hate to say it but I hate how GM designed these. They should've put both fillers on the driver side like ford did on their dual tank trucks. Nothing more ridiculous than pulling up and filling one then switching your truck around for the other. I don't have duals I only have driver side tank, but I had problems. Turns out it was my gauge. I replaced the sending unit in the tank though just so I wouldn't have any future problems.

Actually when these trucks were new, most all your gas stations had pumps with a hose that would stretch around the truck no problem. It used to be a piece of cake to fill these things up without moving the truck around.

The problem now is that the gas stations have changed and got cheap with fuel hoses, it's not the trucks fault

If you think it's fun now, try pulling a 28 foot trailer across country and filling up the truck. I had to start having my wife stand there holding the pump nozzle because by the time I maneuvered the truck around someone else had pulled in to the pump and screwed me all up, lol.

[Firebirdjones]

Originally Posted by dudevato

the previous owner said they were 16, I just wanted more input from you hardcore guys
thanks to willem Zach D.Parrot and slotard
is it too soon to say I love my truck?

If it's anything like mine, I have a 79 with factory dual tanks and they are both 20 gallon tanks. I've had the truck 20 years and never have had a single issue with the switch valve or the sending units. Works perfectly.
I loved it when traveling across country, even with the 454 I could go over 400 miles while only running each tank down to 1/4. Less fuel stops, it's nice.

If there is one thing I've complained about on my duramax is that it only has a 26 gallon tank....ugh

[Zach079xxx]

I did not know that lol makes sense. That would be impossible today

Originally Posted by Firebirdjones

Actually when these trucks were new, most all your gas stations had pumps with a hose that would stretch around the truck no problem. It used to be a piece of cake to fill these things up without moving the truck around.

The problem now is that the gas stations have changed and got cheap with fuel hoses, it's not the trucks fault

If you think it's fun now, try pulling a 28 foot trailer across country and filling up the truck. I had to start having my wife stand there holding the pump nozzle because by the time I maneuvered the truck around someone else had pulled in to the pump and screwed me all up, lol.

[Firebirdjones]

Originally Posted by Zach079xxx

I did not know that lol makes sense. That would be impossible today

That's back when we used to have "real" gas stations that doubled as service stations on just about every corner, where you could pull in and have your windshield washed, your oil checked etc... Even after that faded away we still had good pumps with retractable hoses but in the 80's that all started to fade away. Now all we have is a bunch of stupid one stop quick marts so people can shop while they buy gas and the hoses barely reach 3 feet from the pump.

Shucks it's even hard to fill up some of my cars that have the fuel filler behind the license plate in the rear center of the car. If I don't pull close enough to the pump the hose won't even reach that far, and when I'm close enough I can't open the friggin door....

Okay rant over

[jocko]

wonder if anyone has ever rigged up a reliable single fuel filler setup for the saddle tanks.... Hmmm. I'm sure a few of us have thought about it. Drives me nuts too Zach!

[wilkin250r]

If the setup is completely stock, the passenger side should be the default tank. Your 73 should be the single-wire valve, applying power to that wire (via the switch on the dash) should switch the valve and gas gauge wiring to the driver's side. Remove the power, and the valve switches back to the passenger side.

The fuel sending units in these tanks are notorious for going bad, it's not surprising at all that your gas gauge doesn't work with either tank. My gauge didn't either when I first got the truck, both sending units were bad. They're just a coil of very thin wire, and a wiper that's connected to a float will make contact at certain points along that coil of wire.

There's a ton of info on this board about diagnosing fuel gauge problems.

[Matt Man]

I have to say filling up both tanks is a pita, I was at a gas station a couple of weeks ago, I filled up one tank, turned the truck around and some woman pulled up to my spot (really?) So now I just do 2 separate transactions. Still sucks though.

[Firebirdjones]

Originally Posted by Matt Man

I have to say filling up both tanks is a pita, I was at a gas station a couple of weeks ago, I filled up one tank, turned the truck around and some woman pulled up to my spot (really?) So now I just do 2 separate transactions. Still sucks though.

Yup, that's what I was describing above, accept I was doing it trying to turn a 28 foot trailer around.

Other than that it's not really a big deal, the only time I'm filling both tanks is on a long road trip and that's not very often at all. My wife drives it daily to work and she can go all week on one tank. So what I do to keep the valve working and the tanks circulating is that I fill up the other tank every other week.

It's not like I'm taking this truck across country every weekend, it might go on a long road trip once a year. So I've never felt the need to combine the tanks. The system has worked flawless on mine since the truck was new so I leave it alone.

One benefit I find that I like about it is that when you pull into these busy gas stations, especially when they are one direction as so many are nowadays, you aren't a prisoner of trying to pull in to one side and sometimes forced to wait. With these dual tank trucks and fillers on either side, I can pull up to the pump on any side I want to and fill it. I do like that part of it.

[Chevy_mud_truck]

Originally Posted by jocko

wonder if anyone has ever rigged up a reliable single fuel filler setup for the saddle tanks.... Hmmm. I'm sure a few of us have thought about it. Drives me nuts too Zach!

There a member on here that has a set up on a dulley that he can fill both tanks from ether side but I can't remember his name I'll try to find it or a picture of his setup

[dudevato]

Wilkin, thanks for your reply about the gas tanks in these trucks, I'll make a note of it and be ready when I tackle this problem.

It is Too Cool to have an old, good running truck I can jump in with my boots on and everything works. thanks for the help. Gary in Red Bluff, CA.

[jocko]

Originally Posted by Chevy_mud_truck

There a member on here that has a set up on a dulley that he can fill both tanks from ether side but I can't remember his name I'll try to find it or a picture of his setup

well let us all know when you remember, that would be a worthwhile mod. I did find some info here http://67-72chevytrucks.com/vboard/s...ad.php?t=28687

[Chevy_mud_truck]

Here a picture I don't know how to put up a link off of my phone