85 GMC fuel tank

[oldwhity]

I noticed a puddle under the truck today and saw that it was leaking fuel. It appears to be right above one of the supports/mounts. I figure there was dirt boring a hole in the bottom of the tank. The local junkyard has tanks for $25 for our trucks.

What years are interchangeable? If I have a 16gal tank, will a 20gal fit? I believe mine has a 3 outlet sending unit, will it fit in a tank that currently has a 1 or a 2 outlet sending unit? Thanks in advance.

[Captkaos]

You only need the tank not the sender.  Just use yours.
get a tank that is the same as what you have.  If yours is a Short Wheelbase, you ONLY can use 16g tanks.

[oldwhity]

Thanks Capt. It didn't leak at all today . Is there an overflow? Yesterday it really acted like there was a pinhole leak. I fill up every day even if it's just to top it off and I usually round it up to the nearest dollar. Sometimes I know it gets pretty full but has never leaked before.

Also, are the tanks symmetrical? I was thinking about converting to dual tanks and was wondering if I had to find a donor with a passenger side tank. Thanks again!

[frogman68]

Thanks Capt. It didn't leak at all today . Is there an overflow? Yesterday it really acted like there was a pinhole leak. I fill up every day even if it's just to top it off and I usually round it up to the nearest dollar. Sometimes I know it gets pretty full but has never leaked before.

Also, are the tanks symmetrical? I was thinking about converting to dual tanks and was wondering if I had to find a donor with a passenger side tank. Thanks again!

Tanks are the same the sending units are different from each side

[fitz]

Oldwhity, Have you thought about going to a Blazer (34 Gal) tank instead of converting it to 2 16 gallon tanks? I would imagine if you got a used tank it would cost about the same.

[oldwhity]

Thanks Frog. I went to the junkyard today to see if I could find a tank for their advertised price of $25 and some change. There were about a dozen or so but all were punctured . I don't get it. Why advertise it!

Thanks Fitz. Mine is a 20gal currently but I wouldn't be opposed to putting 1 34gal instead of 2 20gal tanks. Is that what you have? Would I still be able to use my sender and just reroute and extend wires and hoses? Thanks again fellas.

I did make out with a factory grille in great shape for $20. I was tickled about that.

[oldwhity]

Dag nabit!!! I was waiting to pull out of a gas station today(second in line) and the fella in front of me pulls out a little(I stayed put) and decides he's sticking out a little too far. So he throws it in reverse and starts backing up! As soon as I see the reverse lights I put it in reverse and check my mirrors to back up. Well, before I could let off the brake it happens. My freshly painted , less then 24hrs old, factory, took forever to find, junkyard gem was cracked.

[eventhorizon66]

You mean the grille?  Have his insurance pay you for a new repro or NOS grille.

[fitz]

Oldwhitey, sorry to hear about the grill.
Yes, my truck has the blazer tank in it. captkaos wrote a great tech. article on the install.   

http://www.captkaoscustoms.com/blazertank.html

As far as your sending unit I don't think it will work in a blazer tank because the blazer tank is deeper (I think). Your best bet would be to find a tank out of an 86 or older truck, The 87+ would have the fuel pump for the TBI in the tank.
Hopefully you can find a truck that already had the tank replaced in it. I've parted out allot of these trucks and many of them had replacement tanks in them.
If you do decide to go this route search around on this site. Some of the guys have come up with some creative solutions for the filler neck comming through the bed floor.

[oldwhity]

You mean the grille?  Have his insurance pay you for a new repro or NOS grille.

Yeah, my "new to me" grille. Knowing that I only paid $20 for it, it's not in my nature to try and get more out of the situation. I settled for a $20 bill. It was just frustrating because I just got it yesterday. I think i'll take it out and try to brace it from behind and repair as good as I can.

Fitz, I think i'll definitely keep that option in mind. I did notice that the Blazer tanks cost more new. We'll see what pops up in terms of a donor. Thanks

[oldwhity]

Well that was fun! Saturday I pulled the tank and found 3 small rust holes. Of course they were covered by the forward most strap. I only patched the holes as a temporary fix and still plan to replace the tank later.

Btw: Is there an easier way to remove and reinstall the 3 fuel lines from the sender? I'm about 150lbs wet and still had a hard time with the tank partially dropped and as far away from the frame as possible. Thanks

[frogman68]

Well that was fun! Saturday I pulled the tank and found 3 small rust holes. Of course they were covered by the forward most strap. I only patched the holes as a temporary fix and still plan to replace the tank later.

Btw: Is there an easier way to remove and reinstall the 3 fuel lines from the sender? I'm about 150lbs wet and still had a hard time with the tank partially dropped and as far away from the frame as possible. Thanks

We are about the same size and with the bed on I could not see how to do it.
What I ended up doing was cutting the three tubes further back towards the engine and running rubber hose to the sending unit (I attached them at the tank feed em over the frame then lifted and bolted tank in) then attached the rubber hoses to the tubes going to the engine.

[oldwhity]

Thanks Frog, I may do that next time. I'm really surprised the patch is holding up. I'm crossing my fingers for it to hold until we make it over this speedbump in life were going through. Thanks again.

[topnotchchevy]

Hey oldwhity i had the same problem with my gas tank in my 1979 c-10 but wat i did was i took the tank off and completly cleaned it up left it like brand new and den wat i did was use JB welder nd put it over da small hole it had wer it was leakin i put it on twice and it hasnt leaked dat did real good so if u ever have problems again u can consider doin dat its cheaper den jst gettin another one

[VileZambonie]

den dat dounds wike da dood idear