Fuel tank help

[MrN2OBelvedere]

Hey guys, I have a 1985 gw. I'm pretty sure the fuel tank is in need of replacement. Looking around for replacement for this year rang is proving to be difficult. Does anyone know if the tanks from the late 70s models can be adapted? Or does someone know where I can get a replacement for the 85?

[babywag]

It is very unusual for a 80-91 wag tank to need replacement.
Having cut a few up for disposal they are THICK and pretty tough.
Verify it is not just a hose or grommet leaking.
There are 2 grommets on top for vent/vapor lines with small valves they can leak.
The o-ring on the sending unit can also leak.

[MrN2OBelvedere]

Thanks for the reply.

I am having problems with eating up fuel pumps and clogging filters. Not really sure if this is rusting or something else like a deteriorating fuel line(s). I suppose what I'll do is pull the tank first and have a look around it to assess the condition of it.

[babywag]

tanks are poly(plastic)...they don't rust.
lines on every late model I've see have been stainless unusual to rust.
small fuel hoses @ tank pickup/sending unit are probably original & rotten @ least all ones I've seen have been.
there is also a "sock" filter on pickup tube inside tank they deteriorate badly after 30+yrs as well.

drop tank, wash it out with hot soapy water, let it dry.
replace the small sections of 5/16" & 1/4" hose.
blow out hard lines with compressed air.
check "sock" in tank

[MrN2OBelvedere]

Thanks for this, I appreciate it. I think the late model tanks are metal?

Anyhow that is my next course of action. I'm going to pull the tank and try to clean it out. I don't think I will use water though, probably will use something like acetone or laquer thinner. Depends on what I find tank material wise. Acetone can destroy some plastics in short order.

I was thining that there could be a sock filter of some kind.

Here's the odd thing. At startup when cold, the mechanical pump will make adequate pressure (I have a gage showing around 5 to 6 psi). Once its warm it drops a lot, down to the 2-3 psi range. Anyhow we'll see what I find once I drop the tank. I'll definitely take the opportunity to clean out all the lines and replace the hoses.

[SJTD]

My '84 is plastic. Never heard that they went back to metal.

If you find it has goo in it take a sample with a stick and see what works to dissolve it before wasting time and material on the whole tank. Add some nuts and bolts or gravel or something with the cleaner to help get the gunk out.

They have a sleeve in the filler neck that sticks into the tank past the wall making it hard to get the last bit of liquid out. I tool it out an left it out to maybe gain a little capacity.

[MrN2OBelvedere]

That sleeve may be to maintain an air volume to vent the tank and allow for volume expansion of the fuel. I had a muscle car once that had issues with the vent system on the tank, and with a full tank of gas if you left the car in the sun the Fuel would start spilling out of the fill cap. I lived in an apartment at yuw time and realized I was smelling gasoline from the apartment. Looked out the window and there was a stream of fuel coming out of my car and running down the parking lot!

Anyhow I'm driving the jeep around now trying to burn some of the fuel out, of course I have a full tank of gas

[miracleed]

on the rare occasion that there's a problem with the forums being accessible i tool around the other links on the home page. if found a lot of really good write ups that are easier to find (for me at least) than trying to remember a build thread i might have read eight months ago by that guy with the chero or waggy or was it a jtruck... which is about as good as my memory gets these days.

there's a section called tech library that's pretty amazing:

here's fuel stuff:

http://www.ifsja.org/tech/fuel/index.html

and specifically fuel tank stuff:

http://www.ifsja.org/tech/fuel/gastank.html

http://www.ifsja.org/tech/fuel/skidplate.html

I don't see any fuel tanks listed for the GWs on the parts sites I frequent so I tend to believe the guys above in saying that they rarely rot out... those sites are more than happy to fulfill a need and take a few hundred bucks in return. All the ones I saw listed were for older trucks. One of the reasons I linked the stuff above was that they urge a lot of caution, because of boom, I was surprised to re-read the gas tank removal article and not see the step I thought I remembered there (see previous note about memory). One of the first things that people I know of recommend is once you've got the tank out and drained was to fill it all the way with water and force out any gas vapors that might be hiding in there. Good luck.

[MrN2OBelvedere]

Thanks I appreciate the links. I'm not too worried about the safety concerns. I've dropped a handful of gastanks in my day and I do observe extra caution for sure. I'm dreading pulling the tank though. Its not going to be a fun task I am sure.

[miracleed]

no doubt; on your back, dirty, smelly, gasoline and grease dripping into scraped knuckles... good news is that it will probably only take all day and who knows if you'll find what's wrong. paradise.

[babywag]

If it was me...
I'd remove the access hole plate under the back seat.
Pull the sending unit.
Replace the pickup "sock" on sender.
Blow out the hard lines with compressed air.
Replace the two short sections of fuel hose and button it back up.

While sender is out you can inspect the tank to see if there is gunk in bottom.
You can also use larger hole to siphon most of fuel out if still dropping tank.
A spoon with bent handle secured to a dowel or rod can be used to scrape the bottom of tank to check for gunk.

Dropping tank is pretty easy on these as the poly tank is secured to big skid plate/coffin setup bolted to frame & body.
If fasteners are crusty spray them with something like PB blaster a few days before dropping it.

[MrN2OBelvedere]

Good call. I may just go this route.

[tgreese]

If it was me...
I'd remove the access hole plate under the back seat.
Pull the sending unit.
Replace the pickup "sock" on sender.
Blow out the hard lines with compressed air.
Replace the two short sections of fuel hose and button it back up.

While sender is out you can inspect the tank to see if there is gunk in bottom.
You can also use larger hole to siphon most of fuel out if still dropping tank.
A spoon with bent handle secured to a dowel or rod can be used to scrape the bottom of tank to check for gunk.

Dropping tank is pretty easy on these as the poly tank is secured to big skid plate/coffin setup bolted to frame & body.
If fasteners are crusty spray them with something like PB blaster a few days before dropping it.

Good advice from Tony. Those short sections of hose on top of the tank are a common source of trouble, either leaking or fallng apart. Suggest you use some high-quality hose in this area, either EFI-rated hose (a bit pricey) or the Gates hose available in bulk from RockAuto. Also an opportunity to get a nice long length of hose to use as a siphon hose, to carry with you.

[MrN2OBelvedere]

Hey guys out of curiosity what is the stock fuel pump pressure when warmed up?

[tgreese]

Hey guys out of curiosity what is the stock fuel pump pressure when warmed up?

About 5 psi. There is a spec in the TSM.