I'm redoing my fuel system and had a few questions-

1. The gasket for the sending unit, is it also the same seal that goes under the locking ring? I have a behind the axle tank:
Sending Unit Seal, All Tanks
Sending Unit Lock Ring and Seal, All Tanks

Not to seem too knuckle headed but they look the same, I just want to make sure I order everything the first time and don't need two of them. Any special tool to get that ring off?

2. I'm going to POR15 the outside of the tank, but what is the advantage of applying a rubberized undercoating? I might just topcoat the POR15 silver or something like that.

3. When is it time to apply inside the tank sealer? If it looks not to rusty, I'd think no reason to do so?

Thanks for the input. -Mike

 

The gasket is the same. There's only one gasket per sending unit. I use a screwdriver to remove and install the lock ring.
The only tank that uses a different gasket is the in-cab tank.
As for POR15, that's more personal choice same for the undercoating.
Personally I'm not a big fan of tank sealer unless it's necessary. I've seen several "bad" coating jobs. If the tank is bad enough to require sealer, just replace it. They're cheap enough.

 

x2 on just one gasket and x2 on the screwdriver or use a punch. You might have a tab that is bent a bit to lock it on. Un bend and tap the lock ring loose.

Just paint it or seal it with what ever you like, but also replace the anti chaff material on the bottom support straps. Old 2" wide ratchet strap glued on there, works great.

I would only seal the inside of a new tank, use 2 inline filters (one before the pump and one after) and it its bad enough to have to use the inner seal kit, just get a new tank or go plastic and never worry about rust again.

 

So I got my shipment of LMC parts in today and found out the fuel tank breather valve does not exactly match the one that was on my truck. The one from LMC is shorter and squat and the ball inside freely rattles around. The older one was long and skinny (but still a single port). I think the new valve was for a 1978/79, not a 1973. Does it matter? The rubber gasket is not interchangeable between the two due to the diameters but does still fit the tank hole. Should I even worry about this?

 

No.
The parts catalog shows the 73-74 trucks used a different part number than the 75-up.
As long as the valve fits in the tank I would say it's okay to use. All this is is a check valve. It's also very possible that the valve that you have is a superseding part for the early valve.
Also, the valve rattling is okay.

 

Bump

1. I'm looking for input on installing new fuel lines and brake lines. For the lines forward of where the brake lines have a metal coupler and the gas lines have a rubber coupler- how much of the engine bay do you need to disassemble to install new lines? I can't imagine how the fuel line snakes out past the steering hydraulic cylinder. Also, the brake lines are pretty twisted through frame holes. Can the stock replacement lines really be put in without removing the engine and its friends?

2. On the on in-tank fuel filter- what color is it supposed to be? Mine was brown when I pulled the sending unit. No gunk on it, just an ugly color. I couldn't figure how it disassembles without breaking anything so I left it on.

Thanks for the input!

 

Not sure on 4WD but on the 2WD you'll need to unbolt the steering box, the lines are routed behind it.
The stock filter is an off white color. I've seen them from white to off white.
Here's a NOS filter unit and some pictures of the fuel/brake lines.

 

x2 on off white for OEM, white on new aftermarket (spectra brand).

Pretty sure on the old one, the filter is bonded to the metal tube with some super duty stuff (?) and it does not or is not suppose come off.

Notice the OEM has a brass float and the new has a what ever it is made of? You can pop out the old out of the arm ring and pop in a new one.