73 cj5 fuel tank install questions

So I just bought a 73 CJ5 4.2L and the tank was wedged, cracked, and hanging with no bolts. I have purchased a new tank and this may sound stupid, but does the tank mount to the top side of the frame or bottom? I just can't figure out how to get it up over the frame from the bottom.

Next, there's the fuel filler and vent hoses which are pretty self explanatory, but the others are not. Where does the one from the sending unit go and the 2 coming from the opposite side of the filller/vent hoses? Is there supposed to be a return coming from the pump?

Any help and or pictures would be greatly appreciated as I am very new to this kind of stuff.
Thanks!
Kyle

 

The tank mounts to the bottom flange with tabs on the pinch weld of the tank. The flange of the tank sits just above tha bottom flange of the frame. Not all have a return line off it did it would hook to the little line at he sender the two opposite the foley are part of a vapor recovery system. Mine are plugged as I'm missing the parts that they hook to

 

If your 73 is the same as my 75 you should take a look at this
http://www.earlycj5.com/xf_cj5/index.php?threads/liquid-check-valve-location-on-a-75-cj6.115929/
In Timgr's reply he posts a link to the manual. 4-5 shows the setup that is in my Jeep. Check and see if you have the check valve way up inside the driver's side rear fender in the area of the tail lights. Also see if you have a charcoal canister on the driver's side between the front fender and the firewall. Mine also had a return line. It comes from the fuel filter which has one inlet tube and then two outlet tubes. One goes to the carb and one returns to the tank. I will try to get you some pictures but if I can't get to it today I may not be able to for several days.
Also read this thread.
http://www.earlycj5.com/xf_cj5/index.php?threads/75-cj6-fuel-tank-question.111252/#post-1175240
I received lots of good advice here, especially about using U-nuts to mount the rear tank fasteners.

 

All the rear-mounted tanks are basically the same, 1970 through 1975. Almost everything changes for 1976. The main difference over that span is the vapor recovery in 1972 and earlier has an expansion tank under the rear quarter panel, and a vapor pickup line from each corner of the tank. 1973 and newer has a fluid check valve and only 2 connections for vapor, with the pickup lines routed within the tank (not at each corner).

As I recall, you should have a return line in 1973, but I do not have a 1973 TSM to check. If you have a return line, the tank sending unit has a 1/4" nipple that dumps into the tank, and a 5/16" nipple that picks up from the bottom. So you should have 5/16" steel from the tank to the fuel pump, and 1/4" steel return from the third nipple on the fuel filter back to the tank, paralleling the fuel delivery line. The '74 manual does not show a return line, and '73s are almost identical to '74s, except for the badges, colors, some optional equipment, bounce dampening spring in the V8 carburetors, and ... emissions equipment. There is a '74 manual for you to read at the Tom Collins site.

Vapor recovery uses green or black nylon lines. I know that my CA-delivered 1973 CJ-5 had vapor recovery, but the 49-states cars may not have had it. Again, check the '73 TSM.

It seems like it won't fit, but with the right maneuvering, it will go in. The front of the tank is supported by one bracket, and the back sits on top of two angled brackets at the rear corners. Look at figure 4.5 in the '74 manual http://oljeep.com/gw/74_tsm/4-FuelCarburetion.pdf There is supposed to be a rubber insulator between the tank and the frame. I used a rubber stopper cut in half, with a hole drilled through the middle, on my current CJ-6.

 

Ugh, the dreaded fuel tank removal and install.. My least favorite Jeep job.. A floor jack helps out a bunch. I jack my heap up and place it on jack stands, then remove the rear wheels. I place the fuel inlet side up first and then jockey the rest around to get it in place..

 

NB the skid plate is optional '70 to '75. The '76-on tanks require a skid plate, since that's what supports the tank. The '76-on tank sits on the skid plate with straps over it, while the earlier tanks hang from the frame by brackets and bolts, with the skid below them.

If you are missing too many parts, you can go with the later parts where the skid supports the tank. But it will be different from the factory configuration.

 

I replaced the 15 gallon steel tank on a 1975 CJ5 recently. It was a pain but mostly because I bought the cheap Chinese made tank. I really had to do a lot of seam trimming to get it to fit. It was still a much tighter fit than the original tank.