The rubber lines connecting the tank sending unit to the metal underbody lines have developed a leak and need to be replaced. These lines include the fuel supply line, return line, and tank vent. I’ve already disconnected everything and removed the tank, but I’m struggling to remove the three lines. They’re bundled together and tightly wedged between the body and a crossmember.
My question is, do I need to loosen the nearby body mount and slightly lift the body to remove these lines?
Thanks.
Yes, I removed mine just a few days ago.
I loosened the closest body mount and the one behind it. Then, I used a prybar to slightly lift the body and had to pull quite hard to get the lines out. There’s black duct tape around the rubber “grommet” block, which likely fused to the crossmember. That’s what you’ll be pulling against when you lift the body with the loosened body bolts.
Over time, the tub-to-frame fit becomes tighter as the rubber body mounts wear down. Even a small 1/8" sag in the old rubber mounts can cause the issue you’re experiencing. When I last removed the body, I added some 3/8" woven rubber mat disks I made, which provided just enough clearance in the fuel area to resolve the problem. The metal of the tub at the front-most mount (not the grille) can also touch the top of the frame as the mounts deteriorate. My fix addressed that issue as well. If your Jeep has spent its life in Arizona, you’ll likely have minimal issues with the tub bolts.
Ensure that you’ve connected the correct hoses. If I recall correctly, the larger hose is the supply line, which connects to the fuel filter. Additionally, since you had trouble removing the lines from the crossmember, they might now be pinched. I replaced that sponge piece with hard lines in that area to avoid similar issues.
Yep, that’s what I was thinking too. But the hoses are indeed hooked up correctly. I’m starting to think (desperately hoping in fact) that I just didn’t crank it long enough to re-pressurize the system. I’ll give it another shot tomorrow.
Get underneath the vehicle, disconnect the hose before the fuel filter, and attach a longer hose to the steel line. Place the end of the hose in a container, then cycle the key a few times. If the pump runs but no fuel comes out, the fuel hoses are likely connected backwards.
Finally got her started. I think it was a combination of issues:
Once these issues were addressed and everything put back together it started right up. Thanks for your help.
I recently got my '89 YJ 4.2L, and the previous owner replaced the two-outlet fuel filter with a single outlet to the factory carb, while pinching off the return line—I’m not sure why. The engine seems to run fine, and I haven’t noticed any issues with fuel consumption; it seems normal. I can’t tell if it’s delivering more fuel than needed (running rich) or if the mechanical fuel pump compensates for excess pressure downstream. The fuel fill vent was also broken, so I’m replacing the tank and all the fuel lines. I’ll restore the system to its original setup with a fuel supply, return line, and vent line to the canister unless there’s a reason the return line isn’t necessary.
I don’t think the mechanical fuel pump has an over-pressure relief feature, which means the float valve is the only thing stopping the fuel. As far as I know, having the return line is a good idea. It helps prevent fuel from vaporizing in the line by constantly delivering cooler fuel.