Don't be surprised if your tank is rusted on the inside, and needs to be replaced. If there is gunk and crap
in the fuel system, its usually from rust and corrosion inside the tank coming loose, not from the gas.
You may want to buy yourself a new tank ahead of time if you use your Jeep as a daily driver. If not, you
can take the old tank out, see if its worth cleaning and reusing it, and then put it back in after its cleaned up.
But my bet is that your tank will need to be replaced, so be prepared for that.
To take the tank out, I would use a jack, with a 2 foot long piece of 2x4 on it to help lower the tank down
once you get the bolts that hold it to the frame loose.
Unless you empty the tank, the added weight of the gas can make the tank very heavy. By using the
jack, you can lower the tank slowly, and make sure that nothing is binding, or keeping it from coming
out. And, you can slowly roll it out from the back of the Jeep on the jack and not bust your gut trying to
lift and pull it out.
Also, make sure you disconnect ALL the lines that go to the tank before you take it out. There will be fuel
lines and the electrical wiring that goes to the sending unit that you need to be careful of when you lower
the tank, as well as the gas filler and vent tubes, and any fuel line hoses that attach to the tank for venting.
If this will be the first time the tank has ever been out of the Jeep, you will probably have to cut
the gas filler tube and the rubber vent tube that is underneath that if your Jeep has one, like my 1985
CJ-7 (15 gal tank) did.
The rubber fill and vent tubes are going to be dry, and cutting them out, and replacing them with
new ones will be faster, and easier than trying to pry the old ones off and saving them.
Also, yes, get a new sending unit. Your tank might have 30 years of gunk in it, and in almost every
instance, removing old crusty sending units will destroy them. If you have a new one already to go
into the tank BEFORE you are ready to put the tank back in, you will save yourself a TON of headaches
and waisted time. Make sure you get ALL the sending unit parts, including any pickup line filters and floats.
Also, make sure to set up the new sending unit so it will read properly when its installed. You don't want
to have to do this twice!! Do a search of this site to find out how to do that. Its not complicated, but its
a multi-step process, and requires slightly different calibrations for different year Jeeps.
You will also want to buy some lengths of rubber fuel line hose to replace the old lines. You can wait to
get the fuel line hose until you get the tank out of the Jeep. Then, you can see what sizes you will need,
and what lengths you need by comparing it to the old ones. On my 1985 CJ-7 (15 gal tank) I had two
different diameter fuel hose sizes. One for the line out to the fuel pump, and one for the venting system.
Also, you may want to check on the rollover and check valve lines to see if they are hard and crusty, and
may be in need of replacing. They should be located up behind the back wheel on the drivers side of the Jeep,
on the brace that is attached between the wheel well and the body. These lines go unchecked alot of times
because people forget they are there. The roll over valve is metal, and the check valve is plastic. Be
careful cutting the hoses off of these two valves. You don't want to break the hose barbs on them, as these
part is VERY hard to find now, if you can find them at all.
You should also get a new fuel filter to have ready, and even a new fuel pump if yours is old.
When you remove and then reinstall the tank, you will loosen up some crap in the fuel lines that can get sucked into the
fuel pump and fuel filter. And since you have already said that your fuel lines are clogging up, your
fuel pump and fuel filter are probably clogged up too. Get new ones and eliminate one more problem
with your fuel system!
When I did my new tank install, I ran the Jeep for a few minutes with the old fuel pump and fuel filter on it,
and then changed them the next day. This way, any crap that I loosened up was now trapped in the
old parts, and my nice new parts would stay nice and clean!
If you have all new parts, the job will go alot easier than trying to clean and fix old rotten ones.
Also, be careful NOT to smoke, or make any sparks or use any steel objects to strike the tank if you
take the sending unit out of the old tank. Just one spark can blow you and the tank to hell!!
If I was you, and this is the first time the tank has been out of the Jeep, I would buy a new tank, sending
unit, filler and vent hoses, fuel line hoses, fuel pump and fuel filter for your Jeep. It would be a real pain in
the *** if you tried to clean up the old parts, put them back in, and then you find out you still have a fuel
flow problem, and have to pull the tank a second time.
Do the job once, and do it right.