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Unread 07-29-2009, 10:58 PM   #1
Skinnyfeet
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Dropping the tank on my 79 CJ7

Well, something has been clogging up my fuel lines so it looks like this weekend I'll be dropping the tank and cleaning out the gunk that has accumulated over the years. Does anybody have any tips from past tank pulling experience they'd like to share? I'm no mechanic by any stretch, but Haynes makes it look pretty straight forward.

Is there anything else I should do while I have it out (sending unit??)?

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Unread 07-30-2009, 05:36 AM   #2
Mike1084
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Check the short rubber hoses from the supply and return hard lines to the tank. I found mine had deteriorated pretty badly. As long as the tank is down its cheap preventative maint.
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Unread 07-30-2009, 05:49 AM   #3
UbelGeist
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I would just replace the tank and sending unit while your in there. It isn't that expensive and if you have corrosion in the tank, no matter how many times you go in and clean the thing you are still going to get crap in your filter.
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Unread 07-30-2009, 06:33 AM   #4
CJ7VFR
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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.

Good luck!!

Jim
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Unread 07-30-2009, 06:57 AM   #5
Shasta69
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CJ7VFR

Great post!
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Unread 07-30-2009, 07:24 AM   #6
CJ7VFR
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Its a little long winded, but since this was fresh in my mind from my own tank replacement, my fingers just
kept on typing!!

The most important thing to get right is setting up the sending unit.

The float arm and travel stops, as well as the pickup tube height are important things that need to be set
up BEFORE you mount the sending unit into the tank. Also, you need to make sure the resistance across the
wound core is correct so the gas gauge will read properly from full to empty.

There are write-ups about setting this stuff up as I mentioned. Its not hard, just a multi-step process that
will save you a ton of headaches if you do this before you put the sending unit in, versus having to drop the
tank again!!

don't ask me how I know this...I found out the hard way...

Jim
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Unread 07-30-2009, 02:34 PM   #7
bigjoe
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Only thing I could add to Jim's post and tips is just have a fire extinguisher near by just encase something should happen.
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Unread 07-30-2009, 09:43 PM   #8
Skinnyfeet
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Thanks for the tips guys........especially yours Jim. I took your advice and decided to go ahead and order a new tank, sending unit and filler hoses, even without inspecting the old stuff. I've had the bolts holding the tank/skid plate to the frame soaking in PB Blaster for the last 2 days, and this afternoon I crawled under and they all broke loose without much effort (some good news for a change!). Tomorrow evening I'll get the jack under it and drop the old tank out.

Unfortunately, my replacement tank and the rest of the goodies won't be here until late next week.......hopefully I'll be wheelin' next weekend.

Thanks again........
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Unread 07-31-2009, 06:42 AM   #9
jfwireless
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When I pulled my tank out of my 76 CJ7 it was full of rusty looking liquid, and the tank needed replacing. As soon as I cleaned it out it started leaking, so getting a new tank ahead of time is a good idea.

In addition to the above suggestions, take a look at the strap that holds the tank in place, I needed to replace that as well. You will also need some material to place between the tank and skid plate, I used some flat PVC material from Home Depot used to seal the flooring under shower stalls, otherwise you get two pieces of metal rubbing against one another and here is where the rust starts. I also cut a strip of that flat PVC material to put between the flat strap and the tank.

Jim
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Unread 07-31-2009, 07:09 AM   #10
rixcj
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You can make an access hatch, for the sending unit, for future maintainence, or replacement.

These sending units are known to crap out from time to time...





It's a little bit of work to fabricate, but a lot less work than dropping the tank every time.

Rich
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Unread 07-31-2009, 08:12 PM   #11
Skinnyfeet
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Thats a sweet idea rix.......I may just do that myself.

I got the tank out this afternoon and after looking inside I cant figure out how it ever ran at all. The sending unit has so much rust and crud stuck to it that it barely moves, and the inside of the tank is trashed. I just bought the Jeep 3 weeks ago so everytime I turn a bolt its an adventure, but this is crazy. Now I guess I know why the guy I bought it from said it had been sitting for 3 years.

The bad news is that I cant get the replacement tank until Tuesday so there's not much I can do till then......thanks again for the help.
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Unread 07-31-2009, 08:20 PM   #12
ACAD_Cowboy
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I would highly recommend an access hatch in the bed, it helps the whole process run smoother if you need to get back into the tank to change a sender or drain it. Speaking of draining, you might want to take this time and have a bung welded to the new tank in a protected location, makes draining it even easier if you had to do any welding or torch work in the area of the tank.
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Unread 07-31-2009, 08:52 PM   #13
frankush
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Don't feel too bad about how it looked. Most of them look like that. You would think the vapor alone would keep the tank from rusting. My next tank will be one of the plastic ones.
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Unread 07-31-2009, 09:09 PM   #14
SlikRic
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Quote:
Originally Posted by Skinnyfeet View Post
The bad news is that I cant get the replacement tank until Tuesday so there's not much I can do till then......thanks again for the help.
Take my advise and strip the area of the tank and apply some rust preventitive and a few heavy coats of paint on top of that, and do the same to you skid plate Also check the rear of the frame and cross member while your at it
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Unread 08-03-2009, 03:07 PM   #15
Skinnyfeet
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Quote:
Originally Posted by SlikRic View Post
Take my advise and strip the area of the tank and apply some rust preventitive and a few heavy coats of paint on top of that, and do the same to you skid plate Also check the rear of the frame and cross member while your at it
I started doing that very thing yesterday afternoon........wire brushing everything (jeep is about 95% rust free!!) and then following up with some POR 15 that I had left over from another project. The area around the tank (frame/tub floor) looks great, but the inside of the skid plate will kep me busy for a while. Thanks for the help
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