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Discussion Starter · #1 ·
I have an 85 cj7 with a leaking fuel tank. When I dropped the tank I noticed the drain holes in the skid plate were plugged with rust scale. There is a plastic shield there that insulates the tank so it's not metal to metal. The problem is the plastic was cracked in 3 places and I can't bring myself to re use it. So my question is what can I use instead? I read that the plastic piece isn't easy to find so I was thinking of painting the inside of the with an under coating or a roll on bed liner. Also if I do is it safe?

Any info is helpful, thanks in advance

1,069 Posts
Cut a piece out of a rubber bed liner. The ones that are like a rug that just lay in the bed. Think the farm stores have them.

Premium Member
11,200 Posts
Rubber conveyor belt material will work fine, but I use HDPE (High Density Polyurethane), it's cheap and cuts fine with a razor knife or hack saw.
You can find it at industrial stores like Granger or on the internet.

Do yourself a favor and drill some holes in it, fairly large, about 3/4" or larger for drainage.
These liners like to hold mud/crud/moisture against the tank...

I'd also spray/roll that tank with a rust proofer and some urethane coating of some kind.

The HDPE doesn't hold moisture or crud like rubber will, easier to clean,
But if the crud builds up there will be no difference between rubber or HDPE.
Moisture laden mud is moisture laden mud and it's going to be abrasive and it's going to cause rust.


While you have the tank out...

SOLDER a lead wire onto the sending unit tab.
And also SOLIDER a ground wire to the sending unit somewhere on the metal.
Use silver bearing ELECTRICAL SOLDER, and seal up the connections.

These leads will let you connect your sending unit to the gauge OUTSIDE the tank/frame,
And the 'Ground' will make sure your sending unit actually WORKS the way it should.


Suction line on the sender/pickup tube will have a 'Sock' or 'Screen' attached to the bottom that is 'Supposed' to adjust to the depth of the vehicle's tank...

Anyone that has done this very often knows it either flattens out on the bottom of the tank and creates a suction seal,
Or the pickup doesn't reach the bottom of the tank... And your 13 gallon tank becomes an 8 gallon tank...

I've started stripping off the 'In Tank' filter all together...
I slip a piece of Steel or Copper tubing over the 'Down' tube (Suction line) and dimple it so it's a friction fit.

Then install it into the tank.
The bottom of the tank will push that dimpled slip fit up as it hits the tank bottom and you have a SOLID suction line that reaches the bottom of the tank.

Carefully remove the sender/suction assembly, and move the tube you added UP about 1/2 inch for suction clearance.
Then SOLDER that tube onto the suction tube.
(Some people use rubber fuel line here, I don't want anything in the tank that can fall apart, like that plastic suction 'Filter' or 'Sock' that comes with the sender...)

With a 1/2" at the bottom for fuel clearance, then about 1/2" up, drill two or three holes in the side of your suction extension, or cut some inverted 'V's in the sides of the suction tube.
This will give you suction to within 1" of the bottom or so, and if the tank gets dented up, the holes/'V's on the side will still allow plenty of fuel into the suction tube.

Pull a piece of brass screen up over all the holes. I usually do about 3" inches with a 'Bulb' on the bottom/suction opening end.
Use a METAL 'Zip' Tie or small STAINLESS STEEL hose clamp to hold it in place if you aren't too good at soldering, if you are proficient at soldering, just solder the brass screen to the copper or steel tube you installed.
(Copper solders nicely here...)
Brass solders nicely to copper, a little more difficult for steel, But you can burn up fine screen if you use open flame soldering, and it's hard to do something this size with an electric soldiering iron.

The screen is not going anywhere once installed, so this isn't critical, and the 'Bulb' at the end lets plenty of fuel into the suction line...
The brass screen will keep the big chunks of rust out of the fuel system, or anything that might make it down the fuel filler hose...

Now you have a sender/suction that actually FITS the tank you are using.
I'm not shy about using a SUCTION LINE fuel filter either. If it's a hard case filter, it won't make a difference to the fuel pump.
That will keep the smaller crap in the tank/lines from getting wedged in the fuel pump.
My line filter is usually at the fuel pump inlet, just easier to change that way...


The next issue is getting the gauge to read 'Correctly'...

BEFORE you do final install in the tank,

With gauge sender wired to the correct wire in your Jeep harness,
And a SOLID ground to the sender... And some LONGER WIRES to the tank/sender,
Turn the tank up side down to simulate 'FULL' and watch your gauge.
Then turn it right side up and watch your gauge...

This will give you a good idea if the 'Float Arm' on the sender is doing what it's supposed to do.
I'd say about 75% of the senders I install need to have the float arm BENT to make them reach either full or empty.
They usually don't come bent correctly...

Now, it takes a little messing with, taking the sender in and out to get it right,
But you already KNOW if the gauge is going to work correctly.

If you bought one of the senders with a 'Plastic' float,
And the float from your old sender is brass, or you can locate a brass float, use the brass float!
Those damn replacement plastic floats like to quit on you in short order.
Why they would make a float that decomposes in fuel for a fuel tank application is beyond me, but they do!
Nothing like having a gauge quit on you (OF course with a full tank!),
Pulling the tank AGAIN, and finding what's left of the plastic float decomposing in the fuel!

Just some tips from a guy that has had way too many tanks/sending units out of a vehicle!
We all know nothing goes wrong until the tank is FULL!

3 Posts
Discussion Starter · #6 ·
Wow! JeepHammer that's is really good information that I hadn't considered. I'm going to look for the HDPE as it sounds like a just what I need. I never really had issues with the sending unit but I'm sure I will once I mess with it. I do recall that I ran the tank down on empty for while and it still had 3 gallons in it so I'll try the process you outlined in your post and extend the suction tube.

Thanks for the info!
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