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Gas tank help, please

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OK guys, I need help. Here is a little background. New to me MJ.

The gas tank on my all stock '90 4.0 short bed had been rusted thru and JB Welded before I got it, have no shield plastic or otherwise. Driveability problems, would run for about 1/2 hour or so, then engine would gradually lose power, die down. Pump gets progressively noisier longer it runs.

Pulled the sender/pump mount unit, found strainer etc rusty colored, strainer hose clamped onto rubber at pump (sort of). Inside of tank is very rusty/flaky like.

Also, the mount/sender where the steel line go thru appears that the lines are bent, maybe solder broken. No tapered rubber thing on return.

Probably the biggest problem is that the rubber pump mount(?) is softened up to the point that it will not retain the new strainer.


Sooo, I am looking to you for advice.

1. Is the rubber mount thing available anywhere? The tapered thing?

2. New tank, tray or not?

3. Some other tank? Have searched, but results seem to be for later HO conversions.


:doh: Your ideas/solutions please.

Need to get this thing running dependably.

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A number of things at work here. First off, I wouldn't trust an

epoxied tank, so new tank for starters. Plenty available. Next,

I suggest replacing the fuel filter since it could be partly plugged

with tank crap. You may also need to replace the sending unit

if the tubes are badly bent or solder broken where the tubes

pass thru the plate. That's a leak potential. The tapered rubber

on the pickup tube keeps the tube secure - probably good to have,

and probably can find at JY. Don't know if available new. Once

that's all done, see how it works and run a pressure test at the

rail. Other than the filter, you might find all you need at the JY.

Good luck!

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I agree with everything you have said, only problem is that the nearest place I know that has a MJ is upullnpay, near the airport, and that is a 4cyl, and they punch holes in the tanks to drain.

I'm not opposed to getting a new tank, it's the other stuff that is the problem.

To use the stock tank I need a good guage/mount. And rubber parts. Which in mine are junk. I am guessing it is the ethanol junk being forced on us that has caused things to go spongy.

Was hoping to get some alternatives, what others have done in the same situation.

AND, wondering about using the tank without the trough, does it cause problems on slopes/angles uncovering the pickup?



BTW, save some machine shop money, drill the center of that broken stud, then use torch to burn/melt the remains out of the head. It won't melt the cast iron, and only requires a little thread clean up after.

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I have got two gas tanks from the JY, both had holes punched in them. I just welded them shut. The purpose of the tray is to keep the pick up in gas. The tray keeps it from sloshing and having the fuel pump suck air. For normal driving and keep the tank full, don't go below a quarter of a tank, and you should be OK. There are those who claim never weld a gas tank. That is their opinion. The way I do it is to drain as much gas out as possible, empty it. If you have access to a inert gas, fill the tank with it. Don't use water. Water just doesn't hack it. I use exhaust from a running engine. Run a piece of tubing from the exhaust pipe to the gas tank. With the engine running wait until the tank is warm to the touch. The tank is now full of carbon monoxide which is inflammable and the heat has evaporated all the gas fumes. It's best not to use an older engine for this as the exhaust can accumulate carbon and blow a glowing red piece into the tank before it's cleared out and a nice noisy BOOM occurs. Ask me how I know that. If the tank is warm all over, to the touch it is safe to weld on. If your really opposed to welding, or just don't have the equipment , then solder it. No flame and it works. As for the other stuff, the last time I was at the dealer a couple months ago, I got a half dozen of the 'O' rings and same amount of tubing connects the fuel pump to the filter. It's still available.

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Jim, couple hundred years ago when I lived in Vermont, I have brazed up a number of tanks, using using the exhaust flush method. Only had one go boom, and that was only a mild one!

Is the pump mount/gauge thing interchangeable between the 4.0 and the 4cyl?

And the tank that BMX used is listed as without the tray. Why do they make them with and without? I have never seen a tray in other rigs, just wondering how important it is in the MJ?

I AM correct in thinking the pumps are different between the 2 motors, right?

Thanks for your help guys.

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There is a 8lb pressure difference between 4.0 and 2.5 fuel pumps. I have swapped both ways, 4 pump into a 2.5 and a 2.5 into a 4. Never noticed a bit of difference in the engine running. As for the tray, I believe it was just a "why not? Can't hurt" on the part of the designers.

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There is a 8lb pressure difference between 4.0 and 2.5 fuel pumps. I have swapped both ways, 4 pump into a 2.5 and a 2.5 into a 4. Never noticed a bit of difference in the engine running. As for the tray, I believe it was just a "why not? Can't hurt" on the part of the designers.


;) Actually, I think my pump is good, it's the other stuff, the rubber crap the pump sits in.

Is the gauge/pump mount the same between the two? I know where there is a 4cyl truck. :wall:

When I think of all the places I have been with rigs that don't have a "tray" makes me think it might not be all that necessary. ?

If I get a new tank, it will have a tray, tho.

Thanks Jim

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The tray came on my Eliminator, its just plastic.

Mine got caught while driving down a muddy trail, and bent backwards,

I just tor it off easy.

Its just plastic, i can see it protecting against scratches thats it.


Make or buy a metal tray

I believe your confusing the slosh pan inside the tank with the skid guard located underneath the tank.

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Found out today I'm having tank problems as well there's probably 12 or so pin holes in the tank that leak gas out, I'd normally just try to JB weld the holes but the tanks has a nice bit of surface rust pretty much over 40% of the tank and you can tell there are other holes getting ready to form.


So my options are buy a new tank (my fuel pump is fine) or I was thinking about looking into aftermarket fuel cells that might work.


also thanks to BMXstreet6 for the link. :jump:

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