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Discussion Starter #1
Hey gents, so I dropped my fuel tank (after running it as low as I could...)

I replaced the fuel lines and the filler lines because of a fuel smell. Cleaned up the rust on to of the sender unit but really didn’t move or adjust much more.

This is a 89 4.2 carbureted wrangler with 20 gallon plastic tank. The two fuel hoses are 3/8 and 5/16 so they weren’t accidentally swapped.

Now it did start and run for a few miles after buttoning it back up- drove it for about 5 miles to go get gas and back home. It’s only after I go to leave for work this am that I drive half a block and it dies. It cranks and does everything except start. My plan is to take the line off the carb and see if it’s getting fuel, but I’m slightly lost as to how to remedy or fix this after that point. I’m expecting it to not get fuel

Any help would be appreciated- thanks!
 

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Discussion Starter #3
With all of the disruption of stuff you could have plugged up the fuel filter. As you planned, verifying fuel from the pump would be the first step.
So changed that for a quick shot and no go. Fuel poured out of both ends when I removed it too. I suppose the next is to disconnect the line from the carb but i left my tools in my fathers garage so I can’t hit that at the moment.

How could this run fine for a few miles and then suddenly shit the bed? It’s *got* to be a fuel delivery issue...🤔
 

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Discussion Starter #5
I figure I’m going to have to go through the whole fuel air spark gambit to at least figure where the issue is, but I’ll have to wait until tomorrow to do it.

On a side note when I turn the key I can still hear the unit in the tank operate. Maybe I’ll see if I’m still getting fuel in that filter tomorrow and then I’ll start to chase it up to the carb.

*edit*

So after installing the new fuel filter and several opportunities to turn it over I removed to newly installed fuel filter to check and there’s no fuel. I also cranked it when the filter was disconnected and no fuel anywhere. There must be a pinched line somewhere between there and the gas tank.

Best part about dropping the tank (again) is now dealing with the 20 gallons of fuel I just recently put in there...
 

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I'm lost on the Hearing the fuel unit work in the tank. your 4.2 should be fed by a mechanical pump, if somebody installed an electric pump in the tank its possible that there is something going on inside the tank.
If you are running a mechanical pump, You can check your fuel output by disconnecting a fuel line at the filter, adding a length of hose to the filter and cranking the engine. you should get a slow pulsing flow out of the line if your running mechanical, if you are actually running an electric pump it will be a steady flow with a lot more pressure, so be careful with that.

Which pump do you have?
 

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Yeah.... I missed that. If you are running a newer tank possibly with an electric fuel pump it would be giving your carb way too much fuel. Back to the original post... 2 fuel lines. A carb would not have a return line, just a feed. Something strange is going on here.
 

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Discussion Starter #8
I'm lost on the Hearing the fuel unit work in the tank. your 4.2 should be fed by a mechanical pump, if somebody installed an electric pump in the tank its possible that there is something going on inside the tank.
If you are running a mechanical pump, You can check your fuel output by disconnecting a fuel line at the filter, adding a length of hose to the filter and cranking the engine. you should get a slow pulsing flow out of the line if your running mechanical, if you are actually running an electric pump it will be a steady flow with a lot more pressure, so be careful with that.

Which pump do you have?
My mistake. I have the mechanical fuel pump.
 

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Yeah.... I missed that. If you are running a newer tank possibly with an electric fuel pump it would be giving your carb way too much fuel. Back to the original post... 2 fuel lines. A carb would not have a return line, just a feed. Something strange is going on here.
Daddyjeep, The 4.2 fuel system has a return line, from the backside of the fuel filter two outlets, one supply to the Carb, and a return to the fuel tank. We carb folks generally put a restrictor in the return line to force more pressure to the carb supply line.
 

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Sly, There's a dozen different ways to drain your tank, definitely don't want to try and maneuver it full. But I'd make sure it's not the tank first, slim chance that your fuel pump died the same time you worked on the back end, but...

If you can start and idle but not accelerate you have a restriction in the line, If it won't start at all then you are fuel starved and not getting fuel at all.

If you have to drain your tank and it idles, the pic shows where I disconnect the fuel return line, add a hose to a gas can and drain my tank. No smoking and no sparks....Empties it completely.
 

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Discussion Starter #12
Ok so sure enough it would seem we are getting fuel delivery! I started checking a few lines on the underside and they were full of fuel. Tried cranking it for a bit again and the fuel filter is pouring out fuel now, so I suppose that’s a positive thing.

*edit*
Disregard photo
So with enough moxy I was able to get
It started. It’s quite stubborn to start, but I did manage to do it several
Times.

Now the vehicle will reverse just fine. When I put it into first and try to go it dies. It does this repeatedly.

Do the soft fuel lines on the underside need to be secured or something? Maybe it’s pinched by where it mounts on top of the tank but it appears to move quite freely when I’m on the underside of the jeep
 

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Discussion Starter #14
I think a fuel line is pinched between the tub and the gas tank. It’s the only way it’s could be starving for fuel.

I’m draining it as per got t at last (super helpful way to drain t btw- thank you) an dim goig to drop the tank and have a look see.

On a side note, while it’s draining I can see plenty of air bubbles in the line- is that normal or indicative of anything?
 

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some years ago i had a problem with 4.2 Was nuttered, with Carter carb. After running the tank empty it started when cold, idled fine, sometimes hot start problem, from idle to 2500 rpm it ran ok, but it starved for fuel when floored.

At the end the filter sieve inside tank was clogged and the suction hose was dettoriated. Dropped the tank, removed the fuel sending unit, replaced the hose and filter sieve and all good.
 

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Discussion Starter #16
Ok so time for an update.

Nice thing about having a lifted Jeep is being able to get under it really well. I was able to trace the fuel lines back by hand and they’re just “hanging around” so to speak- figure about 3 feet of fuel line. It appears that in the course of driving it doubled back on itself perhaps just slightly enough to cause fuel starvation. I zip ties them and secured them in place in hopes of preventing that. Went for a quick spin up and down the block and the issue *APPEARS* to have been resolved.....

Keeping my fingers crossed, I hope I’ve licked it
 

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Sounds like you've got it licked, but I've drained my tank a couple times to drop it and had no bubbles while draining, since you started this project due to gas fumes, wondering if maybe you don't have a crack in a line somewhere...Where are you on the fume issue now.
 

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Discussion Starter #18
There’s certainly less fuel fumes- whether there is any? I’ll have to wait to get feedback from the wife.

The difficult ones are done. I have t changed the fuel lines in the front of the Jeep yet, so that could have a small crack.

I’m getting there slowly, but surely. Hopefully ill have my settlement for my last jeep come next week (tractor trailer sideswiped me and is trying to deny my claim) and with all that extra cash I’ll be able to buy a shitload of parts for the Jeep-
 
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