Can I install a new fuel sender unit on a 72 duster without removing the tank?

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jcolman

jcolman

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I filled up my (new to me) duster tonight and the tank started leaking like crazy wile I was still at the pump. I drove the car home and parked it in my gargae and now it's barely leaking but obviously I need to fix this. The gas gauge doesn't read "full" so that leads me to suspect the sending unit has failed and/or the gasket is leaking.

I could take my car to my local speed shop (who does great work but pricey) to have the job done. However, if this is something I can tackle myself I'd like to try. I know I have to get most of the gas out of the tank so I guess I'll be cruising around this weekend to burn some of it off (hey!! not a bad way to spend a weekeind right?!)

So if anyone can point me in the right direction I'd appreciate it!
 
Can you tell where the leak is coming from exactly? Are you sure it's not the filler neck where it goes into the tank?
You are better off pumping the tank down into containers rather than burning the fuel.
 
crewchief said:
Can you tell where the leak is coming from exactly? Are you sure it's not the filler neck where it goes into the tank?
You are better off pumping the tank down into containers rather than burning the fuel.
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Good question. I really don't know as it was getting dark when I fillied it. I was talking to a guy who pulled up to admire my car just as I finished filling the tank. While I was talking to him, I noticed fuel leaking from around the tank. I looked under the car and saw that it appeared to be coming from more than one location, but I coulnd't be sure. At first I thought my tank seams were leaking but it was hard to tell. I probably leaked a good cup or two of gas on the ground. After I got home I started searching the forums for clues which lead me to believe the sending unit might be leaking. Tomorrow I'll crawl up under the tank and take a closer look so I should have a better idea where the fuel is coming from.
 
If the gas guage is off there is a chance someone replaced the OEM with a "new" one

New ones have two problems
First off, they are linear, while the OEMs are not
So an aftermarket sending unit will NEVER read right on its own

Secondly, the new ones also come with a new locking ring, which is somewhere in the neighborhood of half the OEM thickness, and therefor, prone to leak

So, if tomorrow, you get under there and the locking ring is nice and shiny, you may very well have found the issue


As for removing it with the tank in place..piece of cake

Expect the first one to take about 30 minutes
After doing it a few times, you can R&R one in about 15

My rule of thumb is no more then half a tank and it won't spill

(Because the sending unit sits in the side of the tank, and not on top, it will gush out if you do this on a full tank)
 
As stated, reuse the lock ring and get a new seal from Detroit Muscle. To make life easy by a lock ring tool. Reason being is banging on the lock ring will cause the lock ring and sending unit to shift and leak, tool prevents movement.
 
yes totally agree on the lock ring tool. I just replaced my tank and even the new AMD supplied ring of questionable thickness was hard as heck to get turned all the way into place. had to hammer the tangs where the tool can put even stress on all 3-4 and just turn them in with its long handle. Probably use it 4 times in 20 years but worth it.
MF293 - 1962-76 Mopar Lockng Ring Install Tool
 
I recently got a lock ring tool and man what a difference it makes. Without the tool its hard to keep everything centered and the lock ring wants to bind.
I have used the new lock rings and never had one leak yet, guess im just lucky. They are definitely thinner gauge than the original ones.
 
You can, but why would you? If the sender is faulty, it could be rusted badly and the rest of the tank could be a mess and need cleaning out. Also would give you a grand opportunity to inspect the tank. I'd pull it. It's a 15 minute job.
 
RustyRatRod said:
You can, but why would you? If the sender is faulty, it could be rusted badly and the rest of the tank could be a mess and need cleaning out. Also would give you a grand opportunity to inspect the tank. I'd pull it. It's a 15 minute job.
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ABSOLUTELY CORRECT. There is a right way and a wrong way to do this. Since the car is new to you, you have no way of knowing what shape the tank is in. RRR might be exaggerating a bit when he says it is a 15 minute job, maybe I'll drive to Georgia and time him on a gas tank removal, but it really doesn't take long. Then you can pull the sending unit and thoroughly inspect the inside of the tank. Clean it out, or get a new tank, if yours is really gross inside. If it is the original sending unit, have it rebuilt. Everyone on this forum seems to think that is best. Otherwise, I would get a new one. I know a lot of people have had trouble with the new ones, but I got mine from Classic Industries, and it works great. Then you will have the opportunity to install the new sending unit with the new seal and install a new filler neck seal. No more leaks AND you absolutely know about entire fuel tank.
 
harrisonm said:
ABSOLUTELY CORRECT. There is a right way and a wrong way to do this. Since the car is new to you, you have no way of knowing what shape the tank is in. RRR might be exaggerating a bit when he says it is a 15 minute job, maybe I'll drive to Georgia and time him on a gas tank removal, but it really doesn't take long. Then you can pull the sending unit and thoroughly inspect the inside of the tank. Clean it out, or get a new tank, if yours is really gross inside. If it is the original sending unit, have it rebuilt. Everyone on this forum seems to think that is best. Otherwise, I would get a new one. I know a lot of people have had trouble with the new ones, but I got mine from Classic Industries, and it works great. Then you will have the opportunity to install the new sending unit with the new seal and install a new filler neck seal. No more leaks AND you absolutely know about entire fuel tank.
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Yeah ok. If the tank is full, you gotta drain it. So maybe 25 minutes.
 
Some of these tanks have none to a few emission nipples for EVAP. Other than the fill neck seat and sending unit seal, that's another area to look at.
There is a short rubber hose that connects the sending unit to the fuel line, could also be suspect. If its a older hose, todays fuel will eat through it over time.
 
Thanks guys for all the suggestions! Much appreciated! I crawled under the car this morning and it appears that it is indeed the fuel sending unit that is the problem. The rubber hose that connects to the fuel line looks to be new so I don't think that's the issue.

I'm having the fuel system converted from carburetor to EFI. The parts have been ordered but as usual, everything is on back order. Once all the parts on in, the tank will have to be dropped at that point anyway so the shop can install a new electic pump. We can sort out any other tank issues at that time.

In the meantime, I'm not going to fill the tank all the way. I'll drain out some of the fuel. I'm trying to decide if it's worth the trouble to order the necessary tool and gaskets or just wait unti the car goes into the shop for the EFI conversion.
 
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jcolman said:
Thanks guys for all the suggestions! Much appreciated! I crawled under the car this morning and it appears that it is indeed the fuel sending unit that is the problem. The rubber hose that connects to the fuel line looks to be new so I don't think that's the issue.

I'm having the fuel system converted from carburetor to EFI. The parts have been ordered but as usual, everything is on back order. Once all the parts on in, the tank will have to be dropped at that point anyway so the shop can install a new electic pump. We can sort out any other tank issues at that time.

In the meantime, I'm not going to fill the tank all the way. I'll drain out some of the fuel. I'm trying to decide if it's worth the trouble to order the necessary tool and gaskets or just wait unti the car goes into the shop for the EFI conversion.
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I just now looked at your avatar and realized the car we're discussing. As in the other thread I mentioned this in, I am almost 100% certain this car belonged to a member here. Did you ever determine that?
 
RustyRatRod said:
I just now looked at your avatar and realized the car we're discussing. As in the other thread I mentioned this in, I am almost 100% certain this car belonged to a member here. Did you ever determine that?
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Not yet. I've sent the dealer I bought the car from my contact information to pass onto the previoius owner. I'm hoping that this person will contact me.
 
If you are going to fuel injection, you may want to consider a new tank with an in tank fuel pump.
 
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