Fuel Tank Issues! Help!

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72DartGuy

72DartGuy

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Hi guys, here’s my problem. I have a 72 Dart Swinger with a 16 gallon tank. My fuel gauge shows really full for a couple of days, then at 1/4 tank it starts to “run out of gas” I go to fill her up and she takes 6 gallons every time. I’ve got 10 gallons that I can’t get to! Anyone know the fix? My sending unit is good and I just took the filter off if the pickup because it was getting sucked up and cutting off my fuel, lmao! What do I need to do to get to the bottom of the tank?
Thanks everyone, and thanks FABO!

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Is the pick-up tube on the bottom of the tank and is it clean?
 
The pickup tube is where it goes. I took the filter off of it and I was able to drive on the freeway without stalling out. I have a motor builder working on my car so I don’t know where the pickup sits in the tank
 
When you described your problem, it sounds like gas tanks has debris clogging the filter causing running out of fuel if so remove and clean or replace as needed, or sending unit is not at bottom of the tank. Assuming you have the stock gas tank in car, you will need to remove the sending unit and when you are inserting it back into the tank before you contact the flange lower the assembly down and see when the tube contacts the tank and adjust the tube as needed you also should get another sock to go on the pickup tube. You also need another filter before the carb, I could not see one in your picture. Nice looking engine.
 
Thanks, we took the sock off. It was sliding up and cutting off all the fuel to the motor. Crazy. Im gonna see what happens when I get down to a 1/4 tank this time. This is basically a new car now. These gremlins keep popping up!
 
"The pickup tube is where it goes" What kinda answer is that? How close to the bottom of the tank is it?
 
Hey bud! It took me this long to get my motor guy to realize (admit) it was a fuel problem. He’s been telling me not to diagnose my car. Yeah, can you adjust the pickup tube? I can only put 6 gallons of gas in my car. My tube is obviously in the wrong place
 
Ha, funny? Dude I’ve replaced everything in this car except for the VIN. If you have an answer I’d love to hear it.
 
72DartGuy said:
Hi guys, here’s my problem. I have a 72 Dart Swinger with a 16 gallon tank. My fuel gauge shows really full for a couple of days, then at 1/4 tank it starts to “run out of gas” I go to fill her up and she takes 6 gallons every time. I’ve got 10 gallons that I can’t get to! Anyone know the fix? My sending unit is good and I just took the filter off if the pickup because it was getting sucked up and cutting off my fuel, lmao! What do I need to do to get to the bottom of the tank?
Thanks everyone, and thanks FABO!

View attachment 1716086403
Click to expand...
Okay, let's start at the beginning.
You're saying you have 10 gallons left when the sender is on "1/4". And it registers "Full" for an exceptionally long time.
You have a float issue.
When installing a new sender/pickup (especially some of the new repro ones of dubious quality) it is imperative that you check and adjust the float sweep if necessary. this involves nothing more than bending the arm of the float.
To do this, you need to remove the tank. Install the new sender, and using a flashlight (not the old joke about using a lighter) look in through the fill tube hole and see where the float is. If necessary, reach in with a coat hanger and move it to make sure it can move up and down unobstructed. In your case, I'm going to guess it comes to rest about mid-tank. It needs to come to rest maybe 1-1 1/2 inches from the bottom (just so you've got a bit of "reserve" in the tank when you hit "E"). make a note of how far you'll have to adjust it, and remove the sender again. Now bend the float rod downwards the amount you you've noted, and check that the float arm still moves up and down freely. Reinstall the pickup and check float operation. Readjust if necessary.
The pickup tube should be at or very near the bottom of the tank. Adjust if necessary by bending the tube. Do NOT run it without a filter sock. I understand the sloppy fit of some of the available pieces, all you need to do is put a small stainless steel hose clamp, or even a short piece of snug-fitting fuel hose, on the tube in such a location as to prevent the sock from being able to slide up the tube enough to block off flow. Some aftermarket socks even have a small flat area on them to be able to clamp them directly in place.
 
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I had a problem with a replacement unit. I took it out removed the sock, It too was sucking to the end of the tube. I held the unit and measured from the mounting surface to the bottom of the reach down of the tube. Bent it to approximate the same depth I needed to reach the bottom of the tank .

I went to deep so it wouldn't sit flush in the ring of the tank hole. I bent it up a tad until it would sit flush. Once I got it to fit I cut the end at a V so noting could ever suck onto it.

Now that was corrected I focused on the sender. While out of the tank I ground it with a long wire and attach another long wire from the sending unit plug. Hold it while sitting in the car. Make sure the float is at the bottom of the pick up tube, You may need to bend the wire down.

At this position with the key on, The tank should read empty. As you move it up you will see where the gauge travels to at different heights. Worked for me in several builds. They never seem to be correct when you get them. But with some persuasion you can fix them. I had one I got on ebay from chink land where I needed to add a resister. Never went to empty on a gauge. Always had current flow.

Oh and I never had one out of the box I bought that reached the bottom of the tank to this day. All needed to be bent down . Some more then others.
 
Common issue!

New Sender/Pickup old tank? Or new Tank old Sender? Or both New?

Answer these questions and more help is available.
 
Oldmanmopar said:
I had a problem with a replacement unit. I took it out removed the sock, It too was sucking to the end of the tube. I held the unit and measured from the mounting surface to the bottom of the reach down of the tube. Bent it to approximate the same depth I needed to reach the bottom of the tank .

I went to deep so it wouldn't sit flush in the ring of the tank hole. I bent it up a tad until it would sit flush. Once I got it to fit I cut the end at a V so noting could ever suck onto it.

Now that was corrected I focused on the sender. While out of the tank I ground it with a long wire and attach another long wire from the sending unit plug. Hold it while sitting in the car. Make sure the float is at the bottom of the pick up tube, You may need to bend the wire down.

At this position with the key on, The tank should read empty. As you move it up you will see where the gauge travels to at different heights. Worked for me in several builds. They never seem to be correct when you get them. But with some persuasion you can fix them. I had one I got on ebay from chink land where I needed to add a resister. Never went to empty on a gauge. Always had current flow.

Oh and I never had one out of the box I bought that reached the bottom of the tank to this day. All needed to be bent down . Some more then others.
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I like the idea of V- cutting the pickup tube!
 
That’s what I needed to know! You guys are awesome. It’s an old tank with an old sender. Literally everything else is new. Should have changed it too. But float and sender are the problem. Thanks for the advice guys!

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You've spent a bit on this car if it has a 408, but you're driving around with a 53 year old gas tank? You can get a new reproduction tank from Quanta and they are pretty cheap, completely clean and uncorroded. While it's out you can fit the sending unit/pick-up and hear it tap the bottom in the tank so it's easy to get it in the right place.
 
Oldmanmopar said:
I had a problem with a replacement unit. I took it out removed the sock, It too was sucking to the end of the tube. I held the unit and measured from the mounting surface to the bottom of the reach down of the tube. Bent it to approximate the same depth I needed to reach the bottom of the tank .

I went to deep so it wouldn't sit flush in the ring of the tank hole. I bent it up a tad until it would sit flush. Once I got it to fit I cut the end at a V so noting could ever suck onto it.

Now that was corrected I focused on the sender. While out of the tank I ground it with a long wire and attach another long wire from the sending unit plug. Hold it while sitting in the car. Make sure the float is at the bottom of the pick up tube, You may need to bend the wire down.

At this position with the key on, The tank should read empty. As you move it up you will see where the gauge travels to at different heights. Worked for me in several builds. They never seem to be correct when you get them. But with some persuasion you can fix them. I had one I got on ebay from chink land where I needed to add a resister. Never went to empty on a gauge. Always had current flow.

Oh and I never had one out of the box I bought that reached the bottom of the tank to this day. All needed to be bent down . Some more then others.
Click to expand...
Excellent info!
 
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