fuel gauge reads wrong

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beerboy

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my gauge reads E, i go to fill up. takes about 8 gallons. gas tank and sending unit fairly new not stock, i have read other threads on this and seems to be a common deal. any how my car wiring ability is not that good , either is working on a sending unit. question is should i start by replacing the repo unit? there is one on ebay now that looks to be more like the oem unit, longer arm and such, the price reflects it. temp gauge works , gas gauge works just not correct. should i start with that? voltage limiter must be working or temp gauge would be out. car is a 73 340 duster thanks for any info!
 
you mean at the sending unit itself. in simple terms, how should i check it? thanks much
 
There is a strap from the sending unit to a ground point, all these gauges are screwey, I learn where empty is and go with it.
 
beerboy said:
you mean at the sending unit itself. in simple terms, how should i check it? thanks much
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I would just get a jumper wire with alligator clips on it.

Then clip it to the tube coming out of the gas tank and then a body ground (make sure to clean off any rust before checking). Then see if the gauge reads better.


(Kinda like over-grounding.)
 
Very Rare that one reads accurate. Mine reads just like yours and it is Brand New. I know what the gauge means. I leave full, get to destination and fill it up again! Always keep it full..........
 
I will try the ground thing and see where it goes. I don,t want to change the sending unit and get the same deal, looks like a lot of guys tried that and I didn,t work.
 
I forgot to say that before I do anything when the needle drops to E and I pump in those 8 gallons the needle goes to full, but drops pretty fast. so I ,m thinking that the guage is working and its the sending unit?
 
First thing to do is figure out if the gauges are accurate. The oil, fuel, and temp all use the same resistance. Find yourself some test resistors, and hook from the gauge wire to ground, turn the key to "run" and wait about one minute

http://www.forabodiesonly.com/mopar/showthread.php?t=179517

The test resistors are

L = 73.7 Ohms (empty)
M = 23.0 Ohms (1/2)
H = 10.2 Ohms (full
 
I think the reproduction aftermarket sending units have a pickup point that is higher than originals. So you run out of gas with quite of bit of gas left in the tank.

I've run out and filled 14 gallons. I've run out with the original sender and put in 17+ gallons.
 
beerboy said:
I will try the ground thing and see where it goes. I don,t want to change the sending unit and get the same deal, looks like a lot of guys tried that and I didn,t work.
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Sender is up against hold down. Tank has straps holding it in place to ground. I doubt grounding it more is going to help you. It is grounded.
 
mad dart-- I would say you are correct. I mean the temp gauge works, oil pressure is a separate mechanical SW type, and the gas gauge works, just not reading right. the previous owner put the gas tank and sending unit in. I don,t know if he used the Taiwan cheapy with the plastic float. I am seeing that these can be bad right out of the box
 
With today's repop sending units, the ohms are only tested in the full and empty positions. If they meet those specs, they pass "quality control". In the past, they were tested through the full range of the sending unit and had to be accurate through the full range to pass.
 
if I do go for a new send unit any one know where I can get a mopar oem unit? or whats the best repo unit out ? I would rather pay whatever more and have it work right
 
There is a ground strap that needs to be installed. It clips on the fuel tube at the tank and onto the line going front. It makes a connection where the rubber hose dosen't.

I eliminated my factory fuel line on my tank and put a sump in it. The gauge no longer worked. What I did was drilled a hole in the very corner lip of the tank and ran a ground strap to the body. It now works fine.

If you do not have the factory clip on ground strap. yo will have to ground the tank. Do not rely on the tank installation straps . Mine did not make a good ground through them. Steve
 
steve, the gauge is working , but giving an incorrect read.i mean the needle reads full and the tanks is full but 70 miles or so later it gradually drops to empty. fill up and it takes 8 gallons or so and needle back to full, so I think its the sender. your saying bad ground could do this?
 
The simple way to learn if a different sender will solve it is to try it.
Good luck
 
redfish. I hear year one sells good ones ? there is one on ebay now for like $109. I said why so much? he says it is all stainless steel, and is licensed by mopar. do I believe that? I mean never having to buy one , is it the get what you for pay for type thing?
 
beerboy said:
redfish. I hear year one sells good ones ? there is one on ebay now for like $109. I said why so much? he says it is all stainless steel, and is licensed by mopar. do I believe that? I mean never having to buy one , is it the get what you for pay for type thing?
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Mopar License means nothing.

Look at a picture of the part. If it looks like your old one...well.

Read some info here. This guy might be doing A-body ones in 3/8"... http://board.moparts.org/ubbthreads/showflat.php?Cat=0&Number=8057673&an=0&page=0#Post8057673

Frankenduster said, "the 3/8" one in the car now from Year One in 2002. It has always read 1/4 tank less than what is in the tank"
 
autoxcuda, I don,t have a lift or access to one, I would have the mechanic I barter with do the job. so the parts still in the car and I have no way of taking it out myself. so I don,t know if its a 3/8 or 5/16 either. i think i would trust year one over that ebay dude. well i will keep on trying here.
 
beerboy said:
redfish. I hear year one sells good ones ? there is one on ebay now for like $109. I said why so much? he says it is all stainless steel, and is licensed by mopar. do I believe that? I mean never having to buy one , is it the get what you for pay for type thing?
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I cant answer that. My sender came from VansAuto seller on ebay a few years ago. I think it was 63.00 It works fine with my 67 rally gauge.
 
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