72 cuda fuel gauge issue
08-28-2013, 09:19 AM
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72 cuda fuel gauge issue
Any ideal why my fuel gauge isnt reading right? it has a new sending unit an tank but it only will read up to 1/8 a tank when full. i took sending unit out thinking float was cracked and it wasnt ,tested it with multi meter and all was fine. HELP
08-30-2013, 08:48 AM
#5
It seems to be a well known internet "fact" that repop senders aren't quite right, but FIRST you need to see if the gauge is actually correct.
First, if you are still using an old original instrument voltage limiter, I'd just replace it "because." RTE sells replacement solid state ones, or if you Google around you can actually build them
Next get some resistors from Radio Shack and test the gauge for accuracy, OR diddle with fuel level to get a specific resistance.
You want about 10 - 15 ohms for full, 23 -- 25 ohms for 1/2, and 70 -- 75 ohms at empty
For example you can buy a pack of four 100 ohm, 1/2 watt resistors and wire all four in parallel. This makes a 25 ohm resistor that should give you 1/2 scale after about a minute with power on. Or, you can siphon/ add gas until you get to that point, and or the other values to check full or empty
You can also use your resistors to check the temp gauge, as well as oil if equipped. All the gauges use the same scale movement.
Once you know the gauge is correct, it's a matter of bending the arm some to get empty to read right. Some guys have added series resistance to get "full" to read right.
I've seen no good writeup that shows a sure fire cure for the problems with modern senders.
First, if you are still using an old original instrument voltage limiter, I'd just replace it "because." RTE sells replacement solid state ones, or if you Google around you can actually build them
Next get some resistors from Radio Shack and test the gauge for accuracy, OR diddle with fuel level to get a specific resistance.
You want about 10 - 15 ohms for full, 23 -- 25 ohms for 1/2, and 70 -- 75 ohms at empty
For example you can buy a pack of four 100 ohm, 1/2 watt resistors and wire all four in parallel. This makes a 25 ohm resistor that should give you 1/2 scale after about a minute with power on. Or, you can siphon/ add gas until you get to that point, and or the other values to check full or empty
You can also use your resistors to check the temp gauge, as well as oil if equipped. All the gauges use the same scale movement.
Once you know the gauge is correct, it's a matter of bending the arm some to get empty to read right. Some guys have added series resistance to get "full" to read right.
I've seen no good writeup that shows a sure fire cure for the problems with modern senders.
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RacerHog (08-30-2013)
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