Author Topic: Fuel sending unit question  (Read 1158 times)

Offline jason340

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Fuel sending unit question
« on: March 22, 2017 - 01:10:52 PM »
What should the ohms reading at the sending unit be on a full tank of fuel? 70 Challenger.




Offline Bullitt-

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Re: Fuel sending unit question
« Reply #1 on: March 22, 2017 - 10:06:02 PM »
I did a search, 10 ohms full came up several times for fuel sending unit

Ok, I've read all the posts about fuel sender testing. According to the factory specs the sending unit should read about 10 ohms full and about 73 ohms empty. I just got a new sending unit from E-Bay. I set my multi meter to the 200 ohm scale and it reads .6 full and 4.7 empty. If I set the scale to 2000 it reads 2 full and 16 empty. When I hook the unit to the car the gauge in the dash reads full when the sender is full but it reads empty when the sender is at about half.  Now my overhead warning light is always on. I have two relays and they both do the same. I took the relays apart and found nothing bad and continuity is good every where. I don't really no any way to check the relay other than look for obvious burning and checking continuity. I even cleaned the little points in the relay and checked to be sure they were working. Shouldn't all Mopar sending units read the 10 ohms and 73 ohms in order for the dash gauge to read correctly? 
Wade  73 Rallye 340..'77 Millennium Falcon...13 R/T Classic   Huntsville, AL
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Offline Beekeeper

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Re: Fuel sending unit question
« Reply #2 on: March 22, 2017 - 11:23:14 PM »
I agree with 10 ohms. I used a 10 ohm resistor from radio shack with a five volt power source to recalibrate my gauges to to max position (full gas/ max oil pressure/ max temp)


Offline jason340

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Re: Fuel sending unit question
« Reply #3 on: March 23, 2017 - 09:40:15 AM »
Thank you

Offline shawge

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Re: Fuel sending unit question
« Reply #4 on: March 23, 2017 - 11:24:17 AM »
Miller calibration tool lists these ohm ranges
Low = 73.7 Ohms
Half = 23.0 Ohms
Full = 10.2 Ohms
- Jerry