ohm sweet ohm / 69Maro fuel sending unit - Team Camaro Tech
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post #1 of 9 (permalink) Old Dec 27th, 06, 02:35 PM Thread Starter
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chris
 
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ohm sweet ohm / 69Maro fuel sending unit

I am trying to read the ohms on a brand new fuel sending unit for my 69 camaro (350). The problem is I only get 54 ohms at "full tank" on it. (And 0 ohms at empty tank)
I thought that the factory sending units were supposed to be 90 ohm at full and 0 at empty???

I am checking this with a digital ohm meter connected to the lug on the top of the unit and to the body of the unit.

This is the second time I have seen this and am wondering if it's just another bad (brand new)unit???
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post #2 of 9 (permalink) Old Dec 27th, 06, 03:19 PM
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Re: ohm sweet ohm / 69Maro fuel sending unit

Yes, 90 ohms is correct. You should ground the unit then try again to see what it shows for ohms.

Kev
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post #3 of 9 (permalink) Old Dec 27th, 06, 03:23 PM
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Re: ohm sweet ohm / 69Maro fuel sending unit

you do have the circuit disconnected, right? You pulled the connector in the trunk or at the sender?





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post #4 of 9 (permalink) Old Dec 27th, 06, 05:39 PM
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Re: ohm sweet ohm / 69Maro fuel sending unit

Jim,
I read it as he has the unit in hand and not in the tank. That is why I said to be sure and ground the unit. Could be wrong..

Kev
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post #5 of 9 (permalink) Old Dec 27th, 06, 08:12 PM Thread Starter
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Re: ohm sweet ohm / 69Maro fuel sending unit

Guys,

I am checking this brand new, never installed unit, as I hold it in my hand not in the car.

The deal is that this is the second new one to read exactly 54ohms at full tank. The first one I sent back because I thought it was faulty.
I should be reading 90ohms right?
Has anyone else thought to check the ohms on a new sender before installing it??
Only other option, I am thinking, I need to try another fluke meter for a second opinion.

Thanks for the input and I wish I could have posted sooner!
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post #6 of 9 (permalink) Old Dec 28th, 06, 07:00 PM
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Re: ohm sweet ohm / 69Maro fuel sending unit

chrisp1,

You are checking the resistance correctly. By connecting one of the voltmeter leads to the body, you are effectively "grounding" it. Sounds like a bad one to me too.

Larry
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post #7 of 9 (permalink) Old Dec 30th, 06, 07:32 AM Thread Starter
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chris
 
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Re: ohm sweet ohm / 69Maro fuel sending unit

This seems crazy but....

I tested the sending unit with a different digital multimeter (Fluke) and still 54 ohms.

Then tested it with an analog meter (Sperry)and now 90 ohms

ChrisP
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post #8 of 9 (permalink) Old Dec 30th, 06, 08:57 AM
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Re: ohm sweet ohm / 69Maro fuel sending unit

I wonder if you have a calibration problem with the Fluke. You could go to Radio Shack and get a few resistors to check the meters. Right now, you have a 50-50 chance of the sender being bad.

Can you temporarily connect the sender to the gauge, power up the system, and see how the gauge reacts? I think that would be the ultimate way to test it.

Larry
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post #9 of 9 (permalink) Old Dec 30th, 06, 03:23 PM Thread Starter
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Re: ohm sweet ohm / 69Maro fuel sending unit

Quote:
Originally Posted by 69-er View Post
I wonder if you have a calibration problem with the Fluke. You could go to Radio Shack and get a few resistors to check the meters. Right now, you have a 50-50 chance of the sender being bad.

Can you temporarily connect the sender to the gauge, power up the system, and see how the gauge reacts? I think that would be the ultimate way to test it.

Larry
Larry,
I will connect to the gauge as a sure fire way of knowing if the sender is bad before I install it in the tank, but I just think its kinda strange that two digital Flukes are reading the exact same(54ohms), and an analog meter reading perfect 90ohms.

Good idea on checking with a resistor, I'll try that. But, the digital meters should not need calibration as one is new and the other is just a few months old. I'll check anyway.

ChrisP
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