Re: Fuel Senders

[jlandry@domain.elided (John A. Landry)]

With the crack of the whip, "Allan Weidenheimer" <allanw@domain.elided>
moaned with pleasure and gasped:

>>John Landry wrote:
>>The closest is the Chrysler type.  My bench testing of the IH gauges would
>>suggest 10 Ohms will get you a full or near full reading and 78 Ohms will
>>net a reading of dead empty.
>
>I believe John is correct, but would like to see if we can get this cleared
>up so I can dump something into the FAQ.  My IH service manual 
>(CTS-2303, for T-all/Pickups) identifies the sender as a
>0 to 90 Ohm unit, with a resistance of 88-92 ohms in the 'FULL'
>position, and having less than 1 ohm in the 'EMPTY' position.

Boy... I don't know what's going on in your reference material Allan, but I
can swear to you that my in every single IH gauge I've gotten my hands on...
both out of my 1976 Traveler and various Scouts or pickups from wrecking
yards... my bench testing shows that near zero (0) Ohms of "sending unit"
resistance results in full deflection of the gauge.  Full deflection means
FULL, HOT, or HIGH PRESSURE, depending on which gauge and how it's marked.
All of the gauges operate the same, only the index markings are different.

High resistance of the sending unit in excess of about 80 Ohms results in
little or no movement in the IH gauge.  I made a little 14 volt DC power
supply and variable resistor to test this out.  I verified the resistance
figures with a digital multimeter.

To the best of my knowledge, this is exactly the way the Chrysler type fuel
level sending unit works... full tank = 0 Ohms, empty tank = 90 Ohms.

Maybe that's a misprint in your shop manual???

Take care,

John

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