# Determining Fuel-Guage Ohms Requirements from Sending Unit

**URL:** <https://community.cartalk.com/t/determining-fuel-guage-ohms-requirements-from-sending-unit/11776>\
**Category:** Maintenance/Repairs\
**Created:** [March 14, 2008, 12:25am UTC](https://community.cartalk.com/t/determining-fuel-guage-ohms-requirements-from-sending-unit/11776 "2008-03-14T00:25:34Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![ChevyC60](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/chevyc60/32/310_2.png) [@ChevyC60](https://community.cartalk.com/u/ChevyC60)\
**Post date:** [March 14, 2008, 12:25am UTC](https://community.cartalk.com/t/determining-fuel-guage-ohms-requirements-from-sending-unit/11776/1 "2008-03-14T00:25:34Z")

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I mistakenly upgraded my fuel tank capacity to one incompatible with my guages. Furthermore, Im stubborn and dont want tacky OEM guages hanging above or below my dash. I intend on using a generic vehicles instrument cluster of the same year (but different model that went with a larger tank). The sending unit is off a 95 GM 2-ton (model unknown) I dont know if this is all TMI, but I just need to how to determine my sending units requirements utilizing say, an ohmmeter. The sending unit has FOUR leads. How is it performed?

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**Author:** ![the\_same\_mountainbike](https://avatars.discourse-cdn.com/v4/letter/t/c89c15/32.png) [@the\_same\_mountainbike](https://community.cartalk.com/u/the_same_mountainbike)\
**Post date:** [March 14, 2008, 5:38pm UTC](https://community.cartalk.com/t/determining-fuel-guage-ohms-requirements-from-sending-unit/11776/2 "2008-03-14T17:38:39Z")

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I don’t know what to make of this post.

Why not use the gages off of the 95 GM 2-ton? Or just hook it up and see how it reads?

Oh, and OEM means Original Equipment Manufacturer. The tacky ones hanging down from the dash are aftermarket accessory gages.

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**Author:** ![willey](https://avatars.discourse-cdn.com/v4/letter/w/a9adbd/32.png) [@willey](https://community.cartalk.com/u/willey)\
**Post date:** [March 14, 2008, 8:22pm UTC](https://community.cartalk.com/t/determining-fuel-guage-ohms-requirements-from-sending-unit/11776/3 "2008-03-14T20:22:12Z")

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Yeah, I don’t get it either. Did you install a different sending unit? The original fuel pump/sending unit will mount in a different tank with no problems.

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**Author:** ![ChevyC60](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/chevyc60/32/310_2.png) [@ChevyC60](https://community.cartalk.com/u/ChevyC60)\
**Post date:** [March 15, 2008, 7:55pm UTC](https://community.cartalk.com/t/determining-fuel-guage-ohms-requirements-from-sending-unit/11776/4 "2008-03-15T19:55:14Z")

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I DONT KNOW THE EXACT MODEL THE TANK CAME OFF OF. Not knowing the precise vehicle model could be catastrophic. Supposing I even found such rare instrument panel via salvage, which wires go to what leads if the plugs look different? Suppose I accidentally sent voltage down the wrong lead?..KABOOM!

This is why I want to test it first, before a “wet” run, and also determine ohms/resistance requirements in the event it differs from a generic 95 model GM.

Attached is a photo of the sending unit leads if this helps any.

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**Author:** ![willey](https://avatars.discourse-cdn.com/v4/letter/w/a9adbd/32.png) [@willey](https://community.cartalk.com/u/willey)\
**Post date:** [March 15, 2008, 9:32pm UTC](https://community.cartalk.com/t/determining-fuel-guage-ohms-requirements-from-sending-unit/11776/5 "2008-03-15T21:32:40Z")

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Can’t you take the old sending unit and install it in the new tank?

The other thing is that the sending unit is the ground for the gauge, power goes through the gauge first then to the sending unit.