gas gauge ohm reading on 78

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joeshmo

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hey guys i have a 78 bronco with the 351m and i wondered if anyone knew the ohm reading for the gas gauge that i can use to get a universal sending unit. can anyone help me please????

 

miesk5

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yo,

Our Sponsor here has them for both tank sizes; Jeff's Bronco Graveyard @ http://broncograveyard.com/bronco/c-86-bronco-fuel-systems.html

78-86 has the old sender...75 - 10 ohm (empty-full)

This is by by Auto Meter @ http://www.autometer.com/tech_faq_answer.aspx?sid=1&qid=56

"...The Ford Fuel Level sensor with a 73-10ohm range operates with the following ohm ranges for Full, Half, Empty, and Below Empty:

Full: 10ohms

Half Tank: 25ohms

Empty: 50ohms

Pointer Width Below E: 73ohms

If you have replaced the original equipment Ford sending unit in your vehicle with an aftermarket sending unit, you may notice that the gauge will match the sending unit at the Full and Empty portions of the scale, but that the readings in between will not match up. The reason for this is that some aftermarket senders operating with the 73-10ohm range now utilize a linear movement instead of the original non-linear scale. The comparative ohm reading difference for Full, Half, and Empty have been supplied below for your reference.

Full: 10ohms

Half Tank: 41ohms

Empty: 73ohms

As you can see these numbers differ radically from those of the factory Ford sending units and have a drastic effect upon the gauge readings.

In the event that you have this situation, we recommend one of two options. The first would be to seek an original equipment fuel level sending unit from Ford directly for your vehicle..." read more

 

Sven

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yo,

Our Sponsor here has them for both tank sizes; Jeff's Bronco Graveyard @ http://broncograveyard.com/bronco/c-86-bronco-fuel-systems.html

78-86 has the old sender...75 - 10 ohm (empty-full)

This is by by Auto Meter @ http://www.autometer.com/tech_faq_answer.aspx?sid=1&qid=56

"...The Ford Fuel Level sensor with a 73-10ohm range operates with the following ohm ranges for Full, Half, Empty, and Below Empty:

Full: 10ohms

Half Tank: 25ohms

Empty: 50ohms

Pointer Width Below E: 73ohms

If you have replaced the original equipment Ford sending unit in your vehicle with an aftermarket sending unit, you may notice that the gauge will match the sending unit at the Full and Empty portions of the scale, but that the readings in between will not match up. The reason for this is that some aftermarket senders operating with the 73-10ohm range now utilize a linear movement instead of the original non-linear scale. The comparative ohm reading difference for Full, Half, and Empty have been supplied below for your reference.

Full: 10ohms

Half Tank: 41ohms

Empty: 73ohms

As you can see these numbers differ radically from those of the factory Ford sending units and have a drastic effect upon the gauge readings.

In the event that you have this situation, we recommend one of two options. The first would be to seek an original equipment fuel level sending unit from Ford directly for your vehicle..." read more

What is the correct Half tank reading 25 Ohm? or 41?
I have a NWMP 45 gallon tank and need a new sending unit where can I get one? I hope someone can help Thanks Sven
 

johnnyreb

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yo,

Our Sponsor here has them for both tank sizes; Jeff's Bronco Graveyard @ http://broncograveyard.com/bronco/c-86-bronco-fuel-systems.html

78-86 has the old sender...75 - 10 ohm (empty-full)

This is by by Auto Meter @ http://www.autometer.com/tech_faq_answer.aspx?sid=1&qid=56

"...The Ford Fuel Level sensor with a 73-10ohm range operates with the following ohm ranges for Full, Half, Empty, and Below Empty:

Full: 10ohms

Half Tank: 25ohms

Empty: 50ohms

Pointer Width Below E: 73ohms

If you have replaced the original equipment Ford sending unit in your vehicle with an aftermarket sending unit, you may notice that the gauge will match the sending unit at the Full and Empty portions of the scale, but that the readings in between will not match up. The reason for this is that some aftermarket senders operating with the 73-10ohm range now utilize a linear movement instead of the original non-linear scale. The comparative ohm reading difference for Full, Half, and Empty have been supplied below for your reference.

Full: 10ohms

Half Tank: 41ohms

Empty: 73ohms

As you can see these numbers differ radically from those of the factory Ford sending units and have a drastic effect upon the gauge readings.

In the event that you have this situation, we recommend one of two options. The first would be to seek an original equipment fuel level sending unit from Ford directly for your vehicle..." read more
Mike,I replaced the original tank (it had rusted holes in it) to a 33 gallon tank. I got a 33 gallon sending untit from JBG,but its not giving a correct reading. Do you think Ford would have a sending unit for a 78 with a 33 gallon tank and did the 78 Bronco have the 33 gallon tank in 78? Thanks
 

miesk5

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Yo Johnny,
According to 78 Bronco Dealer Brochure @ http://www.supermotors.net/clubs/superford/registry/1964/33111-2

78s were built with a standard tank of 25 gallons and an optional tank of 32 gallons which our 78 351M had when we purchased it new. 78bb_bkcvr.jpg
79s were also built with 25 gallon and optional 32 gallon tanks according to 1979 Bronco Dealer Brochure @ https://www.xr793.com/wp-content/uploads/2020/07/1979-Ford-Bronco.pdf

Broncograveyard.com offers, "We offer a video to help decipher what tank is right for you." @ https://shop.broncograveyard.com/FUEL-SYSTEMS-BRONCO/departments/1512/

Sending units available from them are listed today at 25.5 (OUT OF STOCK) & 33 gallon.

How far off do you believe the gauge is off?


1979-bronco-f100-through-f350_page_30 (1).jpg1979-bronco-f100-through-f350_page_31 (1).jpg

From 1979 Bronco/F Series Electrical & Vacuum Troubleshooting Manual by Ford

Tech Tip Guide, General; "...Many times, the Ford fuel pump hanger/sender assemblies are frequently found with extensive corrosion on the cover and on the metal tubes. Over time, the terminals can loosen and cause intermittent loss of continuity. Erratic reading of the fuel sender level is one of the other problems that could occur..." by spectrapremium.com

Testing in an 78-86; "...Ground the Y/Wh wire at the fuel tank, turn the key to RUN, and observe the gauge. If it pegs FULL, the sender is bad inside the tank. If it stays at EMPTY, it's an electrical fault, probably in the cluster, or its connector..." by Steve

Testing; "...floats either way; There is a brass float attached to the sending unit, and eventually they can develop a pin hole leak.."
 
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johnnyreb

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Its WAY OFF. The tank was full and the gauge barely moved. I,ll re-check all the wires and grounds .Hopefully today. Thanks for the information Mike--Independence CV-62
 

miesk5

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Johnny,
I tested many electrical systems on Indy in mid to late 80s during it's modernization in Philly!

From a fading memory, I flew over Indy around Christmas time 65 while it was in Norfolk.

Thanks for your Service Johnny!
 

johnnyreb

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Johnny,
I tested many electrical systems on Indy in mid to late 80s during it's modernization in Philly!

From a fading memory, I flew over Indy around Christmas time 65 while it was in Norfolk.

Thanks for your Service Johnny!
I got out of the army in 72. I couldn,t find a job and everyone thought we were either crazy or a ******. In 76--I joined the navy (Feb 76) I was on the Indy from Feb 76-Feb 77. Then I went to shore duty at *** AND NAS Norfolk.
 

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