Recently my fuel gauge started acting up and eventually stopped working all together. Towards the end it would bounce back and forth between half a tank and full non stop. I picked up a nos fuel gauge and the needle stays steady at 3/4. Problem is I know that is way off. There is only about a 1/4 in the tank. I think I need to replace the fuel sending unit. Any of you had any issues with the new repro ones I see on Ebay specifically for these truck years? The description says they have the correct ohms. Thanks in advance for any help I can get.

 

I cant say anything about the ones on ebay, but the LMC unit is way off.

Check out this thread for more info:

https://www.ford-trucks.com/forums/1...nit-grief.html

 

Bolted to the back of the instrument cluster is the ICVR - Instrument Cluster Voltage Regulator.

When it begins to fail, the fuel and temp gauges begin to do "the hula" swinging wildly back and forth on their own.

Fuel sending unit float is made from two pieces of copper soldered together. Solder breaks down, gas seeps in, float settles towards the bottom of the tank.

Float is the same: 1957/79 Passenger Cars/Trucks, 1961/79 Econolines and 1966/79 Bronco's. It's available from Ford, but...

Carpenter sells a one piece brass float that will never leak for about 5 bucks.

 

Wondering if a bad float partially full of gas, would start flopping and result in those indications. Once it sinks for good it's going to show empty.

The CVR gets replaced un-necessarily sometimes. Maybe most of the time? They are pricey little buggers too - $25-45 depending on who is stealing yer money. You can roll yer own with Radio Shack parts for about 5 - but make sure it's at fault first.

Swapped the repro sending unit 5 years old into the new tank last week and it had held up pretty good still shiny and clean. But like its predecessor, would only show 3/4 tank indicated on the gauge. Got it from Mac's, but I bet the LMC is the same one?

Once I looked at it (again) the fix was easy as pie. The repro version can be calibrated w/ set screw on float arm shaft. If your fuel gauge pegs full indicated when grounded after a minute then everything should be OK, what you want to do is adjust the float arm for a full tank indication (with a full tank) + a little over on the gauge and see how that works.

Not sure if the original type sending unit is adjustable.

 

I replaced the icvr last month. That was my first guess when it acted up. Ill check the float on the sending unit and the arm. I Replaced The Float Last year and I know the ground is good too. I'm hoping it's a small issue, I've read several stories on here about not getting these gauges to read right.

 

B8C-9275-B (replaced B7C-9275-B) .. Fuel Tank Sending Unit-Use with In-Cab Fuel Tank / Obsolete

Applications: 1957 F100/1100 / 1958/60 F100/950.

WESLEY OBSOLETE PARTS in Liberty KY has 2 = 606-787-5293.

DON SANDERSON FORD in Glendale AZ has 5 = 623-842-8643.

GREEN SALES CO. in Cincinnati OH has 6 = 800-543-4959.

CARPENTER NOS OBSOLETE PARTS in Concord NC has 141 = 800-476-9653.

 

Where are you guys buying an ICVR? My temp gauge has never worked, and my fuel gauge recently quit working in a similar fashion as described above (acting all wonky for a while before giving up entirely). If it's a cheap part I wouldn't mind throwing it in and seeing if it fixes both.

If it was the ICVR, would it make sense that my temp gauge wouldn't work for over a year before the gas gauge went out, or would they be right around the same time?

Disclaimer: I haven't looked into why the temperature gauge doesn't work, so it could just be unplugged or something stupid.

 

The repro fuel sending units at least have a set screw attaching the float arm to the business end of the unit. If the gauge reads low on a full tank then kinda eyeball it and move the whole float arm on the shaft about 45 or 90 deg lower, (do not bend the arm, reset the calibration point) if it reads high reset the float arm the other direction in the same way.

 

The owners manual shows how to test these and most other parts! Helps to do it right the first time instead of throwing money in the dark.
Sorry just had to rant!


I ment SHOP manual.

 

B9MZ-10804-C .. ICVR ~ Instrument Cluster Voltage Regulator (Motorcraft GR-508) / Obsolete ~ Available NOS, from repro parts sellers & auto parts stores.

Applications: 1957/66 F100/1100 / 1960/65 Falcon/Comet / 1960/66 Galaxie/Thunderbird / 1962/65 Fairlane / 1965/66 Mustang / 1966/77 Bronco.
$25-45 is cheap, when one considers that B9MZ-10804-C = Last MSRP: $97.05 - Dealer net cost: $64.70.