85/86 CFI 5.0 Fuel Sending Unit

[carhopper]

Like many others, my 85 GT AOD/CFI fuel gauge doesn't work. I found this one at Mustangsunlimited.com.
1 F4003R 01 FUEL SENDING UNIT 83/86 3.8/5.0L CFI 54.95

My son and I pulled the tank this morning and discovered that the part above was not right. It is much longer than the stock unit and is designed to work with a mechanical fuel pump. I pulled the existing unit, opened up the switch and sure enough the contacts were worn down to the circuit board. Apparently the 85/86 has a much shorter unit similar to an 87 thunderbird. This is a discontinued item everywhere I looked, but I think I found one. I'll report back when I get the part to see if it's right. This stock unit is supposed to have 8-12 ohms full and 60-86 ohms empty. We'll see.

 

[carhopper]

Nope, the supplier called me today and said the part was not available. Our only hope is to modify something to work in our cars. 85/86 have an unusual 10-70 ohm resistance. The later years starting at 87 have a higher resistance around 260 so it won't work properly. So I took the one I received for the 85 carburetor version, cut it off very carefully with a dremel cut off wheel as not to damage the internals by prying. Cut off the existing upper portion of the plate from my sending unit. Then I used a rivet gun to attach the new switch to the old tube. Then I soldered the wire to the contact. The ony thing left was to bend the float so it travels to the same high and low levels. Here is a picture. I'm likely going to test it tonight, but the resistance is correct.

 

[carhopper]

I finally got around to filling up the car and it goes past full. It was a little over 1/8th of a tank and it took 12.5 gallons. Somebody told me this car has a 13.5 gallon tank, but I read it was 15.

 

[capriman86]

Nobody sells them aftermarket unfortunately, your best bet is to send yours out to these guys, the turn around is VERY quick and about 100-150 bux

S.U.R.&R. is a leading manufacturer of an extensive line of replacement parts used in the Automotive Aftermarket industry.

 

[hill08r1]

carhopper; I am going to attempt the same thing did you have any issues with this mod or was it pretty strait forward? when you say it went past full what does it look like when it is empty? I have an 86 LX 5.0l convertible

 

[FourEyed]

Like Capriman86 said S.U.R.&R. is a leading manufacturer of an extensive line of replacement parts used in the Automotive Aftermarket industry.

They did my 86 sender last year, turned out great. Highly recommended.