Fuel sending unit now available for 83-88 buttstuffog guage birds & cougs

Topic: Fuel sending unit now available for 83-88 buttstuffog guage birds & cougs (Read 2978 times) previous topic - next topic

Fuel sending unit now available for 83-88 buttstuffog guage birds & cougs

January 01, 2017, 05:22:59 PM

Summit Racing Fuel sending unit modification Pn 290260

0 ohms empty & 90 ohms full
Modification, make the sending unit read the opposite.
Observation: After this mod, the max resistance is now 84 ohms (empty tank)
Vehicle application: 1983-88 ford thunderbird or mercury cougar with buttstuffog fuel gauge.

Notes: On the Summit unit there are 25 individual resistive PCB fingers each being about 3.6 ohms. In the shipped condition this unit reads 89.9ohms max. When this mod is done, you will end up with 85 ohms max reading because of how the last resistive leg is bonded. The Summit unit is very linear with respect to resistive sweep while the ford units are not incremented so simply. On the Fomoco units the resistivity in the upper and lower 25% range are higher resistances than in the middle.

Many ford enthusiasts can recall their fuel gauge dropping from F to ¾ very slowly , then quickly to just a hair below ½ tank, then the fuel needle would drop slowly again down to E. With this summit option I believe my needle will drop equally across the full sweep of my fuel gauge making it feel more informative.

Compare your fuel sending unit to the Summit 290260 sending unit.
Left unit is FoMoCo and the right is the Summit unit needing modification to match Ford oem specs.

Fuel sending unit now available for 83-88 buttstuffog guage birds & cougs

Reply #1 – January 01, 2017, 05:31:33 PM

Step 1

By hand, spin a drill bit inside the rivet of the summit unit to allow it to be opened.

Fuel sending unit now available for 83-88 buttstuffog guage birds & cougs

Reply #2 – January 01, 2017, 05:36:02 PM

Step 2

Disassemble the Summit unit and track which order your hardware goes. The intent from the supplier is to insure you have a completely insulated +12vdc power stud for wiring into your car.
Note: FoMoCo used a collector ring contact system to achieve a ground potential. In the summit unit this feature is replaced with a separate ceramic PCB ground path. Notice on the ford unit there is one contact rubbing one arched set of individual resistance PCB tabs. On the summit unit you have the same resistive arch and also a separate contact to rub against a constant ground potential.

Fuel sending unit now available for 83-88 buttstuffog guage birds & cougs

Reply #3 – January 01, 2017, 05:38:58 PM

Step 3

DE solder the supplied metal power strap from the PCB and keep the ring lug side of it only. Install a power and ground wire as shown below. Once you do this then reassemble and test your resistance. It will now provide an opposite resistance range. Re-assemble and adjust float rod to suit your tank depth.

You will notice that i soldered the black ground wire. In stock form, this is a loose connection stright out of the box.
It is a design error and the ground lug is supposed to be sandiched between the cover and baking plate and the rivit you drilled out is 'supposed' to keep it snug.

FAIL!

I fixed that.

Fuel sending unit now available for 83-88 buttstuffog guage birds & cougs

Reply #4 – January 01, 2017, 10:10:26 PM

Nice write up. I'm going to have to do that to my black birds unit.

Fuel sending unit now available for 83-88 buttstuffog guage birds & cougs

Reply #5 – January 02, 2017, 02:32:56 PM

where in the heck did all those stars come from on the title? i didnt know we could do that here, rate threads and such

Fuel sending unit now available for 83-88 buttstuffog guage birds & cougs

Reply #6 – January 03, 2017, 11:23:27 AM

I will add something later if i find out it is needed.
when my fuel float is touching the top of the tank in the "full" simulated position, i need to insure that there is resistance of a few ohms like 8 or so.

i will need to achieve two things
1- make sure the float arm reads and touches the top of the tank with 8ohm
2- make sure the float arm reads high resistance and touches the bottom of the tank.

Fuel sending unit now available for 83-88 buttstuffog guage birds & cougs

Reply #7 – January 03, 2017, 11:24:33 AM

as an fyi,, the two contacts are actualy one peice of metal shaped like a "U". incase someone was scratching thier head.

Fuel sending unit now available for 83-88 buttstuffog guage birds & cougs

Reply #8 – January 06, 2017, 01:29:07 PM

Revised step by step for original posting of this thread.

Fuel sending unit now available for 83-88 buttstuffog guage birds & cougs

Reply #9 – January 08, 2017, 08:54:25 AM

see updates,
relocated ground wire to a new stud which will tie to my auxillary ground for the tank itself.
see float rod calibrated to 85ohms empty & 10 ohms full

Fuel sending unit now available for 83-88 buttstuffog guage birds & cougs

Reply #10 – January 08, 2017, 08:57:32 AM

in the tank now,, ready for service

in order to use the stock locking ring you have to bend the tank locking tabs up a tiny bit.
The reason is the round metal top is not sheet metal but approx 3/16'' ,, hence you bend the tank locking tabs up.

Fuel sending unit now available for 83-88 buttstuffog guage birds & cougs

Reply #11 – January 27, 2017, 03:02:08 PM

Very nice...

Fuel sending unit now available for 83-88 buttstuffog guage birds & cougs

Reply #12 – January 30, 2017, 09:20:27 PM

Hello,

I spoke with member Eric and he recommended I buy a new pump/sending unit. I can't figure out how to start a seperate post on my iPad so I apologize for piggybacking off of your post but I feel that maybe you can help. Has anyone ever experienced a situation where the digital gas gauge reads "U"? It's very strange - Any advice would be helpful. Thankyou so much! 🙂

Cody

Fuel sending unit now available for 83-88 buttstuffog guage birds & cougs

Reply #13 – February 03, 2017, 10:04:42 AM

i see you got your own thread going,,, replied to you.