While going home from work yesterday, my fuel gauge started
reading over the "full" mark. Does anybody have a schematic
for the fuel gauge & sending unit??? All other gauges are reading
correctly.

This is on a 1999 2WD, std. cab 3.0L FFV.

Thanks!!!!

 

Ford gas gauges suck, unfortionatly to say, but ive not been in many Ford vehicles (trucks atleast) that havent had trouble with the gas gauge, with the exception of a few of the brand new ones, or the lightnings. I dunno, yours is fairly new, i would see if its too late to take it up with the warranty.

 

Thanks Traxxis, unfortunately, it has 73K miles on it, so it's out
of warranty....

 

I have had the same problem , is there any after market gauge i can buy? Because when i get close to empty i have the same problem, I don't know when i'm really empty. (PLus i have to fuel waring light. So it blows, any info would be great. Thanks

--Matt

 

Okay, for Zoopers' 93, i found a set..... https://www.ford-trucks.com/forums/n...hreadid=120652

And Bob, for your '99.... https://www.ford-trucks.com/forums/n...hreadid=120652

Actually, they may be the same for both, i dunno, i did separate searches for each. You know, i just really had to learn to "feel" my truck, unfortionatly for Bob, man... your truck is new, and that's a bunch of crap, and i wish i knew what to tell you man, i mean, personally, i would try to write Ford a piece of my mind and see if they would take care of you. Zooper, man, we're just screwed unless we wanna spend some good money for new gauges. Good luck guys, hope this helps. Let me know what you decide to do.

 

Thanks Traxxis for the research you have done into my fuel
gauge problem!!

I'm also fortunate to have friends like Rockledge, and Ken00, who
have sent me instrument panel schematics. After reviewing the
schematics, if the resistance of the sending unit goes too high
(in the case of an open circuit), this will make the fuel gauge
read excessively HIGH. The resistance of the sending unit gets
lower as the fuel level gets lower.

As an update, my wife and I made a trip to W.Va. today, and the
fuel gauge started working when the tank was about half full.
This is telling me that the problem is the sending unit "opening
up" when the tank is full.....

Is the fuel level sending unit a "dealer only" item, and are there
any suggestions for dropping the tank???

Many thanks!!!!!!!!!!!!!!! Bob

 

Sounds to me like you have the wrong Motorcraft plug Bob.

 

Mine did the same thing. If you reach up and unpplug the harness on the top of the tank, locate the yellow/white wire and short it to ground, turn your key off and back on, it should read empty. take it loose and turn the key off/on and it should go back full (or above full). if it does, the problem is in the feul sender. If not, chase it to the guage. This isolates it to the tak or guage.

Yellow/White- signal wire.

The float is just a pot that references to ground so don't worry about blowing anything if you short it to gnd.
The "official test procedure says to use a special test box, shorting the sig wire to gnd or to 12v will do the same thingh. Or if you are so inclined, make a tester out of a 300ohm pot for $2 at radio shack.
Mine was the sender, by the way. Found a used one with 2k miles from LKQ on the web for $100.00

Autozone wants $330.00 (pump included).


Hope this helps. I have the factory disk that shows this info for trouble shooting.
Good luck

Pinpoint Tests

PINPOINT TEST A: FUEL LEVEL READS INACCURATELY

² A1: VERIFY POWER AT FUSE 11 -- LOAD SIDE
² A2: VERIFY POWER AT FUSE 11 -- FEED SIDE
² A3: VERIFY POWER AT CLUSTER CIRCUIT 640 (R/Y)
² A4: VERIFY GROUND CIRCUIT 570 (BK/W)
² A5: CHECK FUEL GAUGE (EMPTY)
² A6: RECHECK FUEL GAUGE (EMPTY)
² A7: CHECK PRINTED CIRCUIT BOARD
² A8: CHECK INSTRUMENT CLUSTER GAUGE AMPLIFIER (EMPTY)
² A9: CHECK FUEL GAUGE SENDING UNIT WIRE
² A10: CHECK FUEL SENDING UNIT GROUND
A10 CHECK FUEL SENDING UNIT GROUND


l Key OFF.

l Measure the resistance of Circuit 651 (BK/Y) (Ranger and Explorer) or "BK/W" (Aerostar) wire at the fuel gauge sending unit connector to ground at battery.

l Is the resistance less than 1 ohm?

Yes
GO to «A11».

No
SERVICE Circuit 651 (BK/Y) (Ranger and Explorer) or "BK/W" (Aerostar) wire from the fuel gauge sending unit to ground.
² A11: CHECK FUEL GAUGE (FULL)
Pinpoint Tests

PINPOINT TEST A: FUEL LEVEL READS INACCURATELY


A11 CHECK FUEL GAUGE (FULL)


l Key OFF.

l Disconnect the fuel gauge sending unit.

l Connect one lead of the Rotunda Instrument Gauge System Tester 021-00055 or equivalent to Circuit 29 (Y/W) at the fuel gauge sending unit connector and the other lead to ground.

l Set the tester to 145 ohms.

l Key ON.

l Wait one minute.

l Read the fuel gauge.

l Does the fuel gauge read F (full)?

Yes
GO to «A13».

No
GO to «A12».


² A12: CHECK INSTRUMENT CLUSTER GAUGE AMPLIFIER (FULL)
Pinpoint Tests

PINPOINT TEST A: FUEL LEVEL READS INACCURATELY


A12 CHECK INSTRUMENT CLUSTER GAUGE AMPLIFIER (FULL)


l Turn the key to OFF position. Remove the instrument cluster. Inspect the instrument cluster printed circuit. Remove the instrument cluster gauge amplifier. Connect the jumper wire from the Rotunda Instrument Gauge System Tester 021-00055 or equivalent directly to the fuel gauge "SIG" terminal.

l Install the instrument cluster.

l Turn the key to the ON position.

l Read the fuel gauge.

l Does the fuel gauge read F (full)?

Yes

REPLACE the « Instrument Cluster Gauge Amplifier» as described in Removal and Installation in this section. GO to «A5».

No
REPLACE the fuel gauge as described in «Removal and Installation» in this section. RETURN to«A5».

 

There is some very good info in this thread to troubleshoot my problem.

Is there any way to gain access to the fuel sender without dismantling the truck or removing the fuel tank? Can access be attained from the cab?

Thanks in advance.

Rod

 

Reps to you jbabbler. That is a lot of useful information. Thank you.