Different fuel gauge problem

[olemanoz]

When I fill up my Bronco the fuel gauge goes to full. The gauge registers correctly until about three-quarters tank then it goes back to full. Stays on full until about three-eights tank then it registers correctly until a little under a quarter when I refill to be safe. Any ideas? Thanks

1987 Bronco XLT

302 c6 trans

b/w 1356 t/c

k&n ghetto filter

bfg 33.12.50 m/t's

 

[WileE7]

When I fill up my Bronco the fuel gauge goes to full. The gauge registers correctly until about three-quarters tank then it goes back to full. Stays on full until about three-eights tank then it registers correctly until a little under a quarter when I refill to be safe. Any ideas? Thanks
1987 Bronco XLT

302 c6 trans

b/w 1356 t/c

k&n ghetto filter

bfg 33.12.50 m/t's

My gauge does the same thing I took it to the Ford dealership and they told me I need to get a new sending unit

 

[miesk5]

My gauge does the same thing I took it to the Ford dealership and they told me I need to get a new sending unit

yo!

Why does my Fuel guage behave erratically?

This is a common problem with older Broncos. It can be caused by several things.

If the guage reads normally for some of its range, but reads full or bounces between full and the real value, the most likely cause is a worn level sender. The fuel level sender is a variable resistor located in the gas tank. A wiper attached to the float rides across the resistor, causing a change in the resistance seen by the dashboard guage. A high resistance (or open circuit) reads as "Full" on Ford gas guages. Over time, the wiper may wear through the resistor, causing dead spots which read as full. The only fix for this problem is to replace the sender. On later model vehicles with in-tank fuel pumps, this can be an expensive proposition. Ford only sells the fuel level sender as part of the fuel pump assembly, which can run well over $150. (see NOTE below)

If the guage behavior doesn't follow any specific pattern, then it is probably related to some other electrical problem. You may want to inspect the wires from the fuel level sender to the guage to see if they are possibly damaged. If other guages are also erratic, there is a good chance that the dashboard voltage regulator is bad.

Bronco FAQ (full version)

Source: by Matt K

NOTE; Ford Bronco - Fuel Level Sending UnitFUEL LEVEL SENDING UNIT -- High Quality, Original Equipment Replacement Part, Direct FitBrand: Motorcraft

Fit: Direct Fit

Price: $46.00

http://www.partstrain.com/templates/pt/ima...aft/sending.jpg

be prepared to replace the sending unit ring that holds the unit in. If it is really rusty I would soak it with PB Blast ( WD-40 ) first and let it sit for a while to make it as easy as possible to remove

 

[olemanoz]

Thanks miesk5 and WileE7 I was afraid it might be the sending unit.

yo!Why does my Fuel guage behave erratically?

This is a common problem with older Broncos. It can be caused by several things.

If the guage reads normally for some of its range, but reads full or bounces between full and the real value, the most likely cause is a worn level sender. The fuel level sender is a variable resistor located in the gas tank. A wiper attached to the float rides across the resistor, causing a change in the resistance seen by the dashboard guage. A high resistance (or open circuit) reads as "Full" on Ford gas guages. Over time, the wiper may wear through the resistor, causing dead spots which read as full. The only fix for this problem is to replace the sender. On later model vehicles with in-tank fuel pumps, this can be an expensive proposition. Ford only sells the fuel level sender as part of the fuel pump assembly, which can run well over $150. (see NOTE below)

If the guage behavior doesn't follow any specific pattern, then it is probably related to some other electrical problem. You may want to inspect the wires from the fuel level sender to the guage to see if they are possibly damaged. If other guages are also erratic, there is a good chance that the dashboard voltage regulator is bad.

Bronco FAQ (full version)

Source: by Matt K

NOTE; Ford Bronco - Fuel Level Sending UnitFUEL LEVEL SENDING UNIT -- High Quality, Original Equipment Replacement Part, Direct FitBrand: Motorcraft

Fit: Direct Fit

Price: $46.00

http://www.partstrain.com/templates/pt/ima...aft/sending.jpg

be prepared to replace the sending unit ring that holds the unit in. If it is really rusty I would soak it with PB Blast ( WD-40 ) first and let it sit for a while to make it as easy as possible to remove

 

[miesk5]

Thanks miesk5 and WileE7 I was afraid it might be the sending unit.

yw, also, some don't drop da tank to replace it or the fuel pump, they cut out a small section of the floor pan; some Links to this are in my site;

Fuel Pump Cut-out Measurements for Fuel Pump/Sender Replacement

also; what it looks like;

Fuel Level Sender, In-Tank Sock filter, etc. Info & pics in a 90 393W Source: by BlueBeast

some tips of removing the lock ring;

Fuel Tank, Pump, & Gauge Troubleshooting, (in-tank pump) in a F 150 (sim to Bronco)Source: by winfordr.com

"...The assembly consists of the fuel pump, float and sending unit, and filter sock..." read more in his article

 

[olemanoz]

Thanks for the links miesk5.

yw, also, some don't drop da tank to replace it or the fuel pump, they cut out a small section of the floor pan; some Links to this are in my site; Fuel Pump Cut-out Measurements for Fuel Pump/Sender Replacement

also; what it looks like;

Fuel Level Sender, In-Tank Sock filter, etc. Info & pics in a 90 393W Source: by BlueBeast

some tips of removing the lock ring;

Fuel Tank, Pump, & Gauge Troubleshooting, (in-tank pump) in a F 150 (sim to Bronco)Source: by winfordr.com

"...The assembly consists of the fuel pump, float and sending unit, and filter sock..." read more in his article

 

[firelt90bronco]

I replaced my sending unit but it still bounces for a while until I hit a huge bump or slam on the brakes. It'll be ok for a while then go crazy again.