fuel sending unit?

[pmotors]

my fuel gauge is pegged at empty, I assumed it was fuel sender.... I just installed a special t auto parts fuel sending unit.. and still
dosnt work?... I did hook up a test light and there is power at the source with the key on... anyone have suggestion?
thanks

[Josh]

Sounds like the gauge or connection at the gauge. Im having a similar issue with my oil sender, Im hoping re-seating the connectors to the binnacle will solve the issue.

[TTait]

When testing a sender - plug it onto the harness and turn it upside down, you should hear the float slide to the "top" and the gauge should read full. Then turn it rightside up again, and hear the float slide down, and the gauge should read empty and the low fuel light should be on.

If all that works, push the gauge down into the tank rather quickly, preferably with 3/4 of a tank of fuel or so with a friend watching the gauge. If the gauge rises slowly to 3/4 (5-15 seconds?) then you should be good to go. If it rises instantly then your sender is letting fuel in and out a bit too easily and quickly and the gauge may bounce around when you stop or make a turn. If it rises to 3/4 but it takes more than a minute - then not enough fuel is getting in and out of your sender. You can then reverse the process and lift the sender out again and see how long it takes the needle to drop to zero. This buffering/dampening is designed in to the design of the unit based on the sizes of the holes at the top and bottom of the sender that let fuel and air go in and out of the bottom and top.

On a Houston unit (sender only - not sender/pump combo) you can adjust this dampening effect a bit by tightening (to make the needle move slower) or loosening (for faster response) one or both of the phillips screws at the bottom - it doesn't take a lot, try 90 degree adjustments and don't over tighten.


If the needle is not moving, unplug the sender and see if the needle moves at all when you do. It should probably at least twitch. Check for good continuity to ground from the sender harness (Black wire?) and check fuse 5.

http://dmctalk.org/showthread.php?40-All-Wiring-Schematics

Then short Green Black to Light Green/Orange and the low fuel light should come on. If all that works then your wiring is probably okay and the sender is bad.

To check the sender you should see resistance change across black and LG/O as you turn the sender right side and up. and you should find continuity between LG/O and GB when the sender is upright, and no continuity if its upside down.

On OEM senders you can check for continuities and voltages at the brass rivets in the top of the sender where the wires are attached.

[pmotors]

when testing a sender - plug it onto the harness and turn it upside down, you should hear the float slide to the "top" and the gauge should read full. Then turn it rightside up again, and hear the float slide down, and the gauge should read empty and the low fuel light should

if all that works, push the gauge down into the tank rather quickly, preferably with 3/4 of a tank of fuel or so with a friend watching the gauge. If the gauge rises slowly to 3/4 (5-15 seconds?) then you should be good to go. If it rises instantly then your sender is letting fuel in and out a bit too easily and quickly and the gauge may bounce around when you stop or make a turn. If it rises to 3/4 but it takes more than a minute - then not enough fuel is getting in and out of your sender. You can then reverse the process and lift the sender out again and see how long it takes the needle to drop to zero. This buffering/dampening is designed in to the design of the unit based on the sizes of the holes at the top and bottom of the sender that let fuel and air go in and out of the bottom and top.

On a houston unit (sender only - not sender/pump combo) you can adjust this dampening effect a bit by tightening (to make the needle move slower) or loosening (for faster response) one or both of the phillips screws at the bottom - it doesn't take a lot, try 90 degree adjustments and don't over tighten.


If the needle is not moving, unplug the sender and see if the needle moves at all when you do. It should probably at least twitch. Check for good continuity to ground from the sender harness (black wire?) and check fuse 5.

http://dmctalk.org/showthread.php?40-all-wiring-schematics

then short green black to light green/orange and the low fuel light should come on. If all that works then your wiring is probably okay and the sender is bad.

To check the sender you should see resistance change across black and lg/o as you turn the sender right side and up. And you should find continuity between lg/o and gb when the sender is upright, and no continuity if its upside down.

On oem senders you can check for continuities and voltages at the brass rivets in the top of the sender where the wires are attached.

tried this already... Still no movement. I will check the ground ( black wiire ) from the harness to gauge.... *is fues #5 the fuel gauge?.. Thank you for the info.

[TTait]

Unfortunately not everything Hervey sells works...

[pmotors]

Ok.. Well... I tested with a test light at the sender harness... I get power, but soon as I plug the sender in I get no power seems it's getting shorted out, if I plug just the positive side without ground connector there is power. As soon as I connect both positive and ground. With test light no power... Hmmm. I'm stumped.

[Ron]

Unplug the connection to the sending unit, key ON. Grounding (Use known good ground. EG jumper to battery negative terminal) the Green/Back wire on the harness side should make the gauge show full. Grounding the LightGreen/Orange wire on the harness side should make the Low Fuel Light come on. If either fails, check for open wire to gauge, connections to gauge/circuit board, gauge. Otherwise suspect the sending unit.

[DMCMW Dave]

Unplug the connection to the sending unit, key ON. Grounding (Use known good ground. EG jumper to battery negative terminal) the Green/Back wire on the harness side should make the gauge show full. Grounding the LightGreen/Orange wire on the harness side should make the Low Fuel Light come on. If either fails, check for open wire to gauge, connections to gauge/circuit board, gauge. Otherwise suspect the sending unit.

Grounding the green/black will make it read empty. "No connection" will make the gauge point straight up. If this is not the case, the gauge or the shunt resistor on the gauge have failed. If the shut resistor has failed, the meter will read about 1/3 when full and empty when empty. If the gauge fails, it will generally read empty all the time but can be anywhere depending on the failure mode.

[Henrik]

Maybe this How-to: Inaccurate fuel gauge readings: How to rule out the actual fuel gauge will help too:
http://dmctalk.org/showthread.php?2291-How-to-Inaccurate-fuel-gauge-readings-How-to-rule-out-the-actual-fuel-gauge&p=30914&viewfull=1#post30914

[Ron]

Grounding the green/black will make it read empty. "No connection" will make the gauge point straight up. If this is not the case, the gauge or the shunt resistor on the gauge have failed. If the shut resistor has failed, the meter will read about 1/3 when full and empty when empty. If the gauge fails, it will generally read empty all the time but can be anywhere depending on the failure mode.



Grounding the green/black will make it read empty. "No connection" will make the gauge point straight up. If this is not the case, the gauge or the shunt resistor on the gauge have failed. If the shut resistor has failed, the meter will read about 1/3 when full and empty when empty. If the gauge fails, it will generally read empty all the time but can be anywhere depending on the failure mode.
Thanks Dave!

..and this:

30990


needs changing to this:

30991

me thinks.