Sending unit? Gauge? Fuel needle confusion...

[ricktheengineer5]

Hey all, got another one for ya.

So in my K5 diesel (M1009 CUCV), the fuel needle very recently started reading inaccurate readings. The current situation is when the tank is full my gauge reads 3/4. It also goes to E properly when empty. Here is a small list of what I have done.

-Cleaned ground by rear drivers wheel. Was already clean, but sanded it down anyways.
-Inspected the push on pink wire on the sender, VERY shiny and clean... Wiped it down anyways.
-Checked resistance of the sender at the sender, reading 87 OHM when "full".
-Checked resistance at the cluster, reading 87 OHM (wiring must be good)
-When keyed up I am getting 12.4V to the gauge
-Resistor on back of gauge is 50 OHM

Does this all sound in spec? I know the sender should be 90 when full, so it seems really close. The needle only started doing this very recently. Any other grounds or things to check? Could it be the gauge itself?

 

[dyeager535]

Hey all, got another one for ya.

So in my K5 diesel (M1009 CUCV), the fuel needle very recently started reading inaccurate readings. The current situation is when the tank is full my gauge reads 3/4. It also goes to E properly when empty. Here is a small list of what I have done.

-Cleaned ground by rear drivers wheel. Was already clean, but sanded it down anyways.
-Inspected the push on pink wire on the sender, VERY shiny and clean... Wiped it down anyways.
-Checked resistance of the sender at the sender, reading 87 OHM when "full".
-Checked resistance at the cluster, reading 87 OHM (wiring must be good)
-When keyed up I am getting 12.4V to the gauge
-Resistor on back of gauge is 50 OHM

Does this all sound in spec? I know the sender should be 90 when full, so it seems really close. The needle only started doing this very recently. Any other grounds or things to check? Could it be the gauge itself?

Quick and easy check is with key in run, disconnect the sending unit wire, wait a minute or so to watch response, then ground the sending wire and watch the response. It should go beyond max empty and full with those tests. If everything up to the gauge tests properly, and it fails the open/short to ground test, the gauge is at fault.