Fuel gauges reading off-scale high and off-scale low

[Tbob17]

I have 2 Mep-803a generators- one came with the fuel guage reading off-scale low and the other reading off-scale high. Do both readings indicate a fuel gauge failure, or not necessarily? It doesn’t matter whether power is applied to the unit or not, and even after disconnecting all leads and reconnecting, the reading remains the same. I also swapped the gauges between the other units and they indicate the same way-The gauges never moves. Thank you.

 

[Guyfang]

Have you looked at the schematics, to insure that someone did not hook them up right, and you, hooking them up without checking the schematics, repeat the failure? This happens often.

 

[Tbob17]

Have you looked at the schematics, to insure that someone did not hook them up right, and you, hooking them up without checking the schematics, repeat the failure? This happens often.

I had found that it was hooked up incorrectly and they had 24 V to the “”sender” post on one of them. So, I wondered if that may have cooked the gauge. I corrected the wiring, but still got the same dead reading on the fuel gauge. On the other generator, the leads were hooked up correctly.

 

[Light in the Dark]

The fuel gauges are one of the most common gauge failures on these machines. If you want OEM replacements: https://steelsoldiers.com/threads/m...3-beede-945331-6625-01-366-0193-70-ea.199406/

If they are wired right, all the way right unmoving is normally a dead gauge. If all the way left... check the wiring on the sender. If thats correct and its still not reading when powered... its also dead.

 

[Guyfang]

This procedure is found in TM 9-6115-642-24. Its always a good Idea to download the TM's and read the troubleshooting process. Also the maintenance procedures for inspecting,Testing and replacing items in the set. The link to the TM's is:

MEP-803A, All the TM's you need

This should be all the TM's and additional information you need to work on the MEP-803A

www.steelsoldiers.com

Open left side engine access door and disconnect negative battery cable.

Release control panel by turning two fasteners and lower control panel slowly.

Isolate generator set VOLTAGE adjust potentiometer by disconnecting wire 156A at terminal 1 and wire 157B
at terminal 2 of AC voltage regulator.

Set multimeter for ohms and connect between terminals L and R of generator set VOLTAGE adjust potentiometer.

Adjust potentiometer until multimeter indicates 216 to 264 ohms resistance.

Remove multimeter, but do not disturb potentiometer adjustment.

Disconnect and isolate electrical lead from terminal S of FUEL LEVEL indicator.

Connect jumper wire between disconnected wire 156A and terminal S of FUEL LEVEL indicator.

Connect jumper wire between disconnected wire 157B and terminal G of FUEL LEVEL indicator.

Connect negative battery cable and move generator set MASTER SWITCH to PRIME & RUN position.

FUEL LEVEL indicator should indicate EMPTY (± 1/8 inch).

Move MASTER SWITCH to OFF position and disconnect negative battery cable.

Repeat steps e thru g, setting potentiometer between 29.7 and 36.3 ohms.

Connect negative battery cable and move MASTER SWITCH to PRIME& RUN position.

FUEL LEVEL indicator should indicate FULL (± 1/8 inch).

Move MASTER SWITCH to OFF position and disconnect negative battery cable.

Replace FUEL LEVEL indicator if it fails to function properly.

Remove jumper wires and connect electrical leads to AC voltage regulator and FUEL LEVEL indicator.

Raise and secure control panel.

Connect negative battery cable and close access door.

 

[jamawieb]

The sender unit is 33-240 ohms. Take the wire off that is on the S position on the gauge and test. Light in the dark sells a NOS. Most of the time its the gauge.

 

[Tbob17]

This procedure is found in TM 9-6115-642-24. Its always a good Idea to download the TM's and read the troubleshooting process. Also the maintenance procedures for inspecting,Testing and replacing items in the set. The link to the TM's is:

MEP-803A, All the TM's you need

This should be all the TM's and additional information you need to work on the MEP-803A

www.steelsoldiers.com

Open left side engine access door and disconnect negative battery cable.

Release control panel by turning two fasteners and lower control panel slowly.

Isolate generator set VOLTAGE adjust potentiometer by disconnecting wire 156A at terminal 1 and wire 157B
at terminal 2 of AC voltage regulator.

Set multimeter for ohms and connect between terminals L and R of generator set VOLTAGE adjust potentiometer.

Adjust potentiometer until multimeter indicates 216 to 264 ohms resistance.

Remove multimeter, but do not disturb potentiometer adjustment.

Disconnect and isolate electrical lead from terminal S of FUEL LEVEL indicator.

Connect jumper wire between disconnected wire 156A and terminal S of FUEL LEVEL indicator.

Connect jumper wire between disconnected wire 157B and terminal G of FUEL LEVEL indicator.

Connect negative battery cable and move generator set MASTER SWITCH to PRIME & RUN position.

FUEL LEVEL indicator should indicate EMPTY (± 1/8 inch).

Move MASTER SWITCH to OFF position and disconnect negative battery cable.

Repeat steps e thru g, setting potentiometer between 29.7 and 36.3 ohms.

Connect negative battery cable and move MASTER SWITCH to PRIME& RUN position.

FUEL LEVEL indicator should indicate FULL (± 1/8 inch).

Move MASTER SWITCH to OFF position and disconnect negative battery cable.

Replace FUEL LEVEL indicator if it fails to function properly.

Remove jumper wires and connect electrical leads to AC voltage regulator and FUEL LEVEL indicator.

Raise and secure control panel.

Connect negative battery cable and close access door.

Thanks for all the information. I’ll dive in further. I’m new to this site so I’m still navigating my way around.