Voltage limiter
RTE as example
https://www.rt-eng.com/index.php/RTE_limiter.html
Another article about converting the internal gauge
https://www.rt-eng.com/index.php/RTE_Gauge_Faq.html#Fixing_dash_clusters_that_have_internal_limiters
Here is how they work. The fuel gauge has three terminals. One is 12v INTO the gauge UNIT and that 12V supplies power TO the internal limiter. It feeds the regulated voltage (5v + / - ) to the fuel gauge, and ALSO outputs the 5V to the second of the 3 studs. That stud then jumpers the 5V over TO the other two gauges, oil and temp. The 3rd stud on the fuel gauge, of course, is for the fuel sender.
User Redfish has written a lot about these writing cautions to avoid screwing up the gauge, which of course is delicate. One method is to CAREFULLY separate the old limiter contacts and gooping it with "Goop" (that is the name) or RTV to keep the contacts apart. If you can, it might be good to isolate the 12V stud from the limiter, or remove/ cut the limiter heater so it cannot fail/ short and cause problems
I recommend you rig some sort of test resistors, so that you can test the system END TO END. They all use the same resistances. Feed 12V and ground to the cluster, hook a test resistor from one gauge sender to ground, and the appropriate resistor should give the correct reading. Here is an old photo of a brand X test box showing the resistances
Generally, be sure the senders are grounded, and not overtightened. Suspect problems in the bulkhead connector for temp and oil. Fuel goes through the rear harness. Add a dedicated ground pigtail to the cluster and ground it to the dash/ column support. Take the nuts on the gauges and loosen/ tighten them 3-4 times to "scrub" them and make good connections.
This is not a good way to put this. There is no "first," or whatever. They are all three in parallel. The article posted is what you want EXCEPT not necessarily the home built limiter. You can buy a solid state one from RTE and adapt that.
RTE as example
https://www.rt-eng.com/index.php/RTE_limiter.html
Another article about converting the internal gauge
https://www.rt-eng.com/index.php/RTE_Gauge_Faq.html#Fixing_dash_clusters_that_have_internal_limiters
Here is how they work. The fuel gauge has three terminals. One is 12v INTO the gauge UNIT and that 12V supplies power TO the internal limiter. It feeds the regulated voltage (5v + / - ) to the fuel gauge, and ALSO outputs the 5V to the second of the 3 studs. That stud then jumpers the 5V over TO the other two gauges, oil and temp. The 3rd stud on the fuel gauge, of course, is for the fuel sender.
User Redfish has written a lot about these writing cautions to avoid screwing up the gauge, which of course is delicate. One method is to CAREFULLY separate the old limiter contacts and gooping it with "Goop" (that is the name) or RTV to keep the contacts apart. If you can, it might be good to isolate the 12V stud from the limiter, or remove/ cut the limiter heater so it cannot fail/ short and cause problems
I recommend you rig some sort of test resistors, so that you can test the system END TO END. They all use the same resistances. Feed 12V and ground to the cluster, hook a test resistor from one gauge sender to ground, and the appropriate resistor should give the correct reading. Here is an old photo of a brand X test box showing the resistances
Generally, be sure the senders are grounded, and not overtightened. Suspect problems in the bulkhead connector for temp and oil. Fuel goes through the rear harness. Add a dedicated ground pigtail to the cluster and ground it to the dash/ column support. Take the nuts on the gauges and loosen/ tighten them 3-4 times to "scrub" them and make good connections.