You could consider taking some turns off the gauge winding, reducing the field strength. Terry
On Wednesday, November 20, 2013 6:30:30 AM UTC-6, orange_glow_fan wrote: > I should have supplied more information with my original message but I was > trying to brief and not bore you guys hehe.. > > This gauge problem is in a 1965 Ultravan (motorhome) which is a Corvair > powered unit. As I said, it has the original sending unit but the gas gauge > has been replaced. I used a 90 ohm resistor to verify that it needs to see > a 90 ohm sending unit to show 'full' on the gauge. > > The tank is a 30 gallon unit that would be a huge PITB to remove. Also, > since it's unlikely that the replacement sender will fit, it's going to > require some modification and the thought of drilling/cutting into the tank > (gas explodes hehe) after draining seems a bad idea. unless the tank is > filled with water vented etc... > > There is some confusion as to what resistance range the original sending > unit had. Some report a 0 - 45 ohm version, some a 0 - 30 ohm version. > Currently we measured the level of gas in the tank and got 1/2 a tank. The > sending unit measures 14.9 ohms to ground hence I believe that it is a 0 - > 30 ohm unit. > > Here is a not so brief description of the gas gauge/sender operation : > > *The fuel gauge needle is mounted between two magnetic coils. One coil is > on the "F" side of the gauge* > *and the other is on the "E" side of the gauge. Both coils are wired to > the ignition circuit and receive* > *battery voltage whenever the ignition switch is on. The magnetic coil > that pulls the needle toward F* > *(Let's call this the F coil) is grounded at the instrument panel and > applies a constant magnetic force to* > *the needle. The magnetic coil that pulls the needle toward E (Let's call > this the E coil) has more* > *windings for greater magnetic strength and is grounded through the > variable resistor in the sender* > *attached to the fuel tank float.* > *When the fuel tank is full the resistance in the sender is high (30 or 90 > ohms) which reduces electrical* > > > *current and magnetic strength in the fuel gauge E coil allowing the F > coil to pull the gauge needle to 'F'* > *When the fuel tank is nearly empty and the float is near the bottom of > the tank the resistance in the* > *sender is at 0 ohms. The fuel gauge E coil receives full current, has > enough magnetic strength to* > > > *overcome the strength of the F coil and pulls the gauge needle to 'E'* I > hope that explanation helps clear things up a bit.. > > I am going to make some new measurements today, hopefully one of which > will be the resistance of the gauge and voltages for reference. The gauge > is also a bit of a pain to get to. > > Thanks for your input so far! > > Kerry > > > -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send an email to [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/765dc092-6eff-47e7-a3a4-cf5e3a82dfdf%40googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
