fuel gauge on 843B

[donald73d]

I think I am down to the last broken thing on the instrument cluster. The tank is full, gauge shows empty. The fuel gauge itself was replaced. It does slightly move when the key is turned on. With everything connected, I get 00 ohms at the sender which is what I would expect. I am going to remove both wires at the sender, measure again, put some dielectric grease on things and measure with wires not attached. Then measure at the gauge. I have a hard time believing a wire is broken in the harness. Am I missing anything? What chance the new gauge is broken? I can connect the sender lug to ground and see what happens. Should read full. But sometimes that really bangs the pointer. The old gauge had saw dust inside and the pointer could move or not move or stay.

 

[donald73d]

OK, I pulled one of the wires at the sender and measured across the sender and immediately it goes to 00 then counts up to about 210 ohms. I kind of think that is normal as I see it many times. I did make sure my hands/fingers were not touching the probes.

 

[bobbie-g]

OK, I pulled one of the wires at the sender and measured across the sender and immediately it goes to 00 then counts up to about 210 ohms. I kind of think that is normal as I see it many times. I did make sure my hands/fingers were not touching the probes.

My notes on my T180 fuel gauge/sender say the gauge should read empty when the wires are disconnected from the sender. I got a new sender, which has a slider that floats up and down on the top of the fuel. Before I installed the sender, I checked its resistance: when the slider is at the top (tank full) my ohmmeter read 33 ohms; slider at the bottom (tank empty) and I read 230 ohms. ---Bobbie G.

 

[Tazza]

My notes on my T180 fuel gauge/sender say the gauge should read empty when the wires are disconnected from the sender. I got a new sender, which has a slider that floats up and down on the top of the fuel. Before I installed the sender, I checked its resistance: when the slider is at the top (tank full) my ohmmeter read 33 ohms; slider at the bottom (tank empty) and I read 230 ohms. ---Bobbie G.

Make sure you have a good ground, if its not, the gauge won't work right.
If there is a bad connection in the harness, it will stop it working right too.

 

[donald73d]

My notes on my T180 fuel gauge/sender say the gauge should read empty when the wires are disconnected from the sender. I got a new sender, which has a slider that floats up and down on the top of the fuel. Before I installed the sender, I checked its resistance: when the slider is at the top (tank full) my ohmmeter read 33 ohms; slider at the bottom (tank empty) and I read 230 ohms. ---Bobbie G.

Hmmmm your reading are the opposite of what I would have expected. I do not see any resistance readings in the service manual. Do sending units fail often? The machine has over 4000 hours.

 

[Tazza]

Hmmmm your reading are the opposite of what I would have expected. I do not see any resistance readings in the service manual. Do sending units fail often? The machine has over 4000 hours.

If its the style with an arm and a coil of risistance wire that as the level changes, the pointer alters the resistance. The only way they seem to fail is from long term use of the pointer rubing through the wires. I haven't seen one wear through, but its been close. Corrosion on the terminals has stoped one working right for me, but i managed to fix it up.

 

[donald73d]

If its the style with an arm and a coil of risistance wire that as the level changes, the pointer alters the resistance. The only way they seem to fail is from long term use of the pointer rubing through the wires. I haven't seen one wear through, but its been close. Corrosion on the terminals has stoped one working right for me, but i managed to fix it up.

Its a 1990s 843B with 4000+ hours so its been around. I am thinking the reason it goes to 00 then to 350 ohms is its going through its auto-ranging. It starts out on infinity on meg-ohms and needs to get to the single digits scale. I tried it with a second meter and it ends up doing the same thing and stops at around 330 ohms. I think I need a new sender.

 

[donald73d]

Its a 1990s 843B with 4000+ hours so its been around. I am thinking the reason it goes to 00 then to 350 ohms is its going through its auto-ranging. It starts out on infinity on meg-ohms and needs to get to the single digits scale. I tried it with a second meter and it ends up doing the same thing and stops at around 330 ohms. I think I need a new sender.

I replaced the sender and all is well with respect to the fuel gauge showing a full tank of fuel. Oddly two of the edges of the float in the old sender look like they were rounded/gnawed, now even smooth. But each was rounded/gnawed about the same. The other end looked fine. If someone else replaces the sender, the gasket only fits one way. The holes are not evenly spaced. Almost but not evenly. OK, so that was done to make sure the sender only goes in one way? With the float arm attached I am not sure one could get it in wrong unless you forced and bent something. Gasket and sender was a little over $100.

 

[donald73d]

I replaced the sender and all is well with respect to the fuel gauge showing a full tank of fuel. Oddly two of the edges of the float in the old sender look like they were rounded/gnawed, now even smooth. But each was rounded/gnawed about the same. The other end looked fine. If someone else replaces the sender, the gasket only fits one way. The holes are not evenly spaced. Almost but not evenly. OK, so that was done to make sure the sender only goes in one way? With the float arm attached I am not sure one could get it in wrong unless you forced and bent something. Gasket and sender was a little over $100.

I see there are three lines going to the tank on top . One by itself and two together. I can a assume there would be a pickup line, return, and maybe the third is a vent? The two that are together are they vent and return so they do not go down into the tank? The one by itself is the pickup? I ask this as I want to make sure that the sender assembly can just be fitted into the tank with the float going to the side opposite the fuel fill and I do not need to worry about the float hitting anything like a pickup line or a mounting piece of the tank.