Hello, everyone.
I've had a fair bit of work done on the Monaco this year. I'm convinced my latest challenge is unrelated to any of it - which included most recently replacing the fuel line between the Carter carb and the fuel filter. So here's what's been happening. This is a 383 2 bbl.
For years, the fuel gauge has been reading around 1/8th tank low. If my memory is correct, and it may not be, the fuel gauges and the temp gauges are somehow connected electrically. I thought one helps to govern the other electrically. Sometimes, both gauges would move in unison and stabilize in unison, fluid movements as if sloshing around together. Of late, the temperature gauge has been reading in a lower range than normal, too, when fully warmed up.
About a month ago, the garage that did a major overhaul - new exhaust manifold/gasket, new carb, new plugs, distributor cap, rotor, wires - also added a full tank of gas. The gauge was still reading 1/8th tank low. No worries. A couple of weeks ago, that fuel line replacement. By then, I'd noticed that the gauge was reading maybe 3/8th of a tank low it seemed to me. I could not believe I'd used that much fuel.
This morning, the gauge barely read about 1/2 of a tank. After driving just a bit, the reading kept dropping until it was barely above Empty. I knew it wasn't. The gauge does register from its off position to just to the right of E. Went to a gas station. Tank had about 19 gallons in it; took 5 to fill it.
The tank sending unit is old, probably more than 40 years; still checking that. Does this strike anyone/everyone as the simple failure of the tank sending unit? Or do we think that it could be the gauges? Or perhaps both? Grounding strap appears to be in place just fine at the sending unit. None of that's been touched for decades.
I keep a spare instrument panel around just to have a 3D view. This reminded me that fuel gauge has a middle terminal, only visible in the rear (which the parts manual doesn't show). There's a push-on cap which runs to what looks like a small cannister condenser (that's merely a visual description) held by a cannister mount that's screwed into the cluster's rear. Cannister diameter is probably the same as a dime. I have no idea what that is or what it does, but it is connected to that middle fuel gauge terminal. Didn't take the cap off the terminal, but I did move it around on the terminal just fine.
I'm hoping this is something simple that I can reasonably diagnose before I take it in again. Have plenty of the gauges and the sending unit, as well as a new printed circuit board. (I can't believe it's the circuit board, by the way. It's been in there for a long time, maybe a decade-plus, and was produced new in Canada last decade.)
All thoughts welcome, with thanks in advance.
- EF
I've had a fair bit of work done on the Monaco this year. I'm convinced my latest challenge is unrelated to any of it - which included most recently replacing the fuel line between the Carter carb and the fuel filter. So here's what's been happening. This is a 383 2 bbl.
For years, the fuel gauge has been reading around 1/8th tank low. If my memory is correct, and it may not be, the fuel gauges and the temp gauges are somehow connected electrically. I thought one helps to govern the other electrically. Sometimes, both gauges would move in unison and stabilize in unison, fluid movements as if sloshing around together. Of late, the temperature gauge has been reading in a lower range than normal, too, when fully warmed up.
About a month ago, the garage that did a major overhaul - new exhaust manifold/gasket, new carb, new plugs, distributor cap, rotor, wires - also added a full tank of gas. The gauge was still reading 1/8th tank low. No worries. A couple of weeks ago, that fuel line replacement. By then, I'd noticed that the gauge was reading maybe 3/8th of a tank low it seemed to me. I could not believe I'd used that much fuel.
This morning, the gauge barely read about 1/2 of a tank. After driving just a bit, the reading kept dropping until it was barely above Empty. I knew it wasn't. The gauge does register from its off position to just to the right of E. Went to a gas station. Tank had about 19 gallons in it; took 5 to fill it.
The tank sending unit is old, probably more than 40 years; still checking that. Does this strike anyone/everyone as the simple failure of the tank sending unit? Or do we think that it could be the gauges? Or perhaps both? Grounding strap appears to be in place just fine at the sending unit. None of that's been touched for decades.
I keep a spare instrument panel around just to have a 3D view. This reminded me that fuel gauge has a middle terminal, only visible in the rear (which the parts manual doesn't show). There's a push-on cap which runs to what looks like a small cannister condenser (that's merely a visual description) held by a cannister mount that's screwed into the cluster's rear. Cannister diameter is probably the same as a dime. I have no idea what that is or what it does, but it is connected to that middle fuel gauge terminal. Didn't take the cap off the terminal, but I did move it around on the terminal just fine.
I'm hoping this is something simple that I can reasonably diagnose before I take it in again. Have plenty of the gauges and the sending unit, as well as a new printed circuit board. (I can't believe it's the circuit board, by the way. It's been in there for a long time, maybe a decade-plus, and was produced new in Canada last decade.)
All thoughts welcome, with thanks in advance.
- EF
