poor mpg

OK I just replaced my vacuum advance,no change in mpg.So now maby replace the coil but I dont think there is anything wrong with it.so if my motor was in need of a rebuild would the truck not smoke pretty bad, but it doesnt smoke at all,it just burns super rich and drinks gas like an RV. I have new plugs and wires,rotor cap button vacuum advance etc etc.this weber carb is the third carb iv had and all three have the same mpg two oem and now the weber. so anymore ideas from anyone as to why my truck burns so rich and uses so much gas .can a bad coil make it use this much gas.

I am fighting a RICH condition also. I'm going to throw as close to Original Manufacture Parts at it as possible. I should be having an Oxygen Sensor show up soon. I'm also looking into the coolant temperature sensor that the computer sees. After I do those to parts, I'll have to rethink my strategy if I get no change.

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You may have a mixture control solenoid that isn't operating. Do you have a multimeter that can measure dwell?

I do not have a DVOM or Multimeter. Someone decided they needed my tools more than I did. I'm thinking I can track one down or just get a cheap $20.00 one or something.

What are the millivolts (idle to WOT) or values I would need in checking the mixture control solenoid???

Any other ideas in tracking down a RICH condition & other thoughts as for what I'm describing??? Please check / read my other posts. I'm slowly getting some improvement out of this engine, but some days I feel like it just took 2 steps back on its own.

You can use the multimeter to check coolant temperature switch in the radiator to verify operation.

The mxture control solenoid defaults to a 20 % on time when the truck isn't working properly. Under normal circumstances it should be 45-55% and that is where it should be if everything is working.

Has the rollpin on the carburetor been removed?

I believe there is a green connector near the horn relay and that is where you tap into the dwell circuit. The other meter lead goes to ground.

What I used to do is rev the engine (blip the throttle) with the meter hooked up and watch for the numbers of the meter display to count up to 90 and then fall back to whatever dwell was active. If it dropped to 20 that meant the mixture control solenoid was not leaning the mixture as ti was supposed to. The also was when the detective work started.

I know nothing about Carbs.

What does removing the roll pin do???
Where is the coolant temperature sensor located that the computer sees???
I'll look into the mixture control solenoid this weekend.

If memory serves me correctly, the coolant temp sensor that the computer uses is located in the bottom tank of the radiator.

The roll pin is an anti tamper device that the factory installs to prevent casual adjustment of the mixture control screw. The carb has to be removed from the intake manifold to remove it without damaging the carb. Maybe somebody can post a picture up. It's been awhile since I had one of these trucks otherwise I would.

Nope. That's for the PTC heater under the carb. Mostly came on cold weather climate trucks.

Even dragging brakes must be considered when investigating poor mpg.

So the Coolant Temperature Sensor that the Computer sees is under the Carb???