Rich smell and poor MPG

[kings1527]

Hi all,

So it seems somewhat recently (that I've noticed) that my fuel economy has dropped off to about 16 City with heavy AC use and maybe 19 on highway with AC whereas it used to be 18/23 or so. I notice that the car smells rich on startup and initial idle, frequency valve is buzzing, and my dwell is properly adjusted. The only things I can think of would be:

Plugs/wires....haven't noticed a loss of power, really. Nothing from normal.
Bad injector
Valves in need of adjustment

What else? Thanks.

[Bitsyncmaster]

You said your dwell was correct but was that checked after you found the MPG drop?

[Jonathan]

The full throttle fuel enrichment microswitch might be stuck. The little plunger tends to get grimy and then won't pop back out on its own once you let off the pedal. Basically it keeps the engine in this fuel enriched mode the whole time. That same switch could be getting shorted internally too and that would cause the same problems.

Unplug the switch at the Tetris puzzle looking connector and see if you notice a difference. You can leave it unplugged and go for a drive or two to try and get a feel for the new MPG if that's what the problem was. Unplugging it won't cause you any new problems.

[kings1527]

You said your dwell was correct but was that checked after you found the MPG drop?

Hi Dave. Yes, I checked it after the drop and it checked out OK.

The full throttle fuel enrichment microswitch might be stuck. The little plunger tends to get grimy and then won't pop back out on its own once you let off the pedal. Basically it keeps the engine in this fuel enriched mode the whole time. That same switch could be getting shorted internally too and that would cause the same problems.

Unplug the switch at the Tetris puzzle looking connector and see if you notice a difference. You can leave it unplugged and go for a drive or two to try and get a feel for the new MPG if that's what the problem was. Unplugging it won't cause you any new problems.

Thanks. I'll check up on that.