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I was plundering around under my dash and ran across a switch on the accelerator pedal linkage.This is something I've never seen on anything before.Anybody tell me what it is.

I think it's called a "coasting rich" switch. Some smog stuff I guess. Someone else probably knows more about it. From the name I would guess it adds fuel when you coast, probably to aid the catalytic converter.

Just a guess.

It hooks into a solenoid on the carb that opens to richen the mix a little when certain conditions are met:

Foot is off the gas pedal
Foot is off the clutch pedal
Transmission is in 3rd or 4th gear

The idea is that when coasting, it gives the motor just a little more gas. Probably it is thought to have needed a little more gas during coasting to burn more cleanly. Whether that is actually the case or not, who knows. At that point emissions equipment on vehicles seemed like it was half guesswork. Later Isuzus, I think 82 LUVs, and maybe Cali emissions models instead have a "slow cut" solenoid that works off the same sort of switch setup. I think it actually does just the opposite.

You can sometimes feel the effect of this happening if you either lightly press the accelerator pedal or the clutch when coasting in 3rd or 4th. If you can press the gas or the clutch down enough to engage the switch but not actually do anything else, you should feel a slight decrease in speed. In my 79 was more noticable like cruising in town it made 5MPH difference in idle speed in third. My 76 and 77 is was hard to tell. I disconnected one of the switches because I was always riding the clutch pedal to keep it from coming on.

OK , thanks.I put a new electric fuel pump on a while back and was in kind of a rush so I just wrapped the power wire around one of the fuses and stuck it back in the fuse box.Later when I had more time, I got under the dash and found me a wire that had fire with the switch on and connected to it.Well, when I start down the road it dies after a while and then mysteriosly takes back off again.After some further investigation, I found that I had tapped into that switch wire and when I would go down the road and give it gas the fuel pump would stop and when the carb bowl ran dry it would die.I found a different wire to tap into for the pump and now everything is fine but I was just wondering what the switch was for.Thanks for the info guys, it is greatly appreciated. Bubba