Blue wire???

[f26yrn04558-72]

I have a 72 f250 custom, no extras except a tach. My question is what this plain blue wire connects to. I have looked at as many wiring diagrams as I could find, even the junk yard. I think it may go to a aux fuel tank. I have attached a picture of this wire.

[390Nut]

Only blue wire I see on the diagram here: http://www.fordification.com/images/sch ... _quick.jpg is for a "carb throttle switch" whatever that is

[390Nut]

More info. Looks like Blue wire is for the throttle solenoid, according to this diagram: http://www.fordification.com/images/sch ... master.jpg the blue wire is #932 in the diagram, and it looks like it's part of the A/C system possibly. (right below the starter in the schematic)

[f26yrn04558-72]

I see the one for the carb throttle switch, the carb does not have a switch or sensor on it that I'm aware of. If any one has a picture of this setup please post it. p.s did the picture come through?

[390Nut]

Yep, it came through. Probably got removed with the carb at some point, hence the wire getting cut. I wouldn't worry about it, but I WOULD cap it off, as it looks to have power from the ignition switch in the run position.

[f26yrn04558-72]

I planed on capping it. thanks for the reply. Just curious what does it do?

[390Nut]

The throttle solenoid on the carb serves a couple functions. In the simplest form (spring powered) it keeps the throttle from "chopping" when you let off the pedal. That is, the throttle springs shut to a certain point, then slowly closes the last 1/8 to 1/4 inch or so. Emissions junk, really, but it helps to keep the fuel flow consistant with the movement of the truck, as it comes to a stop. Not truly necessary, unless your emissions testing is tough enough to warrant having it there.

I THINK that the electric ones, such as what your truck evidently had, is also used to control the idle on an A/C equipped vehicle, so that the idle doesn't drop when the A/C is turned on. There may be other intentions, or reasons for the electric power to the switch (perhaps the spring tension alone wasn't durable enough over time? dunno for sure)

[f26yrn04558-72]

That makes sense. thanks for the info!!!! the truck runs perfect, except until it worms up for a minute or two.

[68F250]

If you ever convert to electronic ignition, that's the perfect place to get the +12 volts to power the unit. It is hot in the start and run positions.

[f26yrn04558-72]

Yes it is, I was thinking about converting it over, not shure though. I was thinking og keeping it all stock. Any recomandations on what type of unit/brand to install? How much do they $$$$