Sorry we weren't able to help you on the phone. Is there a diagram on Holley's website? The layout in Steve83's diagram above is for a generic aftermarket setup, but not necessarily Holley-specific.
The only one we are going to have to look at here is the factory switch, which is only for the gauges and has nothing to do with either switching tanks, or EFI in general terms.
Since neither an electrically operated valve, or EFI were available from the factory, we're relying on you to let us know what you've got.
Can you take some pictures of what you're talking about? If the truck originally came with dual tanks from Ford, it would have had a simple toggle switch like this:
Fuel Gauge Switch to switch tank senders to the gauge, but the actual switching valve for the fuel was a manual valve on the floor under the driver's seat and looked similar to (but not exactly like) this one on the right:
Tank Selector Valves With the one on the left being a common retrofit.
Anything else, whether from Holley or any other company is an unknown at this point. At least to me.
If others have used a Holley dual tank kit, maybe they can chime in with more info.
So we can't do anything until you let us know what you have exactly. So far we only know you have some sort of a Holley switch which none of the members who've responded so far appear to be familiar with.
Pictures would likely clear it up though. More often than not they help immensely.
You can't post them directly here unless you become a contributor for 12 bucks a year. But you can use your "garage" feature in your User CP above for at least some images.
Or you can utilize another online hosting site like SuperMotors and link your images here.
Or in a pinch you can e-mail them to me at
paulb@wildhorses4x4.com and I can post them up for everyone else to see if they recognize what you have.
Hopefully we can figure it out. But if it looks like that switch I linked to above, then Steve83's other diagrams should cover it.
I'm sure we'll get it figured out.
Paul
