First let me say I know you older guys get tired of hearing the same questions from the less knowledgeable crowd. But I dropped my tank and before removing the old pump I went ahead and tried the new one no power. I have seen the schematic but its kinda Greek to me. Now what?

 

LOL NO.

A we are probably not much older than you. Secondly we love sharing our knowledge because
a. we love helping
b. we love sharing our knowledge
c. we love the thought that the knowledge we gained by working on our old trucks will go to good use and help save other old trucks

that being said let us help you, please share
a. year of truck
b. type of truck
c. type of truck engine
d. pictures?
e. what does the multimeter say?

 

Sorry 1986 F250 with a 460. Used to be fuel injected now carb. All work done by PO.

 

No EFI 460 in 86, only the 5.0. But they did have low pressure electric pumps on 460s with the "Hot Fuel Handling" package. The power is fun on that configuration. (older and wiser gentlemen correct me if I'm remembering this incorrectly) Power during cranking is fed straight from the ignition switch through the inertia switch to the pump. Once the engine is running and oil pressure is up, it is fed from the fuel pump relay, triggered by a secondary oil pressure switch on the back of the motor, through the inertia switch and to the pump. Now you saw you have dual tanks, so in that case the power out of the inertia switch is routed through the tank selector on the dash, and split out to power the pump and the sender....

I think that's it if I remember correctly.

The first thing to check of course is all the different connections to see of you have continuity. Most common failures are at the inertia switch which is in the passenger side footwell, and corrosion in the underbody harness. If the rear pump runs and the front does not, I would look at the wiring after the selector switch and the switch itself.

 

I didnt mean older as in age, I just meant more familiar with vehicles.

 

I believe you remembered correctly.
Long story cut short, there won't be any power to the pump with the key on, engine not running. Only while cranking, or after the engine is started.

 

Neither tank is working.

 

Even while the starter is engaged?
(because that is a whole different source than power in 'run')

 

I've yet to check with a meter, my brother is supposed to bring one up this evening. Noticed a few holes in the tank, in my googling for one there are two different sized ones for the front a 16 & 19 both look the same. How do I tell which one and where Is the best place to order it?

 

16 gal only on short bed trucks.

Archion,
The inertia switch supplies power in 'run' to the fuel pump relay.
The oil pressure switch provides the 'pull down' side of the relay.

The 'hot in crank' Tee's into the relay output with an inline diode.

Power then goes to the tank selector relay and on to the switching valve.

 

If it's been modified then all bets are off. But...if it's the same stock set up as mine then the fuel pump gets power two ways:

1) While cranking the fuel pump gets power from the fuel pump bypass wire.

The fuel pump bypass wire is attached to one of the small starter solenoid terminals and it is energized only when the starter is cranking. If I recall correctly the bypass wire is attached to the small "I" terminal of the starter relay and you can run a jumper wire from the pos + terminal of the battery to the bypass wire and you should have power to the pump and / or hear them run. You can do this temporarily for testing purposes but don't run it on a jumper long term. System isn't designed to run a full 12 volts continuously and you can burn fusible links / wires if you do.

CAUTION: The other small starter solenoid terminal (the "S" terminal I think...S for "start") is the starter signal wire and if you accidently jump power to this terminal you will engage the starter...and if it's a manual, and it's in gear, the truck could jump causing injury, damage, or worse! Be careful!

2) The other way the fuel pump receives power is through the normal fuel pump circuit. Starting at the LARGE hot terminal of the starter relay, through the inertia switch, through the fuel pump relay (which is activated via the oil pressure switch and associated wiring), through the step down resistor wire, and then through the fuel tank selector to the fuel pump...

What can possibly go wrong?