1973 bronco emissions fuel info

[bella73]

hi!

do i need to buy new sending units or cap the returns on my 73 sending units (with send and return lines?) Are my (original) 73 tanks 'vented" other than the return lines, and will capping the return lines cause vapor lock?

anyone know much about the 1973 beta tests ford did prior to their emissions changes in 74 and 75? Heres what i'm facing:

my 73 bronco originally had a 6 port fuel valve with manual petcock under the drivers seat front for switching from main to aux tanks. i have an unresolved drip when i put more than a couple of gallons in my aux tank, or if i put more gas in my main tank than the capacity of the aux, so i know i have fuel being sent back and forth between main and aux.

when i purchased her, the prior owner had installed a three port and added a "T" in the lines before where they hit the valve. Gas seemed to be taking a grand tour of the underside of the truck and exiting like a geyser from the charcoal canister behind the right front tire. some rerouting soved that- i saw some lines had been switched by accident. but now i still have this routing problem, so:

I want to bypass the charcoal cannister and the vapor cannister ( in side wall behind rear of left door frame ) and simply use the 3 port to route fuel from either tank ( one at a time, please) to the carbeurator.

i figure when i turn the truck on and the fuel pump starts, because there are two sending units, fuel is being drawn from both tanks simultaneously and running around all over the place to and from the vapor cannister and the charcoal cannister, as in : whatever fuel gets to the carb first , wins the race.

IS THIS CORRECT?

so, if i bypass all of the extras, the charcoal cannister and the vapor cannister and just use a 3 port petcock - do i have to replace the original send and return type sending units with only 'sending units" or can't i just cap off the return lines on each sending unt and go with that- (or is there another vent on each tank so i dont get vapor lock or could i just use vented caps?)

thanks in advance-

Bella73

 

[Bully Bob]

WOW..!

I think I know what you think you said...I think.... ) )

Not sure about Cal. but; I would run (1) fuel line fr. ea. tank to a manual or electric switch-over valve, then (1) fuel line to the fuel pump,

then (1) from fuel pump to carb.

I f there's a fuel return from carb. to tank...I know nothing about that.

The tank filler tube should have an air vent tube leading back to the gas cap hole. a vented gas cap should work there.

All those other small tubes can be abandoned/plugged.

Hot runn'n 351 may get vapor-loc .....don't know what eng. or carb you have.... /emoticons/[email protected] 2x" width="20" height="20" /> :-B

 

[Seabronc]

Welcome to the Zone > Post some pictures.

Just to add a bit to what Bully Bob said. The fuel should not go to the canisters. They are there to collect vapors and to relieve pressure when the tanks get hot and prevent venting gas vapors into the atmosphere per emissions laws.

When the engine is running there is a valve between the canisters and the carb, that is supposed to close and prevent the carb from sucking gas thru the vent lines. If it's not functioning it will most likely **** gas thru that path. The Canister Purge Valve is controlled by a Vacuum Control Valve mounted on the intake manifold. This should let the carb **** the vapors collected in the canisters and then as the engine starts to warm up close off the Canister Purge Valve. Sucking gas thru the vent lines will make you engine run like crap.

You can A. Fix it or B. Remove the evaporative emissions stuff. Just a not on removing it, if the inspection information says you should have it, you could fail inspection for not having it. Here, on trucks that 95 and earlier it is a visual inspection so it all depends on the inspector if he/she picks up on it.

If you decide to fix it, I can probably talk you thru it if I had a picture of the current arrangement to look at.

A picture of the CPV attached, that purple thing.

Good luck,

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