Old as dirt,but still above it

[BETO 54]

New to this, have a question. Am trying to bring a 1978 chev K10 back to life.
It spent a lot of years on a deer lease, so it has had a lot of hands under its hood.
While I have the bed off I've replaced both sending units (they didn't work) and the
selector valve, it was not working. Seller by-passed it to get trk running. I haven't
replaced the selector valve yet cause i can't find a 6 port single wire unit only 3 port.
The 3 port will take care of the two tanks supply lines to the mech. pump, but not
the return lines. If anyone knows how much volume of fuel actually is returned to
the tanks I would appreciate that info. I am thinking about putting a "T" fitting on
the return line and running a line to each senders vent fitting. The vent ports on
sending unit have a float type Ck valve so not to over fill the tank. Other than I'M
crazy, give me your thoughts. I have no desire to rewire the truck for a 5 wire unit.
If the volume is to much I'll have to rethink it. If anyone Knows of a 6 port single wire
valve, please let me know. Thanks

 

[Hogger]

I don't have the answer but from one old guy to another, welcome from Cochise County Arizona.

 

[Soundmound]

Welcome from the PNW!

 

[WFO]

Welcome from up in the Panhandle.

 

[HotWheelsBurban]

Welcome from Houston, TX!

 

[Shorty81]

Welcome from Ohio

 

[animal]

 

[JamesSam]

Welcome from VA. Dual tank issues are rampant.

 

[BETO 54]

Thanks from central Teas!

 

[HotWheelsBurban]

Even when these trucks were new, there were issues with the switching systems. Dad's 75 GMC Sierra Classic had a "dealer" installed (actually done by a subcontractor shop off premises) second tank and he had trouble with that the whole 5 years he drove that truck.

 

[bucket]

Howdy from Ohio!

Simply installing a standard type fuel pump without a return port would take care of that dilemma.

 

[JamesSam]

Howdy from Ohio!

Simply installing a standard type fuel pump without a return port would take care of that dilemma.

@bucket
When you say 'installing a standard type fuel pump without a return port'.... do you mean doing this with dual tanks or are you promoting a one tank conversion?...or did you mean something else? I really do not know and am totally up in the air about what I will do about my drivers side tank not working. I would love to have dual tanks but want the system to be reliable. I am also almost ready to just drop the tank that doesn't work but I fill up quite a bit with one 16 gallon tank...help....

 

[fast 99]

I've been trying to find a single wire 6 port for a while. A lot of places list them. None are available, apparently discontinued.

 

[Turbo4whl]

@bucket
When you say 'installing a standard type fuel pump without a return port'.... do you mean doing this with dual tanks or are you promoting a one tank conversion?...or did you mean something else? I really do not know and am totally up in the air about what I will do about my drivers side tank not working. I would love to have dual tanks but want the system to be reliable. I am also almost ready to just drop the tank that doesn't work but I fill up quite a bit with one 16 gallon tank...help....

That third fuel hose is just a vent, not a fuel return. For years pumps had two lines, fuel in, pressure out. The back side of the pump diaphragm was vented with a small hole in the case. This was how you cold tell the pump diaphragm was worn out, the pump leaked a little fuel.

Zoom ahead, EPA wants all possible fuel contained, So they added a hose barb and sent the vent back to the tank. You can just "T" the vent lines at the selector valve and use a 3 port valve.

Bucket's referral for a pump like what was installed on my, older 1974 350, no vent hose, just a breather in the case.

For anyone who thinks, "when I pulled the vent line I got fuel" here is why: The back of the pump diaphragm pulls tiny, vacuum then tiny pressure back and forth. This will make fuel or vapor draw in and out and gravity holds some. Pull the vent line and yes, some fuel comes out.

 

[BETO 54]

Thanks for your replys. Since i posted the question I contacted an old friend. He laughed and said he had on still inn the box. I think thats called NOS! Gonna mail it to me, so we will se how it works.
FYI the AC Delco # is 467513.