1975 K-10 Project

[BBM3]

While I am waiting for parts to finish repairing my fuel system I bought a little bling.

I have been restraining myself from buying stuff I don't really need.
Just had to have this.

A couple more details under the hood and in the cab it will look close to as it was when it rolled off the line at Flint Assembly 40 years ago.

[Don5]

You need to submit some pics of that truck for consideration in the calendar. Just saying that it looks good enough that it might make it.

[LTZ C20]

Trust me, as long as it's a members truck, it will make it into the calender no problem.

[enaberif]

So here is a question:
If I replace the sender with a single outlet how will air enter the tank to replace the volume of fuel displaced as it is used?
I assume the gas cap is supposed to be sealed at the filler neck?

You can't have single outlet you will always have either 2 or 3. If you go the 2 route then its a return/supply setup with a vented cap or if you choose to go the 3 route its supply/return/vent and you don't need a vented cap.

[BBM3]

You need to submit some pics of that truck for consideration in the calendar. Just saying that it looks good enough that it might make it.

Thanks that is very kind. Not worthy.

You can't have single outlet you will always have either 2 or 3. If you go the 2 route then its a return/supply setup with a vented cap or if you choose to go the 3 route its supply/return/vent and you don't need a vented cap.

I only have a single feed line from each tank to the selector valve and a single line from the selector valve to the pump.
I can not see where there was ever return, evap, or vent lines. All the plumbing and clamps look original.

Assuming someone removed the return and or vent lines where would they go from the tanks?

This is the unit I have coming tomorrow for the left tank.
http://www.amazon.com/gp/product/B000C7W0BS/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1

[enaberif]

Did this truck ever run? Because a you need a return line to the fuel tanks.

The selector valve has the same function .. supply/return. Something is funky with your truck.

Here is how it generally works..

[BBM3]

Sorry I left out details.

Yes the truck runs.
This is what I have:
The Left tank has a sender with two outlets. One outlet was open to atmosphere and the feed outlet runs directly to the fuel pump.
The selector valve is not currently connected to the fuel pump.
The right tank is not used and it's feed line is connected to the selector valve. I have not dropped it yet so I don't know what is going on with the tank or sender.


EDIT:
Missed your diagram.
My selector valve which looks original has two inlets and one outlet.
The fuel pump has one in and one out.

[enaberif]

Sorry I left out details.

Yes the truck runs.
This is what I have:
The Left tank has a sender with two outlets. One outlet was open to atmosphere and the feed outlet runs directly to the fuel pump.
The selector valve is not currently connected to the fuel pump.
The right tank is not used and it's feed line is connected to the selector valve. I have not dropped it yet so I don't know what is going on with the tank or sender.


EDIT:
Missed your diagram.
My selector valve which looks original has two inlets and one outlet.
The fuel pump has one in and one out.

Find out where the two lines from your fuel pump are going to. That will give you a better idea of what is happening.

[BBM3]

I only have a single fuel line from the selector valve to the fuel pump and a single line from the fuel pump to the carb.

[enaberif]

I only have a single fuel line from the selector valve to the fuel pump and a single line from the fuel pump to the carb.

Ohhhhhhhhhhh yeah. I'm having some serious brain farts. Mine is setup the same way.

[BBM3]

So maybe what I need is to use single outlet senders and make sure I have vented gas caps?

[BBM3]

The selector valve was bypassed in this pic but I know how it should be plumbed.

You can see the clamp holding the brake and fuel line on their way forward looks original.
It sure doesn't look like someone removed a vent and or return line in the past.

[BBM3]

Sometimes little things bother me. I think my brain is slightly mis-wired.
While I was waiting for FedEx to deliver my fuel sender today I fixed something.
The speedo and fuel gauge needles were faded and it bugged me.
Too much glare in the pictures from the cluster lens I polished the other day. Oh well.

Before


Before....Cleaned and ready for paint


After.... Needles look red but they are orange

[LTZ C20]

Nice, did the same with my needles. Faded and almost white to shiny and Chevrolet Orange. Used a half a can of engine enamel I had laying around.

[BBM3]

LTZ C20, Glad to know it's not just me!

Back to my fuel system today:
I have plans for my fuel system and I figured out what was going on with the sender vent output on the left tank.
The vent on the sender that I originally noted was open on closer inspection looks like it once had a vent cap like the ones on the diffs, transfer case and transmission. I attached a picture below. Based on the amount of dirt it looks like it has been there a long time. Maybe original?

PLAN ‘A’
What I have done is to instal a couple of feet of 5/16” fuel line to the sender vent, plugged it, zip tied it to the fuel line, and installed a vented gas cap.
I did this so I have future access to the vent line if I need without having to drop the tank again.

I’ll test this for a while and see if the vented gas cap works without spewing fuel and / or stinking.

PLAN ‘B’
Connect the left and right sender vents with a tee and run a line up the frame rail to the engine compartment.
Find a charcoal vapor canister and install a working evap. system.

The left end of this “Vent” was attached to the sender the end with the yellow clamp has what looks like the remains of a vent cap