Fuel tank hoses

[Big Blue]

Please take a look at the picture, can anyone tell me where each hose goes to. I am NOT using the canister that is upfront near the Rad support.

A: GOES TO:
I BELIEVE IT IS GOING TO THE FUEL FILLER AS A BREATHER?

IF NOT USING IT CAN I PLUG IT UP?

B: GOES TO:
IF NOT USING IT CAN I PLUG IT UP?

C: GOES TO:
I HAVE GOING TO MY ELECTRIC FUEL PUMP TO ENGINE

IF NOT USING IT CAN I PLUG IT UP?

D: GOES TO:
IF NOT USING IT CAN I PLUG IT UP?

[mongocanfly]

are you wanting to plug all those lines?
the 4 should be
a:fill tube vent
b:tank vent
c:suction line
d:return line

I think...
what does it go on?

[Big Blue]

1979 Chevy Blazer rear tank, No, I want to know where do they go and if I am not using the canister can I plug up the return line? That would leave me with (A)
( BREATHER )This is where the thick hose that gets attached at the filler neck goes to, that is the only big hose size. Your are saying that (B) IS the tank breather? I am using (c) as my line to the electric fuel pump. Is that the suction you are talking about? AND (D) IS THE RETURN LINE that I can plug up since I am not using the CANISTER. Sorry if I made this confusing. Thanks again, John

If (B) Is the tank breather ,what do I use , would it be the breather tip that you would find on the end of the hose either on the trans or rear diff?

[mongocanfly]

I'm just assuming this is what you have...this is what came up when I googled your truck
#1 fill tube vent
#2 has what I think is a rollover valve in circle
#3 is your suction line
#4 should be a return...if you don't have a return style system then you can cap it off

[Big Blue]

Thanks mongocanfly,
So can I cap off off #2 and # 4. Since I am not using the canister? If I can not then, what do I put on the ends. What goes on the roll over tube?


John

[Dead Parrot]

The gas tank needs a vent to outside air. As gas is pulled out, air takes its place. #2 is the likely candidate. If you aren't running a canister, then use a differential vent on a short piece of hose. Of course, if Blazers use a vented gas cap, then your vent problem is solved.

If the canister and related tubing is still there, no reason not to use it. It doesn't hurt power and adds a bit of economy as it saves the fuel vapor that would otherwise be lost to the air. Plus those differential vents cause gas smell. My 75 has two of them and on a hot day, you can really smell the gas evaporating off.

[mongocanfly]

^^^ what he said ^^^

[hatzie]

A - Fill pipe vent line. Use it. It'll want to kick off the automagic gas pump handles if you don't connect the fill pipe vent line.
B - Tank vent. Use a differential vent cap on a hose terminated so the cap is above the level of the fill pipe... or route it to the VENT connection a 1970's 3 hose charcoal can.
C - Suction line to the fuel pump.
D - Return line from a three hose fuel pump. If you don't want vapor lock issues you need to plumb this up.

You don't have to use the overcomplicated BS job GM came up with with forty lines attached to it. The 3 hose 1972 Corvette evap can is easy to plumb and it keeps the fuel vapor sequestered til you're driving so your garage doesn't smell like you have a gasoline leak. The purge valve vacuum actuator is connected to ported vacuum. The big fat vapor purge line is teed into the PCV hose with J30R7 fuel vapor line. It costs you nothing in performance to use one and it keeps SWMBO happy.
There are other GM rigs that use this can but that's the one I know has one.