dual fuel tank hose routing

[73c201]

Hi I have a 1973 Chev C20 with dual tanks, it had a manual valve on the floor when I bought it and a fibreglass tank on one side, i have converted the tank to a steel factory type and have some electric parts from a 1976 and want to convert the 1973 to the electric type and wondering if anyone has a line routing diagram for this? (were the lines all rubber from the factory?)

thank you

[bnoon]

The majority of the length of fuel lines are steel with a few inches of rubber to connect to the junction at the switching unit and to the tank. At least on my '86.

For wiring I found this apparently for an '85


For the hoses it depends on which switching unit you're going with. The 3 port aftermarket ones I've seen only switch the feed side with no return ports being switched from tank to tank (I assume they'd just T-the returns to both tanks). The factory one on my '86 has 6 ports and switches the return line along with the feed from both tanks (two lines to the front, two lines left tank, two lines right tank). I'm not sure how you could do the 3 port one otherwise the return fuel flow would go to both tanks, at least in my mind. Not sure how that works or if it's even a problem to worry about.

[73c201]

thank you
also need the routing of the fuel lines- i am pretty sure the 1976 is the factory one-should i check it and see how many ports it has?

[hatzie]

That's the wiring diagram for the later motorized 1982-1986 system.

You can find the 1973 hose routing in Section 8 of the ST330-73 1973 Service Manual. It's around 45meg.
The 1973 Wiring Diagrams are around 7 meg.

ST_330_73_1973_Light_Truck_Service_Manual.pdf
X_7305_1973_GMC_Truck_Wiring_Manual_CK_10_30_Pgs_Only.pdf
ST_333_73_1973_Chevrolet_Passenger_Car_and_Light_Truck_Overhaul_Manual.pdf

[Tucson38]

What's the story with that manual valve? Was it a factory item or part of the fiberglass tank? I'd prefer a manual valve to the trouble-prone electric one.

[Firebirdjones]

Frankly I've never seen the manual valve and since the OP's added tank was also plastic, it sounds to me like it was all added at some point and not OEM. Might find some of your manual switches on bigger rigs though, but I wouldn't think so on a pedestrian truck.

I've never had any trouble with the factory electric setup on my 79. It's all still original 1979 issue and works like a champ. Although I do like the idea of the manual operation to simplify things.

[hatzie]

The only real trouble I've seen with these is the dash switch and once in a while the valve. The problems I've encountered with the rest of the system are from "repairs".

[73c201]

i don't think the fibreglass tank had a sender in it, but i just gave it away when i switched to the metal one,i know it was a huge tank- that was way back in 1983 or such when i first bought the truck, the valve was mounted on the floor just to the left of the seat. i could try and find it and send you a picture or something-- just got back around to trying to hook it up correctly. as i just found these parts from a 1976

[73c201]

thanks for the manual downloads !!!