Help with dual tank selector valve wiring

jseabolt · April 6, 2012

The work has finally begun! I dropped both fuel tanks yesterday and removed all the hoses to measure (roughly 9 feet for both) so I am halfway there. 1976 Chevy 454 big block with factory dual fuel tanks.

Has anyone ever replaced the OEM selector valve with one of those Pollak 6 port universal valves sold at autopart stores?

I broke one of the 1/4" return nipples on the selector valve (Dad wanted a new one anyway) and I am having trouble figuring out how to wire up this new selector valve I got from AutoZone. The instructions are horrible!

Here is how the OEM valve and switch are wired up. One wire goes to the selector valve. The valve grounds through the body. When the solenoid is energized it sends/recieves fuel to one tank and when de-energized it sends/recieves fuel to the other tank. The sending unit wires goto the switch and then to the fuel guage. Like this:

Using a switch that looks like this:

The new selector valve has five pins on it.

With this valve, based on what I can make from the directions, Pins A and C goto the sending units, B goes to the guage. So I shouldn't bother with those pins because the factory switch will take care of that.

So that leaves two connectors left.

From what I understand from the directions, it says pins D and E control the solenoid and by switching polarites will control which ports are open. With the valve "AS IS", two of the ports are already open. That that leads me to believe if I were to connect power to one pin (D or E) and ground the other (E or D), the valve should swap ports.

On the other hand, based on the schematic, there does not appear to be a ground connected to the connector. So perhaps the selector valve grounds through the mounting nuts like the OEM valve. And it's just a matter of connecting power to either the D or E pin to energize the selector valve.

I have yet to figure out which position sends power to the selector valve. I'll get out my test light to make sure.

While I am on the subject, there are three ports on the sending unit. 3/8" supply, 1/4" return and a 5/6" port with a 3" hose attached to it and a brownish valve of some sort at the end. Is this a redundant two way check valve to maintain atmospheric pressure in the tanks? This truck has no factory emmision other than a PVC valve so it appears the tank vent through the fuel caps. I thought about just capping these ports off with vinyl caps. Good or bad idea?

txab · April 6, 2012

Why didn't you purchase the OEM version. It only has one wire. Cost like $55 or less. Simple switch out. Takes 15 minutes

Edit: After you added the the first wiring diagram, you now know which electric ports you need to use. All you need is power and ground since the sending unit switching is handled at the selector switch. Do not cap off any tank vent lines

jseabolt · April 6, 2012

Why didn't you purchase the OEM version. It only has one wire. Cost like $55 or less. Simple switch out. Takes 15 minutes

Edit: After you added the the first wiring diagram, you now know which electric ports you need to use. All you need is power and ground since the sending unit switching is handled at the selector switch. Do not cap off any tank vent lines

Yeah that would have been my first choice if I could find one. I didn't try NAPA being they are on the other end of town.

I went to three auto part stores yesterday (O'Relieys, Advance and Autozone) and the six pin model was all they could get. Hell the first two stores were out of fuel line hose and clamps! They blamed it on lawnmowing season. I blame it on poor ordering and keeping inventories low to get bonus checks.

I was going to check with LMC but I'd really like to wrap this project up ASAP because the truck in out in the driveway blocking off one bay of my garage.

I didn't want to put the truck in the garage being it needs a paintjob anyway and it's hail season.

I still need to know if the selector valve grounds through the mounting holes or not. In other words I'd prefer not to fry this thing if possible. I could always take it back and say I changed my mind if I were to fry it.

jseabolt · April 15, 2012

I ended up ordering one off Amazon.com of all place for $64 including shipping. I painted the tops of the tanks with Rustoleum while I had them out from where the mulch had been sitting on top of the sending units for so long. This truck required a total of almost 20 feet of hose!

I still couldn't figure out where the fuel leaks were coming from. This truck would leak fuel from somewhere then onto the exhaust pipes!

I inspected the old hoses for cracks but couldn't find any. The hoses looked "bad" being almost 40 years old but not that bad. Unless there was a pinhole leak I couldn't find.

Now only the driveshaft carrier bearing!

Nobody answered my post concerning that. Does the driveshaft just slide out of the transmission? Like it would on a C4 Ford?