Bench test tank selector valve?

[bnoon]

The passenger's side tank and lines have been removed from my truck by a previous owner and the selector valve has been bypassed. The selector valve ports have all been capped which leads me to believe that it may still work. Is there a way to test it besides just hooking it up? I'm going to have to clean it and get a wiring clip/pigtail to put it back in service anyway (as well as buying the tank/lines/etc), but I don't know how to test it.

[JCampbell]

Subscribed. I'd like to know this, too. Just pulled a solenoid off a parts truck I scrapped and I want to know if it's any good.

[Pyrotechnic]

Hook up some hose to the port(s) where fuel would enter. Blow into the lines and see which port the air comes out of when it's off. Hook up 12V. Blow into the line(s) again and note which port the air comes out of. The air should come out of different port(s) when 12V is applied.

For a 3 port model, fuel enters into a single port on one side and exits out of one of 2 ports on the other side.

6 port models switched over a return line as well as a supply line, so they are like two 3 port solenoids in one.

[INSIDIOUS '86]

Lol so wich ones flow the most fuel?
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[Pyrotechnic]

They both flow the same. The 6 port model has an extra set of 5/16 ports that can be used for a return/vent line.

The reason I mention the 6 port is because some parts catalogs specify a universal 6 port and note to cap off the un needed ports. Some trucks may be running around with style of selector valve, even if it was not original equipment.

Awhile back I was trying to find an original style 3 port and not having much luck. Found one through the GM parts system at another dealership and had it mailed to me.

[INSIDIOUS '86]

Hmm wonder how much hp we can support on the stock system. Fuel pump unincluded
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[hatzie]

There are two types.
Solenoid with a single + terminal that ground through the valve's metal body.
Motorized with a 6 position WeatherPak female connection.

I believe the OEM solenoid valves were 3 port units... They didn't have a return line connection. These valves have a "rest position" that they return to when power is removed.

• Hook a clean hose to the outlet port and blow through.
• Note which port on the other side the air came through.
• Apply Ground to the body and +12vdc hot to the stud.
• Blow again. Air should come from the other port. If it does the valve is switching.

The Motorized valves have 3 extra hose connections for return lines. Internally they're a bit more complex with 2 switches and a DC valve motor. The motor that drives the valve reverses depending on the position of a polarity-reversing dash switch. This valve doesn't have a "rest position" it stays wherever it was last switched.

Get a WeatherPak repair plug or pins to mate with this valve.
Starting at the fuel line end of the valve the connector is pinned as follows;
Main Sender, Fuel Gauge, AUX Sender, Motor, Motor, Unused. The motor leads are + or - depending on the position of the dash switch.

• Hook a clean hoses to the supply port and return port and blow through each. See the cutaway pic below.
• Note which ports on the other side the air came through.
• Set your meter to Ohms and touch the leads together to verify that it reads 0 ohms. Check which pins of the gauge switch are shorted. It'll be Main-Gauge or AUX-Gauge.
• Run the valve motor. It will automatically stop as the internal switching includes an end of travel switch.
  [**]Ground one Motor wire and 12vdc to the other Motor wire.
  [**]If the valve doesn't move or make noise swap ground and 12v pins. [**]If it still doesn't move the valve is dead.
• Blow again at each hose. Air should come from the other ports. If it does the valve is switching.
• Set your meter to Ohms and touch the leads together to verify that it's still reading 0 ohms. Check the sender to gauge is switching. ex. if your first test showed AUX to Gauge shorted it should now show Main to Gauge shorted.

The only other test you can run on either is a leak test at 7-12 psi. higher pressure can rupture the body or internal seals.

[bnoon]

Thanks for the ideas. I'm going to pull the valve off tonight (mine is motorized 6 port) and test it maybe Thursday night.

[Desert1957]

Originally Posted by hatzie

There are two types.
Solenoid with a single + terminal that ground through the valve's metal body.
Motorized with a 6 position WeatherPak female connection.

I believe the OEM solenoid valves were 3 port units... They didn't have a return line connection. These valves have a "rest position" that they return to when power is removed.

• Hook a clean hose to the outlet port and blow through.
• Note which port on the other side the air came through.
• Apply Ground to the body and +12vdc hot to the stud.
• Blow again. Air should come from the other port. If it does the valve is switching.

The Motorized valves have 3 extra hose connections for return lines. Internally they're a bit more complex with 2 switches and a DC valve motor. The motor that drives the valve reverses depending on the position of a polarity-reversing dash switch. This valve doesn't have a "rest position" it stays wherever it was last switched.

Get a WeatherPak repair plug or pins to mate with this valve.
Starting at the fuel line end of the valve the connector is pinned as follows;
Main Sender, Fuel Gauge, AUX Sender, Motor, Motor, Unused. The motor leads are + or - depending on the position of the dash switch.

• Hook a clean hoses to the supply port and return port and blow through each. See the cutaway pic below.
• Note which ports on the other side the air came through.
• Set your meter to Ohms and touch the leads together to verify that it reads 0 ohms. Check which pins of the gauge switch are shorted. It'll be Main-Gauge or AUX-Gauge.
• Run the valve motor. It will automatically stop as the internal switching includes an end of travel switch.
  [**]Ground one Motor wire and 12vdc to the other Motor wire.
  [**]If the valve doesn't move or make noise swap ground and 12v pins. [**]If it still doesn't move the valve is dead.
• Blow again at each hose. Air should come from the other ports. If it does the valve is switching.
• Set your meter to Ohms and touch the leads together to verify that it's still reading 0 ohms. Check the sender to gauge is switching. ex. if your first test showed AUX to Gauge shorted it should now show Main to Gauge shorted.

The only other test you can run on either is a leak test at 7-12 psi. higher pressure can rupture the body or internal seals.

Hey Hatzie,

Great pic of the Selector valve.

Desert

[hatzie]

Originally Posted by Desert1957

Hey Hatzie,

Great pic of the Selector valve.

Desert

I found that cutaway picture of the motorized valve a long time ago. I've forgotten where I found it. Maybe directly from Pollack??? A lot of the documentation that used to be on their site is gone.

I keep intending to do a write-up on the GM dual tank valve & gauge switching systems. Even the motorized valves aren't that complicated once you know how they work.