Dual tank solenoid valve

[tophat36]

I noticed an unplugged connector on my dual tank solenoid valve setup and plugged it in. Next day my truck wouldn’t start. Is this due to it not being properly grounded? 1980 gmc c2500

 

[Ricko1966]

Do both tanks have adequate fuel. You may have switched to an empty tank.

 

[tophat36]

Do both yanks have adequate fuel. You may have switched to sn empty tank.

That is an interesting thought… But that connector has been disconnected the entire time I’ve had the truck. In the cab when I switch it from left-hand to right hand tank, the fuel level drops to zero because that tank is empty and unused my neighborhood I bought it from said something happened to that tank or nothing really specific but that I shouldn’t use that side so I’ve never used it but I do know that when I switch from LH to RH that the switching function appears to work. Also, when the car wouldn’t start, it wasn’t for lack of fuel. It literally didn’t make any noise just a short click. I also checked the battery voltage and it was clearly dead.

 

[Ricko1966]

That is an interesting thought… But that connector has been disconnected the entire time I’ve had the truck. In the cab when I switch it from left-hand to right hand tank, the fuel level drops to zero because that tank is empty and unused my neighborhood I bought it from said something happened to that tank or nothing really specific but that I shouldn’t use that side so I’ve never used it but I do know that when I switch from LH to RH that the switching function appears to work. Also, when the car wouldn’t start, it wasn’t for lack of fuel. It literally didn’t make any noise just a short click. I also checked the battery voltage and it was clearly dead.

The dead battery,and truck doesn't crank would have been good info to put In post #1. Disconnect what ever you connected and charge the battery. Are any lights on? Radio,Etc.Then try to start the truck,does it start. Now take off the negative battery cable, hook a test light from the battery negative post,to the negative battery cable,does your test light light? If so you have a draw if not plug that connector back in,does the light light? There is a draw. That connector is most likely what switches your tanks,so flipping the switch does nothing because the wires are going to nothing.

 

[tophat36]

The dead battery,and truck doesn't crank would have been good info to put In post #1. Disconnect what ever you connected and charge the battery. Are any lights on? Radio,Etc.Then try to start the truck,does it start. Now take off the negative battery cable, hook a test light from the battery negative post,to the negative battery cable,does your test light light? If so you have a draw if not plug that connector back in,does the light light? There is a draw. That connector is most likely what switches your tanks,so flipping the switch does nothing because the wires are going to nothing.

What part of truck wouldn’t start doesn’t tell you the battery is dead? I didn’t realize that wasn’t clear, my apologies. Yes, truck wouldn’t start bc that connection I made somehow drained the battery. Truck didn’t turn over or try it.

 

[Ricko1966]

What part of truck wouldn’t start doesn’t tell you the battery is dead? I didn’t realize that wasn’t clear, my apologies. Yes, truck wouldn’t start bc that connection I made somehow drained the battery. Truck didn’t turn over or try it.

Truck doesn't start and truck doesn't crank are completely different to me. Good luck. If the truck doesn't have gas will it start? Will it crank? If the truck doesn't have spark,will it start? Will it crank? Etc. Etc. Lots of things keep a truck from starting besides dead batteries. My first assumption was you hooked up the tank switching valve and accidently switched to a dry tank. Truck wouldn’t start due to no fuel. They won't start with out fuel,even with a good battery.

 

[tophat36]

Truck doesn't start and truck doesn't crank are completely different to me. Good luck. If the truck doesn't have gas will it start? Will it crank? If the truck doesn't have spark,will it start? Will it crank? Etc. Etc. Lots of things keep a truck from starting besides dead batteries. My first assumption was you hooked up the tank switching valve and accidently switched to a dry tank. Truck wouldn’t start due to no fuel. They won't start with out fuel,even with a good battery.

Yeah I understand the confusion I just think a truck would actually start even if switched to an empty tank bc there may still be some fuel present. It would die but possibly start, sorry for the assumptions. I’ll see if it starts when I get home and see if the saga continues! Thank you for ur help.

 

[tophat36]

The dead battery,and truck doesn't crank would have been good info to put In post #1. Disconnect what ever you connected and charge the battery. Are any lights on? Radio,Etc.Then try to start the truck,does it start. Now take off the negative battery cable, hook a test light from the battery negative post,to the negative battery cable,does your test light light? If so you have a draw if not plug that connector back in,does the light light? There is a draw. That connector is most likely what switches your tanks,so flipping the switch does nothing because the wires are going to nothing.

Truck started with no connector. I switched the in cab switch to RH and it dropped to empty but continued to run. Switched it back to LH and no change. Looked at the valve under car and 4 of the 6 hoses are capped. Only 2 hoses go anywhere. I’m assuming this means that tank isn’t connected at all?

 

[ali_c20]

Truck started with no connector. I switched the in cab switch to RH and it dropped to empty but continued to run. Switched it back to LH and no change. Looked at the valve under car and 4 of the 6 hoses are capped. Only 2 hoses go anywhere. I’m assuming this means that tank isn’t connected at all?

Post a pic of the valve. The valve can be used with or without return. When used w/o return the return ports (5/16) can be capped off. Maybe it's time to get a new valve?

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[tophat36]

Post a pic of the valve. The valve can be used with or without return. When used w/o return the return ports (5/16) can be capped off. Maybe it's time to get a new valve?

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If u can tell me how the 6 lines are supposed to be I can tell you what’s different. 4 of the 6 ports on my valve assembly are capped. Mine is the same as this picture. The only 2 lines that are connected from this valve assembly go to the RH tank I don’t use. Each sending unit has 3 hoses connected at each tank. The vent line is connected at my charcoal canister. No lines going to the LH tank go thru this valve.

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[AuroraGirl]

If u can tell me how the 6 lines are supposed to be I can tell you what’s different. 4 of the 6 ports on my valve assembly are capped. Mine is the same as this picture. The only 2 lines that are connected from this valve assembly go to the RH tank I don’t use. Each sending unit has 3 hoses connected at each tank. The vent line is connected at my charcoal canister. No lines going to the LH tank go thru this valve.

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They dont make these anymore.
Your truck , if it has the 1980 column and fuse box , has a fuel switching module on it that prevents the tank solenoid from operating when you turn your vehicle on under certain circumstances, because everytime the key was turned in the old days, the solenoid would cycle, which is what lead to them dying early deaths. There is still 3 port solenoids produced, and you can wire 2 of them to work.... but being they live short lives, the motorized valve is the answer

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It means your valve has already been bypassed, your tank that is still hooked up was not unhooked since the tank wasnt working for whatever reason (dirty tank sock, leak, full of debris, etc)
The switching the tank with the switch is only switching the gauge over.

You can put a 6 port MOTORIZED which is what ali showed:

Post a pic of the valve. The valve can be used with or without return. When used w/o return the return ports (5/16) can be capped off. Maybe it's time to get a new valve?

You must be registered for see images attach

 

[tophat36]

They dont make these anymore.
Your truck , if it has the 1980 column and fuse box , has a fuel switching module on it that prevents the tank solenoid from operating when you turn your vehicle on under certain circumstances, because everytime the key was turned in the old days, the solenoid would cycle, which is what lead to them dying early deaths. There is still 3 port solenoids produced, and you can wire 2 of them to work.... but being they live short lives, the motorized valve is the answer

You must be registered for see images attach

It means your valve has already been bypassed, your tank that is still hooked up was not unhooked since the tank wasnt working for whatever reason (dirty tank sock, leak, full of debris, etc)
The switching the tank with the switch is only switching the gauge over.

You can put a 6 port MOTORIZED which is what ali showed:

Thank you! Yeah I had stumbled on a lot of videos and posts about them not being produced anymore, pretty silly but at least there’s a solution. I work with solenoid valves a lot; they can be pretty robust but not for 40 years. Honestly I don’t think I need 2 gas tanks but bc it was standard I will probably just retire the RH one in place. It does also give me the option to drop it first and replace it, get that all cleaned up and then address the SV and other tank later.

The information I’m trying understand is what lines are supposed to come in and go out of tbat assembly…essentially all of the flow paths and direction of flow bc the shop manual is surprisingly vague.

If there are 3 lines that go to each tank (vent, supply, return), vent does not go thru the valve right….it just comes from the canister in engine bay? Is that the line that tees off to each tank by the valve?

If you have a supply line coming out of each tank into the valve, valve determines which tank to pull fuel from and that goes to the engine/carb?

The return line would also come out of each tank and thru the valve. From there where does that connect? Outlet of carb or engine somehwhere? Manual says it’s to prevent vapor lock…is that vapor lock in the pump or the tank? If the tank is vented I don’t know how that could happen, but maybe it’s the pump they’re talking about? Also what’s the concern with vapor lock, like what happens if that occurs?

Last thing, my LH sending unit has a torn hose, completely severed. It appears to be the middle line. I know it’s not the supply, but I feel like the truck is super smelly. Is there a way to tell if it’s the return or vent? The truck seems extra smelly, I know that’s how carbureted vehicles are but this is extra. Wonder if I fix that hose if it will reduce what I smell. Do fuel hardlines need to be replaced like brake lines do?


Thank you everyone for your help as always! I took many pictures of that darn valve but bc it’s bypassed mostly, it’s hard to see anything.

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[AuroraGirl]

Thank you! Yeah I had stumbled on a lot of videos and posts about them not being produced anymore, pretty silly but at least there’s a solution. I work with solenoid valves a lot; they can be pretty robust but not for 40 years. Honestly I don’t think I need 2 gas tanks but bc it was standard I will probably just retire the RH one in place. It does also give me the option to drop it first and replace it, get that all cleaned up and then address the SV and other tank later.

The information I’m trying understand is what lines are supposed to come in and go out of tbat assembly…essentially all of the flow paths and direction of flow bc the shop manual is surprisingly vague.

If there are 3 lines that go to each tank (vent, supply, return), vent does not go thru the valve right….it just comes from the canister in engine bay? Is that the line that tees off to each tank by the valve?

If you have a supply line coming out of each tank into the valve, valve determines which tank to pull fuel from and that goes to the engine/carb?

The return line would also come out of each tank and thru the valve. From there where does that connect? Outlet of carb or engine somehwhere? Manual says it’s to prevent vapor lock…is that vapor lock in the pump or the tank? If the tank is vented I don’t know how that could happen, but maybe it’s the pump they’re talking about? Also what’s the concern with vapor lock, like what happens if that occurs?

Last thing, my LH sending unit has a torn hose, completely severed. It appears to be the middle line. I know it’s not the supply, but I feel like the truck is super smelly. Is there a way to tell if it’s the return or vent? The truck seems extra smelly, I know that’s how carbureted vehicles are but this is extra. Wonder if I fix that hose if it will reduce what I smell. Do fuel hardlines need to be replaced like brake lines do?


Thank you everyone for your help as always! I took many pictures of that darn valve but bc it’s bypassed mostly, it’s hard to see anything.

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im surprised your engine has a canister. do you have a VECI underhood on your air cleaner or your core support?

Thats Vehicle Emissions Control Information

Will have your vacuum routing and stuff probably on it ,and state what emissions your vehicle is compliant to

And does that mean your truck had a LE9 or LT9?

 

[AuroraGirl]

Thank you! Yeah I had stumbled on a lot of videos and posts about them not being produced anymore, pretty silly but at least there’s a solution. I work with solenoid valves a lot; they can be pretty robust but not for 40 years. Honestly I don’t think I need 2 gas tanks but bc it was standard I will probably just retire the RH one in place. It does also give me the option to drop it first and replace it, get that all cleaned up and then address the SV and other tank later.

The information I’m trying understand is what lines are supposed to come in and go out of tbat assembly…essentially all of the flow paths and direction of flow bc the shop manual is surprisingly vague.

If there are 3 lines that go to each tank (vent, supply, return), vent does not go thru the valve right….it just comes from the canister in engine bay? Is that the line that tees off to each tank by the valve?

If you have a supply line coming out of each tank into the valve, valve determines which tank to pull fuel from and that goes to the engine/carb?

The return line would also come out of each tank and thru the valve. From there where does that connect? Outlet of carb or engine somehwhere? Manual says it’s to prevent vapor lock…is that vapor lock in the pump or the tank? If the tank is vented I don’t know how that could happen, but maybe it’s the pump they’re talking about? Also what’s the concern with vapor lock, like what happens if that occurs?

Last thing, my LH sending unit has a torn hose, completely severed. It appears to be the middle line. I know it’s not the supply, but I feel like the truck is super smelly. Is there a way to tell if it’s the return or vent? The truck seems extra smelly, I know that’s how carbureted vehicles are but this is extra. Wonder if I fix that hose if it will reduce what I smell. Do fuel hardlines need to be replaced like brake lines do?


Thank you everyone for your help as always! I took many pictures of that darn valve but bc it’s bypassed mostly, it’s hard to see anything.

You must be registered for see images attach

the lines would have met under the cab for the valve , only one set of fuel and return would go up to the fuel pump
the vent was most likely tied to each tank then your canister, unless your truck didnt have a canister originally (then it would be vented at the tank and you would have gas caps with a hole in them)

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This would be the vented gas cap 1980

 

[AuroraGirl]

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SMallest line is vent, next biggest is return. largest is supply

The vent on mine goes a short distance to a vent that looks like an axle vent