How do I use the tank selector on 1973 Camper Special

[Moms1973K20]

Sorry to barge in on this thread but I'm am about to embark on a similar issue.
My wifes 73 has 2 tanks. Has the switch on the dash and a solenoid valve down on the frame.
Its the 3 port valve which has to be 1 port from each tank and 1 to the pump.
The Switch on the dash is what switches the sending unit signals to the gauge correct ?
So when power is applied to the solenoid valve it switches from right to left ? (Its running off the left tank now and the gauge doesn't work).
I need to make sure the valve is bypassed (which I think it is) and then check power to and from the switch and down to the valve.
Should be Left tank first and then switch to right hand tank once the left is empty ? I want to make sure I hook it all back up correctly.

 

[SirRobyn0]

Sorry to barge in on this thread but I'm am about to embark on a similar issue.
My wifes 73 has 2 tanks. Has the switch on the dash and a solenoid valve down on the frame.
Its the 3 port valve which has to be 1 port from each tank and 1 to the pump.
The Switch on the dash is what switches the sending unit signals to the gauge correct ?
So when power is applied to the solenoid valve it switches from right to left ? (Its running off the left tank now and the gauge doesn't work).
I need to make sure the valve is bypassed (which I think it is) and then check power to and from the switch and down to the valve.
Should be Left tank first and then switch to right hand tank once the left is empty ? I want to make sure I hook it all back up correctly.

Rick, if it is still running the stock one wire valve under the truck then the gauge change over is a function of the dash switch. IIRC, no power to the valve will have it draw off the left tank, power to the valve switches it to the right tank. So in that setup it is possible for the gauge to read the amount in the wrong tank, for example the valve fails. It's stuck on the left tank but you hit the switch and since the switch is still working it changes the gauge to read the right tank so you keep driving until the left tank is empty and run out of gas in that tank.

Later on GM went to a valve with multiple wires running to it 6 I think. In that configuration, the valve is powered in a each direction, and the gauge change over is part of the valve so it will only change if the valve does in fact switch. Also those later valves were MUCH more reliable. At the shop we very much prefer to convert a truck to the 6 wire valve, vs troubleshooting the one wire valves, but the one wire valves and switches are still available, and certainly it is easier to just replace a valve vs reworking the entire system.

 

[idahovette]

In 73 the main tank should have been the right(passenger) side tank. I would think that there would be no power to that tank as it was the only tank on the truck unless you ordered it with the auxiliary(left/drivers) side tank?.........I'm old and I may be wrong

 

[SirRobyn0]

In 73 the main tank should have been the right(passenger) side tank. I would think that there would be no power to that tank as it was the only tank on the truck unless you ordered it with the auxiliary(left/drivers) side tank?.........I'm old and I may be wrong

I think Perry is right about this. When I was typing last night I was thinking the left tank was the main tank forgetting that the earlier trucks were visa versa.

 

[Moms1973K20]

Rick, if it is still running the stock one wire valve under the truck then the gauge change over is a function of the dash switch. IIRC, no power to the valve will have it draw off the left tank, power to the valve switches it to the right tank. So in that setup it is possible for the gauge to read the amount in the wrong tank, for example the valve fails. It's stuck on the left tank but you hit the switch and since the switch is still working it changes the gauge to read the right tank so you keep driving until the left tank is empty and run out of gas in that tank.

Later on GM went to a valve with multiple wires running to it 6 I think. In that configuration, the valve is powered in a each direction, and the gauge change over is part of the valve so it will only change if the valve does in fact switch. Also those later valves were MUCH more reliable. At the shop we very much prefer to convert a truck to the 6 wire valve, vs troubleshooting the one wire valves, but the one wire valves and switches are still available, and certainly it is easier to just replace a valve vs reworking the entire system.

Thank you for the reply. I "think" this how it works as well. My wife is excited to get both tanks going and the fuel gauge working as it should be. Its actually running off the driver tank now and the right side tank is just hanging there with no hoses attached . I am going to pull it down and clean it out and put some pressure to it and make sure I cant find any leaks. Then new hoses and reattach it and hook it all up the way it should be. I think I'll put a new switch and valve in for the best odds of success.

 

[SirRobyn0]

Thank you for the reply. I "think" this how it works as well. My wife is excited to get both tanks going and the fuel gauge working as it should be. Its actually running off the driver tank now and the right side tank is just hanging there with no hoses attached . I am going to pull it down and clean it out and put some pressure to it and make sure I cant find any leaks. Then new hoses and reattach it and hook it all up the way it should be. I think I'll put a new switch and valve in for the best odds of success.

If you find anything wrong with the tank, sending unit or sock, remember all that stuff is still readily available. A new tank is only about $100. For me at least if I was going though the work to remove a tank and clean it, I would want to put a new sending unit in it as it will come with a new seal and sock (the in tank pre-filter). After 40 years you can bet that sock is done, and it's really not worth it to try to run without it, as the tank valve really needs the in tank socks to be there.

I can understand wife's excitement. My truck was a single 20 gallon tank (drivers side for my year). And it just didn't work well for me. If I used it only for my commute to the shop I had to fill up twice a week pretty much. I generally like to fill around a 1/4 tank leaving some reserve. I could live with that, but I use my truck to haul feed for the farm and some of those trips are 200 - 300 miles round trip. If I didn't want to have a truck with no gas in it, I'd have to fill it on the way out and the way back home. Towing my 18' trailer was worse. So now I have 2 - 20 gallon tanks, so my system is fill them both, hammer the left tank on E then fill both when the right one is about 1/4. Much better range that way.

 

[Moms1973K20]

If you find anything wrong with the tank, sending unit or sock, remember all that stuff is still readily available. A new tank is only about $100. For me at least if I was going though the work to remove a tank and clean it, I would want to put a new sending unit in it as it will come with a new seal and sock (the in tank pre-filter). After 40 years you can bet that sock is done, and it's really not worth it to try to run without it, as the tank valve really needs the in tank socks to be there.

I can understand wife's excitement. My truck was a single 20 gallon tank (drivers side for my year). And it just didn't work well for me. If I used it only for my commute to the shop I had to fill up twice a week pretty much. I generally like to fill around a 1/4 tank leaving some reserve. I could live with that, but I use my truck to haul feed for the farm and some of those trips are 200 - 300 miles round trip. If I didn't want to have a truck with no gas in it, I'd have to fill it on the way out and the way back home. Towing my 18' trailer was worse. So now I have 2 - 20 gallon tanks, so my system is fill them both, hammer the left tank on E then fill both when the right one is about 1/4. Much better range that way.

Thank you for the info on availability. I am very pleasantly surprised buy the parts support for these trucks. I will most definitely be replacing the sending units as well and a new selector valve and dash switch. I want the truck as reliable as possible since my wife and daughter will be riding around in it.

 

[SirRobyn0]

Thank you for the info on availability. I am very pleasantly surprised buy the parts support for these trucks. I will most definitely be replacing the sending units as well and a new selector valve and dash switch. I want the truck as reliable as possible since my wife and daughter will be riding around in it.

I know what you mean, I regularly take my truck 200 miles from home, need it to be reliable!