Dual tank switch kills the engine

[shinkle]

I have a dual tank 87 R10. The truck runs great on the driver side tank. The gauge on the driver side works. When I flip the switch to change to the passenger tank the truck instantly dies. I replaced the switch and put gas in the passenger tank with no luck.

I'm no mechanic but can do easy direct replacement jobs.

Any suggestions?

 

[Grit dog]

Instantly like you turned off the ignition or like it doesn’t switch over and runs out of gas?
I can’t think of how the tank selector valve could possibly affect power to the ignition, save for some very “custom” wiring? And at that can’t even imagine why.

meaning it’s a great chance the valve just isn’t switching over.

 

[AKguy]

Those equipped with elecric fuel pumps?

 

[AuroraGirl]

can it be started with the tank switched and then key on, like you hear the pump whirr and everything?

 

[AuroraGirl]

all i can think is some weird scenario where its grounding your always live power and pulls down enough that your ignition cant operate, but im not sure how that works or would work. a severe case of EMI maybe

 

[gotyourgoat]

DOA switch? fuel pump not working?

Does the tank switch control power distribution to the fuel pumps in the dual tank fuel injected trucks? Or are they both powered via key on?

 

[shinkle]

Thanks all. The truck is all stock, no weird wiring. The engine dies instantly, not sputtering like out of gas. It dies almost faster than turning off the ignition. The switch is a simple switch, not one of those you have to depress and hold during change over. I bought the truck from original owner estate sale about 9 months ago. The passenger tank has never worked while I have owned it. It wont start with the tank switched over to passenger prior to starting. Not sure I hear the whrrrr.

 

[eskimomann209]

Thanks all. The truck is all stock, no weird wiring. The engine dies instantly, not sputtering like out of gas. It dies almost faster than turning off the ignition. The switch is a simple switch, not one of those you have to depress and hold during change over. I bought the truck from original owner estate sale about 9 months ago. The passenger tank has never worked while I have owned it. It wont start with the tank switched over to passenger prior to starting. Not sure I hear the whrrrr.

Just to double check. Engine shut off or total power?
Fuel injected or mechanical pump?

87 I’m pretty sure has an in tank fuel pump

 

[86454k30]

You have a bad fuel pump in the tank that kills the truck.

 

[75gmck25]

Carburetors have float bowls, so the engine dies very slowly when you cut off fuel. Most EFI systems maintain constant residual pressure so they can “shoot” fuel into the cylinder when needed. My guess is that the pump is bad on that side, or maybe the switch is not providing power to the pump.

I don’t have EFI, but on earlier trucks the tank switch wiring runs down inside the passenger side frame rail to the solenoid. There are junctions in the wires and the large plug on the solenoid, so you should be able to find test points and verify that the dash switch is providing power to the pump.

If somebody has mucked with the dash switch it also may be as simple as getting the correct switch. I think there are at least 3 different versions of the switch, so the exact year may matter.

 

[SquareRoot]

Carburetors have float bowls, so the engine dies very slowly when you cut off fuel. Most EFI systems maintain constant residual pressure so they can “shoot” fuel into the cylinder when needed. My guess is that the pump is bad on that side, or maybe the switch is not providing power to the pump.

I don’t have EFI, but on earlier trucks the tank switch wiring runs down inside the passenger side frame rail to the solenoid. There are junctions in the wires and the large plug on the solenoid, so you should be able to find test points and verify that the dash switch is providing power to the pump.

If somebody has mucked with the dash switch it also may be as simple as getting the correct switch. I think there are at least 3 different versions of the switch, so the exact year may matter.

This. Killing an efi pump kills the engine instantly.

 

[82sbshortbed]

If it fires up fine and runs good with the switch in the other position, I'd leave like that an use it as a anti theft device.

 

[shinkle]

Engine won't start with the switch on passenger side. I don't hear a click and whirrrr when the switch is on the passenger side and I turn the key. I can definietly hear the click and whrrrr on good driver side. I replaced the switch but I guess there is a chance I got the wrong part, but it was a simple plug and play.

 

[eskimomann209]

Engine won't start with the switch on passenger side. I don't hear a click and whirrrr when the switch is on the passenger side and I turn the key. I can definietly hear the click and whrrrr on good driver side. I replaced the switch but I guess there is a chance I got the wrong part, but it was a simple plug and play.

Above responded most likely bad fuel pump.
But above also mentioned good TS steps.
you will waste a lot of money buy just buying parts, finding out it doesn’t work then asking for the next “possible” bad part.
I, for one, will ask as many questions to get the total over view before making assumptions as to your problem.
But as mentioned above. Switch to the side that’s bad go down to the fuel selector valve unplug it and look for power on the plug going to the tank in question. mid power is present
Drop the tank inspect wiring, from selector plug to top of pump. If it looks ok pull the pump replace it.

 

[84K30]

For what it’s worth, my truck does not have electric pumps and would slowly die, as a result of being starved of fuel, when switched to the passenger tank. The issue ended up being a shorted out diverted valve. Your issue seems to be different though.