Bad Fuel Tank Selector Valve?

[Chevyguy]

Hey guy's

I'm a new member and I've got a 1987 V-20 with a 5.7 and TBI. I just replaced the fuel pump and strainer in the drivers side tank. After I put fuel in the tank I flipped the tank switch from the right to the left tank and started it. It ran rough for a little bit but it smoothed out after I let it run. My problem is when it's running on the drivers side tank all the fuel in the tank flows to the passenger side tank. I'm thinking something might have gotten stuck in the tank selector valve and it's not completely switching over and it's sending the fuel over to the other tank. What do you guy's think?.

Regards.
Clayton

 

[bucket]

Sounds like that's it, unless somebody has monkeyed with the return lines.

 

[Chevyguy]

I replaced the rubber lines at the tank and I made sure they were all connected properly to the sending unit. Is it possible to flush out the selector valve?. I might have a piece of dirt or something making it not function properly.

Clayton

 

[hootsmcgoots]

Sounds like that's it, unless somebody has monkeyed with the return lines.

X2. Sounds like return lines may be reversed.

Sent from my SAMSUNG-SGH-I847 using Tapatalk 2

 

[Chevyguy]

I put the new lines on the way the old ones came off. I lengthened them to make it easier to reconnect them. When the original ones were installed the bed was off the truck. And I used Rubber fuel injection line. I wonder if I sucked a piece of dirt into the switch valve.

Clayton

 

[78 Chevyrado]

That sounds like when my valve failed. Why it flowed from one tank to the other was that the valve had hung in between LEFT and RIGHT. I thought for 4 days somebody was stealing my gas, till i checked the other tank and it was almost full.

Sounds like your valve has given up the ghost.

 

[Chevyguy]

That sounds like when my valve failed. Why it flowed from one tank to the other was that the valve had hung in between LEFT and RIGHT. I thought for 4 days somebody was stealing my gas, till i checked the other tank and it was almost full.

Sounds like your valve has given up the ghost.

Thanks Kenny, It's kind of weird that the valve would go out after I replaced the pump. But then again I've only been running off the other tank for the past year and the truck has sat alot. In other words I haven't been switching back and forth between the two tanks. Which valve did you have, the 3 or the 5 port?. I still need to remove a metal shield so that I can see which valve my 87 has. From what I've read it probably has the 5 port valve since I have TBI. And of course thats the expensive one.

Clayton

 

[oneluckypops]

Thanks Kenny, It's kind of weird that the valve would go out after I replaced the pump. But then again I've only been running off the other tank for the past year and the truck has sat alot. In other words I haven't been switching back and forth between the two tanks. Which valve did you have, the 3 or the 5 port?. I still need to remove a metal shield so that I can see which valve my 87 has. From what I've read it probably has the 5 port valve since I have TBI. And of course thats the expensive one.

Clayton

This confuses me. Damn I really need to pay more attention to older trucks.
Correct me if I am wrong here but each tank should have a pressure line and a Return line that connects to the switching valve correct? That would already be 4 ports on the valve, Now on the outlet side of the valve I would think you should have a Pressure line and a Return line, which would make it a 6 port Valve correct?

In any case you should be able to leave the elctrical connector plugged in and unhook all the lines from the valve. Blow in the INLET side of the valve on both the pressure ports and the return lines, You should be able to feel air coming out of the OUTLET side pressure and return ports depending on which side your blowing thru at the time. Then blow in the RETURN side port on the OUTLET side of the valve, and see if you can feel air on BOTH return ports leading back to the tank. Chances are the valve is stuck on the return side and your gas is returning to the wrong tank.

a 3 port valve would be for an older chevy which uses NO return lines/ 1 line from PS tank to valve, 1 line from DS tank to valve, then 1 line from valve to fuel pump Correct?

a 5 Port valve would be of course 1 pressure line from each tank to valve, then 1 pressure line from valve to pump correct? How exactly would the Return lines be set up then? You have to have a return from the pump back to the valve, then from the valve to each tank right?

 

[oneluckypops]

I think if It was me I would install inline filters before the valve on each pressure line, that would prevent any dirt from entering the valve in the future

 

[Chevyguy]

I think if It was me I would install inline filters before the valve on each pressure line, that would prevent any dirt from entering the valve in the future

This is a great idea, I probably sucked a piece of dirt into the valve when I switched to the tank that I put the new pump in. The tank itself was clean and I drained it completely of any old fuel. I'm going to try to make some time today to go underneath and see which valve I have. Thanks Luke.

Clayton

 

[Chevyguy]

Looks like I've got a six port valve. Anybody know how the fuel lines are ran for an 87 as to diffrerentiate between the two tanks at the four port connection at the back of the valve. I want to see if I've got my lines hooked up properly at my fuel pump. If not I can just switch em at the valve. I'm going to disconnect the lines at the back of the valve and see which ones pushing fuel when the left tank pump is energized. If it's coming out the correct side I'll know my valve is bad.

Clayton

 

[Jims86]

Looks like I've got a six port valve. Anybody know how the fuel lines are ran for an 87 as to diffrerentiate between the two tanks at the four port connection at the back of the valve. I want to see if I've got my lines hooked up properly at my fuel pump. If not I can just switch em at the valve. I'm going to disconnect the lines at the back of the valve and see which ones pushing fuel when the left tank pump is energized. If it's coming out the correct side I'll know my valve is bad.

Clayton

The return line diameter should be smaller than the supply line. I agree with OLP on the pre filters. I would grab a few more of the same filter thats on your truck now, and get some barbed fittings and clamps, and splice them in.

 

[Chevyguy]

The return line diameter should be smaller than the supply line. I agree with OLP on the pre filters. I would grab a few more of the same filter thats on your truck now, and get some barbed fittings and clamps, and splice them in.

Only fuel filter I have is the metal one thats after the switch valve. You know the one with the factory plumbed threaded fitted lines. I'll look into plumbing in some filters before the valve. I might have gotten the lines crossed at the pump. All I had for replacement line at the time was the larger supply line diameter size. It's double clamped and definately not leaking. I know I should have gotten the smaller sized line but at the time I wasn't close to town.

Clayton

 

[Chevyguy]

I just recieved my 1986-1987 Chevy Light Duty Shop And Overhaul Manuals CD. It includes the 86 Shop, and wiring diagram manuals, the 87 Shop, and Fuel and Emissions Manual, and the 87 Overhaul Manual. It's nice, I've got a great diagram that shows all the lines going into the selector valve. Gonna probably order a valve today so that I can install it next week. This CD was well worth the $25 I paid for it.

Clayton

 

[Chevyguy]

The switching valve arrived this afternoon when I was out running down a job lead and of course it was signature delivery confirmation. So I get to go to the post office tomorrow morning. Fedex just dropped off my right outer tie rod from Rock Auto this morning. Wish the mailman coulda done that. It's raining now too, gonna be fun tomorrow.

Clayton