duel fuel tank problem

[skeebo23]

hey guys, bought a 1987 chevy tbi, 350, swb
great truck has 97,000 orig miles and runs awesome!

problem is i cant get it to switch from passenger tank over to drivers side tank. When i switch in cab, it dies quickly.
I have replaced the in cab switch, as well as the fuel tank selector valve under the truck. i do not hear anything when switching over, nor does the gauge change. not sure how to troubleshoot!
thank you in advance for any suggestions or remedies.

[J Knight]

I think 87 tbi trucks have fuel pumps in the tank. Maybe the pump in left tank is bad. Maybe check plug conections on selector valve. Just some ideas.
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[skeebo23]

correct, problem is i cant get it to switch over to left tank at all. i just put new selector valve on, and all connections are good. Also replaced tank switch in cab as well.

[J Knight]

Maybe a bad wire between in cab switch and selector valve. What was happening before you changed parts?
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[skeebo23]

nothing, i changed the parts in hopes it would fix issue, i bought truck a few months ago, and drivers side tank was not working when i purchased ( i was told ), so this is what i have done so far in hopes to fix it.

[MadManAndrew]

As mentioned above, that only leaves the wires and the fuel pump. The truck dieing when you switch it over means that your passenger side pump is shutting off, and your valve is switching leaving you with no fuel if your driver side isn't coming on. Also, your truck probably will die if you switch it over with it running. You need to kill it, switch it over, then start it back up.
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[skeebo23]

i was under the impression that when you switched in cab to other tank, you would hear the selector valve. i am not hearing it at all, so i feel its not actually switching over to the tank, so i guess i need to check power to the valve and or ground?

[MadManAndrew]

I don't know if you'll be able to hear it or not, but if you think your problems with the valve, yeah, that'd be a good place to start. I would ask around or try to get my hands on a voltimeter in your case, it would make things a lot easier.
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[J Knight]

Not to sound insulting, but does the left tank have gas in it? I've seen the obvious overlooked more than once.
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[baclay9]

I can hear the valve changing sides clearly in mine. Also, you should be able to switch it over with the truck running without issue. I would start with the wireing to the selector valve.

[skeebo23]

thanks guys, will start to trace wires from in-dash switch back to selector valve, will update if i find anything

[J Knight]

I still think its the left tank fuel pump. Let us know what it was when you get it fixed.
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[skeebo23]

i will do, just something tells me something else, also when i do switch over to left tank, my gauge doesnt change either, so something doesnt seem right, but i have an extra fuel pump that works, its older, but works, so not too much trouble to test your theory, so will keep you posted!

[J Knight]

Uh oh, the gas gauge not working when you change to left tank changes everything. The selector valve makes the switch for the gauge. I would pull the fuel lines off of the valve that go to the left tank to see if fuel pump is working.
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[skeebo23]

yea i guess i forgot to mention that, i am not getting it to switch over at all at the selector valve, its brand new, as well as the dash switch, guess i'm going to have to do some electrical tracing now
UGH!

[J Knight]

This is going to be a puzzler!!!
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