Dual fuel tank will not switch over

is their duel fuel pumps? one may be failing, two filters?one may be clogged. chevy truck forum will tell, Im not a mechanic of vehicles but take a few wild stabs in the dark. and really hit pay dirt it seems. Oh another thing the diverter valve may not be slamming the slammer causing restriction !

Thank you! I haven't really looked because wasn't sure where to start. At least now I can at least check into all that you described. Again much thanks!

on cars that I have seen have a handle to flip the connection (pulling gas into the passenger compartment) probably that's why we keep this business out of your footwell these days~

It could be the dash switch, but most likely the switching valve under the truck. If you follow the fuel lines from each tank, the lines join together at a silver valve bolted to the frame. These can be purchased at O'reilly, Pep Boys, etc.

I have almost the same problem with my 85 truck. I can drive it a couple of days, then the next day it won't start. If I toggle the switch back and for then I can sometimes get it to start.

Don't no

check for a clog in the sending unit in the left tank. even if the right tank is empty, that system is supposed to pull the fuel from the left tank automatically. when I bought my '86 c20 454ci with the dual tanks, the truck's gas gauges didn't work and I didn't know it, but the right tank was empty and the system was pulling from the left tank when the right tank was empty.

I'm having same issue. It started with happening with one tank. Then two weeks later the other tank is not getting fuel now. Can't start it at all now.

Fuel filter or fuel pump if you can't draw from either side.

I changed deverter valve and still no fuel from right tank

It is the little (and easy to change) electric switch in the cab and most likely not the diverter valve (I was told that was the problem with my truck, so I changed it and my truck - 85 K20 Long Bed had the same problem as before.) I changed the little electric toggle switch (the one you press to switch tanks) and mine worked perfectly after that. Spoke with other Chevy/GMC truck owners with dual tanks and to the person it was the littlhe toggle switch with theirs as well. Just saying.

I have the switch and out of gas in my driveway the right tank was empty and the left tank was full and would not start until I add gas to the right tank.

check fuse

First check the fuse, then make sure the switch and the diverter are both working. You can test the electrical diverter easier than a manual one in some respects because to check the manual one completely you need to pull it. Have someone near the electric valve and hit the switch back and forth, then do the same near the tanks to hear if the sending units are coming on like they should. After that its a process of elimination if you want to keep the dual tank set up. You have to go from one system part to another starting from the switch, to the diverter and then each sending unit. If that doesn't work the last thing you can do is convert from manual to electrical and customize the switch in your cab to something less flimsy (The factory fuel switch is really cheap made and can be replaced with a custom toggle that has similar wiring. IF AFTER ALL THAT you're still not getting the system to work right I suggest removing it completely and installing a fuel cell under the bed of the pickup with a high performance sending unit. Beware of cheaply built filter socks on the sending units you shop for.

I have a 85 Chevy truck, duel tanks the one on the passenger side I never used it leaks. The tank on the driver side leak too, so I put a new one on that side. Truck runs for 10-15 secs. Than stops running after an hour or so go start it same thing. I replaced the engine fuel pump and carb filter, still does the same thing. What can it be.