1989 V3500 fuel selector valve

[kjnmontana]

The switch that was in the truck was a “Depress Fully” which I thought was the carbureted version and I’ve read where the AC Delco D7089C is for the TBI...?

[VileZambonie]

Carbureted should be Delco D7003 or Standard DS293 which is Depress Fully
TBI Should be Delco D7089C or Standard DS1807

[VileZambonie]

Two diagrams below. First is TBI, second is Carbureted.

[kjnmontana]

The depress fully which I assumed was for carbureted meanwhile I’m seeing some amazon switch reviews saying the ac delco d7089c is for TBI...?

[kjnmontana]

Vile, thanks much to you and BD...the education continues

[bd]

Carbureted should be Delco D7003 or Standard DS293 which is Depress Fully
TBI Should be Delco D7089C or Standard DS1807

This ^^^^^.

I am trying to determine what the actual differences are between the two switches besides the keying (polarization) of the connectors and the fact that the "Depress Fully" switch is momentary contact.  More on this if/when information becomes available.

In the meantime, it sounds like you have the correct switch.

[kjnmontana]

Guys, can anyone explain the logic of the molded pin connector in the fuel gauge wire near the fuel block valve that Hatzie depicts in his Dual Tank Theory post?
I’m absorbing the schematics provided above and trying to understand how this connector should be incorporated into the fuel block valve wiring harness and Fuse 30 on the engine compartment fuse block.
Thanks

[bd]

Do you mean this ^^^^^?

The pink wire pictured is circuit 30 coming directly from the fuel gauge.  On a single tank system, Ckt 30 routes directly to the production tank.  On a dual-tank system, it routes to the selector valve; the selector valve switches the dash gauge (Ckt 30) between tanks. 

Don't confuse Ckt 30 with Ckt 139 (also a pink wire), which does connect to the fuse box.

[kjnmontana]

Got it, curious as to why a molded pin connector is required vice a straight wire from the fuel valve to circuit 30 via the wire harness?

[bd]

Dual fuel tanks are an add-on option from the factory.  It is simpler and less costly to add the NL2 harness to the existing single tank production wiring.

[kjnmontana]

Hey guys, I’m looking at the Pollak two tank motorized fuel selector valve installation sheet and I’ll be giggered if the main and aux tank leads from the wiring harness are the reverse of what your schematics...?