73-87 Chevy _ GMC Trucks > Fuel Systems and Drivability

Yet another fuel tank selector issue


Sorry if this has been discussed, I searched and didn't see it, albeit it's odd, so finding the right search terms would be a challenge.

I replaced the switch and the selector valve already.  Additionally, the PO had already installed a new electric pump on the engine side of the tank selector valve. When I flip the switch the fuel gauge moves, but my fuel pressure drops to near zero and you can see the air bubble in the fuel filter start to grow as if it's being starved.  Odd thing is that the truck keeps running (at idle).

Where would you start to look?  Kinda perplexed at what should be my next step.

I would begin by stating the year/model/engine vehicle in question.  For better responses, never assume everyone knows on what vehicle(s) you are working. 

While waiting for a response, check all of the rubber hoses for condition (relative hardness, cracks, evidence of fuel seepage, missing clamps, kinks, etc) and hose routing.  Peruse the appropriate factory repair manual in the Technical Forum (Read Only) / General Information and Maintenance / 1973-87(91) Factory GM Pickup Manuals section of the forum for model-specific information pertaining to your truck.

sorry,  81 k20


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