i have an F 150 with dual tanks that has been sitting many years. I finally got it running yesterday. I went out to start it this morning and it had changed to the rear tank and is now stuck there. the switch on the dashboard is not switching the tanks but it was yesterday. Is it the switch or a more major problem?

 

What makes you think it's running off the rear tank? The dash switch only changes which tank's pump gets power, and which tank's level sender is connected to the gauge. Read these captions:

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