Truck Repair: fuel problem, dual fuel tanks, fuse block

Question
Have A 88 Ford F250 with dual fuel tanks. Noticed yesterday that when I turned off the engine that there was an whine coming from the fuel tanks. It is fuel injected. I disconnected the battery to get it to stop. Any suggestions on the remedy to my problem. Thanks

Answer
I believe there is a relay sticking, probably located under the hood, in the fuse block.
The cover should say which one it is. You can probably swap it with another, like the trailer light relay, and see if that fixes it. If so, get a new relay.
Van