And what is it's function. My '87 XLT 5.0 4x4 won' start. Guy working on my truck thinks it might be this part. So far he has replaced the in line fuel filter but not the in tank one, and the ignition control module. Battery is good. Rotor turns when ignition is engaged. Engine never fires up.

Some history. For years this truck has had an issue of not wanting to start when the enfine is hot. If the engine was hot and I turned it off it would sound as if the battery were almost dead before firing and starting. If it were hot enough I would have to wait 15 to 30 minutes before it would start. Could be totally unrelated but perhaps whatever caused that issue finally died?