I have recently discovered a problem. My truck runs fine and will start right up but sometimes it will crank over but wont fire. A few years back I had to replace the wiring harnesses and a few months ago had to replace a injector wire. But just recently it has been having a problem with wanting to start. Yesterday it ran fine all day but then I parked it for a minute and it wouldnt start. I made sure it was getting fuel but it still wouldnt fire. After 20 minutes of screwing around I finally checked the relays and changed the one that has to do with the injectors or the pump and it fired up. Is this common with lb7s? Mine has 147,300 and never had injectors

 

Did you take the old relay apart to see to if it got wet or ant's got in it? to cause it to go bad? Or if the contacts are loose in the relay distribution box?