Hi Jim, I have just seen the results of a pump failure which sounds like yours, the pump has been dismantled to inspect it and there is a "Tar like sticky substance on the working parts. It has been diagnosed as having been run with "contaminated fuel" The chap who's problem this is, has a CAV diesel fuel pump from a marine engine Which has been running Red diesel. Try to check if there is the slightest of deposits in the tank or pipework rub it between your fingers and see if this goes slightly sticky. If so when it run's through the pump it gets thicker over time and ruins the pumps pistons. My mate ran his engine perfectly without a missed beat, shut the egine down and it refused to even attempt to start.
Dave
June 2008