When I got my 91 7.3 about 6 months ago, I needed to replace the lift pump right away. The smell of diesel was so strong it made my eyes water, the fuel filter light would come on under load, and in the morning there would be the tell tale drips on the ground.

So I replaced the fuel line from the fitting on the frame to hose bib and replaced the lift pump. There was no more fuel smell, no more drips, but the fuel filter light kept coming on under load. It didn't matter which tank...the fuel light would come on under any sort of load. It even died on me going up a hill in the neighborhood.

I kept going over things in my head about what could be common to both tanks...bad fuel...bad fuel filter....transfer valve...air leak...????? No....No...No & No. It was driving me crazy. I was not getting anywhere and becoming more desperate...maybe injector pump?...My diesel buddy (& voice of reason) wasn't buying it.

Maybe it could be a clogged tank selector valve..."did you replace the line from the frame to the lift pump?" I did. But I would check it.

As soon as I did the problem was apparent. The line was just a little too long and it is a very tight turn, so there was a hard kink (restriction) in the line. I cut the line a few inches reattached it...no kink...problem solved!

I have seen several several fuel filter light posts, with similar symptoms, but haven't seen any solutions. If this is happening to you check this out.