Mark,
I hope others will chime in in case this is not the best advice, but if it were me, and removing the tank is obviously not an option, I would:
• Temporarily put a fuel filter between the pick-up and pump for a tank or two. I know that's not ideal, but a large diameter filter won't impede flow that much but it will trap whatever crap is getting stuck in the pump. Glass ones are great because you can see the crud.
• Consider draining all the fuel and washing out the tank with water (completely fill and drain) and then doing a final "rinse" with gas (which is disposed of later (could even be filtered fuel that you drained originally). Then let it dry as long as possible — perhaps aided by an air line dropped in to increase circulation.
I don't know any other methods. Obviously when fuel vapors are present you need to be really cautious about using any spark-producing tools to aid in the tasks.
I hope you get it resolved soon.
Mark
PANTERA INTERNATIONAL
A DE TOMASO CAR CLUB
Presents the De Tomaso Forums
The On-Line Meeting Place for De Tomaso Owners and Enthusiasts From Around the World
Clicking on the banner will take you to the sponsor's website.