Well I know I'm wading in a little late but here is what I would do to troubleshoot the problem: You have the same problem with a mech fuel pump and an electric one, so I feel that you can safely rule out the pump. If in your boat, I would now take a long stretch of hose that is hooked up to inlet side of your pump, and run it into a can of some sort that has fuel in it, even if it is a 1 or 2 gal fuel can. Now I know what I'm going to say is obvious but I'm just say'in for those that read this and don't know the 'obvious' ...whatever can you use, don't use a glass jar, keep said can far away from any ignition sources and keep the hose away from any heat that can melt said hose. Also, do this OUTSIDE and not in your garage and by all means: keep a fire extinguisher handy. Best to have 2 people just in case- one to hold the hose and keep the extiinguiser handy while you check what is going on. Anyway by doing such, you remove the tank and pickup from the mix. If it IS a heat problem you can bird dog it down from there 'cause the same problem will show up. If the car runs fine, they you've found your problem- something in the pickup assy is causing you grief. Just my 2 cents....