I have recently acquired a '68 Caprice for use as a daily driver, it sat for 8 months prior to my getting it. I replaced plugs, wires, cap, rotor, points and condenser, and installed a low mileage q-jet from a running car. It started and idled great and ran well except for a surge on harder acceleration that I attributed to bad gas. I ran a tank thru it in a weeks time and last Friday, it started losing power and died. After sitting a while it restarted and ran with a heavy surge then died again. After a few times of this, it would not start at all. I found no fuel coming from the pump, so I replaced it and after priming the carb, it started and ran great with only a light surge for a few days. Out of nowhere yesterday, it died and would not restart. Once again, no fuel from the pump. I replaced the pump again and it would start and run but ran rough and would not idle. I blew back thru the pump with compressed air in hopes that if something was stuck in the sock, it would dislodge enough to let it run. Now it wont start at all. Did I ruin the pump by blowing back thru it? Is there junk in the tank thats starving the car for fuel? I have no vac leaks and the ignition system appears to be ok. I am really stumped and need to resolve this asap. All advice and wise remarks appreciated :)

Sounds like to me you have crap in the tank that's clogging up the sock. It's probably floating around in the tank. I'd pull the tank and try and clean it out. You may be able to look in and see if there is rust inside that will keep coming off.

Once I took my Elky tank to the radiator shop to weld a crack at the filler neck. They of course flushed it prior to welding it. While I had it off, I removed the sock and had them weld another pickup in the place of the return line to use for a dedicated nitrous system. I had one of those little glass in-line filters between the tank and the fuel pump and the first time out, it ran about 20 minutes before becoming clogged with rusty crap. I cleaned that thing 10 more times before I said heck with it and got me a big 'ol fram canister filter and never had another problem. I guess it would eventually clog but never did while I had it.

Thats what I'm thinking, I just wonder if I blew out the diaphragm in the fuel pump by blowing back thru it.

I'm afraid you may have. In the "olden days" I had someone verify the pump was bad by blowing thru the fuel line (prior to the pump) (ie. the pump was bad if you could blow thru it to the tank). If you can find a cheap elec pump to test it, you'd know for sure.

I finally found the problem, thanks to some advice from the T-Man, and some help from a local friend who was not as frustrated as I was. There were several pinholes in the metal fuel line where it went up the frame by the rear axle, and as they got bigger, they caused the fuel pump to pull in more air than gas when when under a load. The harder I accelerated, the more air came in and caused the car to nose over and die. This also explains the hard starting and having to prime the carb to get it to run. On the bright side, I now know that my complete fuel system is new and up to snuff and that my gas gauge is spot on!
Thanks Tom!

Now you know why the car was sitting and not being used.

Well, we bought the car on ebay in Feb, and I flew to Miami from Houston and drove it 1,200 miles home with no problem. The sitting was at a bodyshop after we got it back here, and the problem started after I began driving it daily. I think the corrosion had started a long time ago and finally broke thru. Better now than on the road from Miami!