i have a 67 chevy caprice 2 dr hardtop with 106,000 original miles, the original 396 was shot, put in a 454, the fuel filter stays full at startup, however after its warmed up you can see that it is almost completely empty and you can only see a trickle of gas running through it, my motor surges at idle just a little, and you can tell that something is holding it back, the fuel pump is a new holley mechanical unit -street type and i have replaced all the rubber hoses from the carb to the tank, however the problem still exists, the tank doesnt leak fuel, and does not appear to be rusted, the car has virtually no rust on the underside or anywhere else for that matter, including the trunk, my question is should i have my tank repaired or look for a reproduction tank?

I had the same problem on my 68 Camaro. I also had problems with gas gage so I replaced the sending unit and all rubber hoses and a good portion of it went away (still does it, but not anywhere near as bad). Don't be stupid around gas!!! There are a couple of things you can check pretty easy. Unhook the rubber line up by the fuel pump and blow into it. Depending on length, you might need to get a piece of smaller tube to put into it. Then have someone take off the gas cap and listen for air coming back into the tank. This will (hopefully) blow out anything that might be clogging the line, such as the screen on the tank pickup. If it gets better and then happens again, there could be something in the tank that it keeps sucking back in. Second thing you could do is take about a 6 foot piece of hose and run it from a gas can to the fuel pump directly. Then do it at the back bypassing the tank. If its better problem is in the tank, if not problem is most likely the fuel line. In either case, if problem is cured you have eliminated potential sources (clogged line, bad fuel pump, fuel line). If you drop the tank try to run it completely out of gas (I drove around neighborhood with a gas can), otherwise its very heavy and gas sloshing from side to side is a real pain. Be sure and do the testing when you are having the problem, and long enough to see if it comes back while testing. You can also check the line using a vacuum gage at the rubber line into the pump and then at rubber line just after the tank. I am not sure what the readings should be, but I'm sure it will be less back by the tank (maybe a call to auto parts/repair shop would be helpful to get rough range). I think the thing you need to look for is constant vaccuum otherwise it would indicate pin hole leaks in your fuel line. I bought a vacuum gage but have not used it yet, if you go that route, let me know how it goes.

[This message has been edited by TheGreen68 (edited 05-03-2001).]

Here are a couple of things you should try. First I would remove my gas cap and run the car (I wouldn't drive it like that though) and see if the problem goes away. If the problem goes away you have a venting problem which is causing you fuel flow problem (just kike if you ever tried to pour gas out of a can without opening the vent). If that is the case your cap could be bad or the wrong type for your application (some are vented and some are not). This could also cause your rubber fuel line to collapse. You should also check to see if you have a vent hose/line, if so you need to make sure it is not blocked/clogged or pinched. The last thing I would check would be the pick-up in the tank there should be a filter on the end of it (in side the tank) which could be clogged. You would be surprised on how much dirt some gas has in it, so just because it has no rust doesn't mean that it doesn't have dirt in it. Please post a follow up I would be interested to know what the problem turns out to be.
Royce

Have a fire extinguisher handy!!

I talked to one of the experts today. He said forget about the vacuum gage. Since I put in a new sending unit (without the screen as they suggested) and have a new fuel pump my problem is most likely with the hard line. I just put in another clear filter in front of the pump (always a good idea to keep junk out of the pump, especially if you take sending unit screen off as I did). Let me know what you find out.