Hello Gary,
Just flushing the fuel tank does not cure your fuel delivery problems in most cases.
The fuel tank has a screen built in the drain plug which I assume you have cleaned in addition the fuel tank has a baffle unit built in the bottom of it which we refer to as a "flower pot" (thanks Dan). This flower pot has a small port which is allows fuel to enter the flower pot so it will be picked up by the electric fuel pump. This port must be clear. Otherwise the car will run out of fuel every 15 or 20 minutes as the flower pot empties and is unable to refill through the port.
To counter this problem run test with a full fuel tank. This will allow fuel to flow over the flower pot wall keeping the flower pot full. Search up and read the "fuel tank tour".
The next item to inspect is the screen in the electric fuel pump. It is directly under the intake line fitting in the pump. It can be clogged.
The main fuel filter is the last line of defense. I assume this has been changed.
Lastly Check the fuel pressure and delivery quantity of the electric fuel pump. If the fuel pressure is too high the return fuel line is clogged. If the fuel pressure is too low or the fuel delivery quantity is low you have a restricted fuel supply, a problem with the return check valve on the injection pump or a defective electric fuel pump.
The fuel pump pressure should be 13.2 to 16.1 psi (.8 to 1.1) with the engine off, at least 1/2 tank of fuel, min. of 11 volts at the electric fuel pump and the fuel return line pinched off or blocked. Hook up the test gauge at the metal fuel line on the starter valve on the engine intake.
After the pressure check check fuel delivery volume by measuring the fuel pumped from the same fuel line (now open). The system should deliver about one liter every 15 seconds.
Download Attachment: pressure check.JPG64.26 KB
Hooking a fuel pressure gauge to the engine and temporarily installing it in the cockpit, then going for a test drive can be very helpful for diagnosis also.
After these checks you can be fairly certain that the fuel delivery system is operating correctly. You can now with confidence move on to other possible problem areas. Keep us up to date! Good luck.
Joe Alexander
Blacklick, Ohio