Borrowed from Les Addison on 4wdAction site
"Air leaking into fuel systems can be very difficult to find as some times it wont show a fuel leaking joint, and can cause all sorts of problems. It can be done easily with the right tools. All you need to do is to get a few short pieces of clear plastic hose to suit the sizes of your system, and a couple of brass joiners. Start from the fuel tank, install the clear hose, start the engine and check if there are bubbles. Repeat this sequence at all joints.Throw away fuel filters are prone to suck air from the rolled edges, CAV types can, through the rubber gaskets,and O rings ,tapered brass barbs, and sometimes cracked aluminium housings. Make sure you fit the clear hose to the return line from the injector pump to the tank as air can be sucked through worn or faulty seals. It pays to check the fuel cap for faulty vent action as this causes a vacuum in the system which may suck air at a faulty joint and will sometimes draw fuel from the lift pump/ injector pump causing shut down after a short run then hard starting. Les "
"Air leaking into fuel systems can be very difficult to find as some times it wont show a fuel leaking joint, and can cause all sorts of problems. It can be done easily with the right tools. All you need to do is to get a few short pieces of clear plastic hose to suit the sizes of your system, and a couple of brass joiners. Start from the fuel tank, install the clear hose, start the engine and check if there are bubbles. Repeat this sequence at all joints.Throw away fuel filters are prone to suck air from the rolled edges, CAV types can, through the rubber gaskets,and O rings ,tapered brass barbs, and sometimes cracked aluminium housings. Make sure you fit the clear hose to the return line from the injector pump to the tank as air can be sucked through worn or faulty seals. It pays to check the fuel cap for faulty vent action as this causes a vacuum in the system which may suck air at a faulty joint and will sometimes draw fuel from the lift pump/ injector pump causing shut down after a short run then hard starting. Les "
