See full version: How to Bleed a Fuel Line
Re-pressurize the fuel system by shutting the valve and turning the ignition to the "on" position (the position just before the crank position where you attempt to start the vehicle). You will hear the fuel pump prime the system. When the pump stops, turn the ignition off, and turn it back on again, and allow it to pressurize the system again. Repeat this process several times.
The fuel line carries the fuel from the fuel tank to the fuel injection system in your vehicle. Fuel lines are under high pressure. Whenever you work on them, you'll need to relieve that pressure using something called a Schraeder valve, which is located on the fuel rail in most vehicles. When you are done working on the fuel system, purge the system of air. To do this, you must know how to bleed a fuel line.
Open the hood of your vehicle and locate the fuel rail. This is normally located towards the back of the engine bay, on top of the engine towards the firewall.
Locate the Schraeder valve. This valve looks like a valve stem that you would normally find on a tire. This valve is a bleeder valve that will release pressure and purge air from the system if you loosen or remove it. On some vehicles, you may be able to press down on the valve to release pressure. [links]
Place a rag over the end of the valve, and either loosen the valve with the wrench or depress the center of the valve with the flat head screwdriver. You will hear air coming out of the valve, but you may also notice gasoline spraying out also. The rag is to prevent the gasoline from spraying all over the engine bay. here
Repeat steps 3 and 4 again. This should ensure that your fuel system is properly bled and is working as it should.
Massey-Ferguson manufactured the 135 tractor from 1964 through 1975. When equipped with the three-cylinder Perkins diesel engine, owners could expect years of trouble-free service. Although conventional tune-ups are not necessary on a diesel engine, regular maintenance of the fuel filters is critical for the proper operation of the injection system. Once both of the fuel filters have been changed, it is likely that air has entered the fuel system, requiring the filters and the fuel system be bled before the engine will run properly.
Place a drain pan under the fuel filters on the left side of the engine. Loosen the thumb nuts on the bleed screws on the bottoms of both the fuel filter housings and allow the fuel in the housings to drain into the pan. more
Loosen the bleed screw on the upper side of the fuel injector pump with a wrench. Move the lever on the side of the fuel pump block back and forth by hand until fuel begins to come out of the bleed screw. Tighten the screw with the wrench. [links]
Most diesel engines have their fuel lines covered by a valve cover. Remove that valve cover to have easy access to the fuel lines that connect the combustion chamber to the injector pump. here
All diesel engines have an injector pump that is connected to injection fuel lines. The injector pump helps pump fuel into the diesel engines cylinders at a very high pressure, around 15,000 Psi, so that the fuel can be slowly injected into the combustion chamber. Whenever there is excess fuel, it is used to cool down the injectors and is then returned to the fuel tank with the help of valves. During this process, air bubbles can be formed in the injection system if the engine is running on low fuel or if there are fuel leaks in the injection lines. For smooth engine function, it is important to bleed an injector pump of any air so that fuel can easily flow to the combustion chamber. This step-by-step guide will help you bleed an injector pump easily. The tools and materials required for the job are given below.
Now that the major fuel connections from the combustion chamber to the injector pump have been opened, put the fuel control position to 'No-fuel'. After doing this, tip the engine over by using an engine mount with chains. Do this very carefully with the help of a friend as engines are really heavy and dropping it onto yourself can cause serious injury. When you tip the engine over, fuel will start pouring from the last injector that you took off the bolt from. Observe air bubbles while the fuel falls to the ground. As soon as you notice a smooth fuel flow without air bubbles, use a wrench to put back the bolt tightly on the last fuel injector. You have successfully bled the injector pump.
The first step is to ensure that all the lines of the fuel system are installed correctly and that there is no dirt-clogging causing irregular fuel flow. After doing that, all the lines between the combustion chamber and the injector pump must be checked for fuel leaks. Any tiny fuel leaks in the lines can cause air bubbles too.
To do this, use a wrench to open the fuel bolt of the last injector in the fuel injection system. On most diesel engines, the last injector is the forward-most one. You can refer to your car's manual to confirm which injector is the last one. Be extremely careful when working on the injector pump as causing a break here can lead to the high pressure fuel coming out at you. The fuel is at such a high pressure that it can penetrate human flesh and can cause serious injury. here
A good news story! The Perkins AD3.152 on my MF40 was running after a rebuild, but sounded like only 2 out of 3 cylinders were firing. No smoke, but no power - I thought this was probably just air on the system and set about bleeding all air from the diesel lines. After 15 mins of bleeding, I still had lots of tiny bubbles at the CAV DPA injection pump outlet union for cylinder 1, as well as at the injector pipe union itself. After an hour of internet trawling, I decided to swap the no1 and no2 injectors to make sure the problem was air from the injection pump, or at least from the no1 pump lines. here
Wonder of wonders, the problem moved to cylinder no2. I broke down the 'duff' injector and apart from cleaning it, did little else - I did 'tighten' the spring tension inside the top nut a little just by 'feel' - but it was all trial and error as I had no pressure-test gear. After re-assembly and with hardly any bleeding whatsoever, it started beautifully on all 3 cylinders. No smoke, full speed range.
With air bubbles down at the pump, as well as at the injector, I would never have thought the problem was at the injector but it must have let HP combustion gas leak-back into the fuel feed line, giving the appearance of air in the fuel. Weird.
I guess this could apply to lots of different engines not just the Perkins - hope it helps someone else