Injection pump - getting the air out / priming procedure ?

[rkpatt]

injection pump - getting the air out / priming procedure ?


I recently had a situation with some bad fuel which quickly clogged the fuel filter and the engine stopped . I filled the new filter wiht fuel and installed it . This model does have the bleed line at the top of the filter housing .

This model does have the bleed line at the top of the filter housing . I am also using a Facet Purolator 4-6 psi electric fuel pump instead of the mechanicial lift pump .

It took me a very long time ( probably 30-35 ) starter cycles on jumper cables with at 10-20 min cooling in between to finally get the engine started .

Should the injection pump generate pressure immediately ? Is there something wrong mechanically ( IP or electric fuel pump pressure ) or with the procedure ? Any explanations and help are appreciated . -

 

[Exekiel69]

With the electric pump should be really easy to bleed the air out of the system, once the fuel is in the filter then pressure is ON. Now I don't know about the electric pump you say but I would think it should be easy.

 

[zigg]

Wow, something's wrong there. When I change the filter, I fill the new one, put it on, turn on the ignition(fuel pump runs) and by the time the glow plugs are cycled once, the fuel system is primed, and it fires up within a few revs of the engine.


I can't figure that one out. Either your fuel pump isn't working or I'm not making sense of it at all.

You may have airlocked the injectors. If you run them out of fuel, you need to crack the lines at each injector, then spin it over with the fuel pump running till fuel shows at each of the injectors. Then button it back up, and it should start pretty quick.

Zigg

 

[rkpatt]

Another ? . Early in the process of trying to start it and trying to figure out what was wrong I remove the to hose to the brass fitting on top if thei injection pump (injection pump overflow check valve ) . No fuel came out when the electric pump was on or when I was cranking the engine . I presume fuel did come out of it later when I later go the engine started . What is the exact purpose of the valve and how should it function ?

Air locked lines ? Does this mean every time something like this happens I need to cack all of the injectors and crank and crank to bleed the system ?


Also - A friend on mine mention to me that some injection pumps require a certain minimum lift pump pressure and suggested that I switch to a slightly higher pressure lift pump like the Master E8012 6-9 psi model . Does this sound reasonable ?

Thanks

 

[tuckerd1]

I am also using a Facet Purolator 4-6 psi electric fuel pump instead of the mechanicial lift pump .

Ford service manual specs says lift pump should have static pressure of 6-8#'s.

 

[Exekiel69]

You may have airlocked the injectors. If you run them out of fuel, you need to crack the lines at each injector, then spin it over with the fuel pump running till fuel shows at each of the injectors. Then button it back up, and it should start pretty quick.

Zigg

I never heard of that one. So if I have air in the lines turning the pup ON and crank until it runs 5 seconds latter is no the thing to do? Ops.

 

[rkpatt]

Today my truck stalled again acting like it was running out of fuel or a clogged filter . I did not observe any water . I changed the pump to a Master E8012 electric 6-9 PSI pump . There was a strong stream out of the filter with pump on . I still had this problem (slow to get fuel into the IP and took forever to come out of the cracked injector lines and the upper pump check valve line ) but the engine eventually started after many tries ( on jumper cables and cooling in between . I am missing some thing here but I can't figure it out because I don't fully understant how this system operates. I wonder if the IP is going out or what ?


A couple of other observations and questions :

1. I opened the water drain on the bottom of the filter and nothing dripped out (electric lift pump off, of course) . I think maybe it is draining back . Why ?

2. Can someone explain that bleed hose system at the top of the filter base - Is it just an orifice or is is there an integral check valve.

3. Return line fitting on top of the injection pump - Should fuel be coming out of this fitting with the electric pump on but with the IP not turning ?


I seem to be stuck at this point . All help here is greatly appreciated - Thanks

 

[tuckerd1]

All I can come up with for the moment. Hope it helps.

Fuel System



Fuel from the tank is routed to the fuel supply pump through a combination fuel filter, heater and water separator. The filter header contains a continuous vent (orifice bleed- off system) which aids starting by eliminating the need to manually prime the fuel filter. A vacuum switch is incorporated into the fuel filter header which will activate an instrument panel lamp, indicating the need for filter replacement. The water separator portion of the filter assembly has a probe which activates an instrument panel lamp when the filter requires draining at the water and sediment drain (located on the bottom of the assembly).



NOTE:

Proper filtration of diesel fuel cannot be overemphasized. It is essential for long component life and reliability.



Fuel enters the inlet of the injection pump and is delivered under high pressure through injection nozzles into the engine cylinders for combustion. Each nozzle incorporates a fuel return fitting that returns excess fuel to the fuel tank. Excess fuel from the injection pump and each injection nozzle is collected in bleed-off lines and returned to the fuel tank.



Injection nozzles are located on the inboard side of the cylinder head. This configuration provides better access to the engine for servicing.



The fuel shutoff solenoid controls the flow of fuel into the injection pump charging circuit (high pressure). With the ignition switch in START or RUN, the solenoid is energized and fuel is allowed to flow to the injection pump charging circuit. With the ignition switch off, fuel flow to the injection pump charging circuit stops.



Injection Pump



The diesel fuel injection pump accurately meters and delivers fuel to a nozzle in each cylinder at high pressure and at precisely timed intervals.



Refer to following illustration for pump operating principles. Fuel flows into the injection pump inlet through an inlet filter screen (1). Fuel then flows to the vane-type fuel transfer pump (2). Excess fuel from the transfer pump is bypassed through the pressure regulator assembly (3) to the suction side.



Fuel under transfer pump pressure flows through the center of the transfer pump rotor, past the rotor retainers (4) into the hydraulic head. It then flows through a connecting passage (5) in the head to the automatic advance (6) and up through a radial passage (7) to the metering valve (8). The position of the metering valve, controlled by a governor, regulates fuel flow into the radial charging passage (9) which incorporates the head charging ports. As the rotor revolves, the two rotor inlet passages (10) align with the charging ports in the hydraulic head, allowing fuel to flow into the pumping chamber. With further rotation, the inlet passages move out of alignment and the discharge port of the rotor aligns with one of the head outlets. While the discharge port is opened, the rollers (11) contact the cam lobes forcing the plungers together. Fuel trapped between the plungers is then pressurized and delivered by the nozzle to the combustion chamber.



In addition, an air vent passage (12) in the hydraulic head connects the outlet side of the transfer pump with the pump housing. This allows air and some fuel to be bled back to the fuel tank through the return line. Fuel bypassed in this way fills the housing, lubricates the internal components, cools and carries off any small air bubbles.



Injection Nozzle Assemblies Description



The injection nozzles are of the inwardly opening, differential, hydraulically operated, pintle-type. Their function is to direct a metered amount of fuel, under high pressure from the fuel injection pump, into the engine combustion chamber.



The injection nozzle assembly consists of two subassemblies. The nozzle holder retains the nozzle in its correct position in the cylinder head and provides channels for conducting diesel fuel to the nozzle. The nozzle consists of two parts: valve body and nozzle valve. These parts are lapped to form an extremely close-fitting matched set.



The nozzle valve carries an extension at its lower end, called the pintle.



Operation



A metered quantity of fuel passes through ducts to the pressure chamber located just above the spring seat. At the instant the pressure of fuel acting on the differential area of the valve exceeds a predetermined spring-load, it lifts the valve from its seat and fuel flows from the nozzle. Fuel cut-off occurs as the valve is seated by the nozzle spring. A small amount of fuel leakage to the spring cavity is necessary for lubrication. This fuel leakage drains through to a leak-off outlet.

 

[rkpatt]

Is there any kind of screen or filter on the injection pump it itself ? - Thanks

 

[rkpatt]

An update here - I am getting air in the system somewhere or is it draining back where I turn off the engine and picking up air . I am pretty sure that I have eliminated the air leaks between the electric pump intake and the tank . I removed the bleed orifice , found the check ball and spring and flushed it out What else could cause this to drain back down and let air in ?