Injection Pump And Fuel Lines

[ThaddeusW]

Ok I think i need a separate topic for this question. Today I pulled the side cover off the injection pump and saw a row of 6 springs and what appeared to be a rotating collar with teeth at the top of each spring. I assume those are the plungers and the toothed pieces on top make up the fuel rack which controls the throttle. Now there are two levers on the injection pump one that comes out of the top close to the fuel rack, I assume that is the engine cut off. There is a separate section on the back of the pump which has a larger lever which I assume is the actual throttle. Now when I moved both levers nothing moved behind that cover. Was something supposed to move or is there a problem?

Ok I circled the four parts of the fuel system I need help identifying.

The blue circles the rear of the injection pump which has the large throttle lever. What is housed in that part of the pump? The governor is back there correct? Also there is a round cover on the back that has four bolts holding it on, what is behind it? The red circle is around what the fuel pump? The yellow section is the actual injection system where the fuel is pumped to the individual injectors. The black circle is around what I believe is the fuel filter. Three lines run to it, one from the fuel pump to the side, one from the bottom to the injection pump. And the third runs from the return line to the top of the filter can thing.

I would appreciate any and all information about the pump and its inner workings.

[Rob]

Ok I think i need a separate topic for this question. Today I pulled the side cover off the injection pump and saw a row of 6 springs and what appeared to be a rotating collar with teeth at the top of each spring. I assume those are the plungers and the toothed pieces on top make up the fuel rack which controls the throttle. Now there are two levers on the injection pump one that comes out of the top close to the fuel rack, I assume that is the engine cut off. There is a separate section on the back of the pump which has a larger lever which I assume is the actual throttle. Now when I moved both levers nothing moved behind that cover. Was something supposed to move or is there a problem?

Ok I circled the four parts of the fuel system I need help identifying.

The blue circles the rear of the injection pump which has the large throttle lever. What is housed in that part of the pump? The governor is back there correct? Also there is a round cover on the back that has four bolts holding it on, what is behind it? The red circle is around what the fuel pump? The yellow section is the actual injection system where the fuel is pumped to the individual injectors. The black circle is around what I believe is the fuel filter. Three lines run to it, one from the fuel pump to the side, one from the bottom to the injection pump. And the third runs from the return line to the top of the filter can thing.

I would appreciate any and all information about the pump and its inner workings.

Well Thad, I'll answer your questions best I can:

The blue circle is in fact the governor of the pump as you mentioned. Under the round rear cover retained by four capscrews is the spring in which the rotating flyweights bear against via a sliding collar. Take the top off of the governor, and remove the round cover and you will be able to visibly see how the assembly works.

The red circle that you picture is the lift or transfer pump. This little pump actually pulls the fuel from the tank, and pushes this fuel through the filter, (your black circle) and then to the fuel gallery in the injection pump housing. There are three lines on the filter housing as you have noted: One is for fuel inlet to the filter, one is for fuel outlet from the filter, and the smaller hose from the top of the filter cannister is an air bleed line for elimination of air entrainment within the fuel. The transfer pump should pressurize the fuel gallery within the injection pump to about 15 psi when it is in good shape. The yellow section is in fact the high pressure injection pump.

The lever that is at the rear of the pump and mounted higher is the engine shut down lever. This lever when pulled to the rear pulls the rack to the rear of the pump rotating the plunger barrels to the "no fuel" position. This action shuts the engine down.

The lower lever is the throttle lever. This lever when pulled acts against the spring behind the round cover on rear of governor mentioned earlier allowing (through internal linkage) the fuel rack to be pushed forward in the pump by the flyweights and collar in the governor. When the opposing forces of spring pressure, and flyweight pressure are equal, (as in part throttle acceleration) the fuel rack holds it's position not rotating the plunger barrels further and allowing the engine to maintain a steady rpm.

That pump assy. really is not that difficult to work on. Best advice is to take it apart, clean it up, make sure everything operates freely and put it back together. When you have it off of the engine take the side cover off and rotate the input shaft of the pump. Make sure you don't have a spring that stays compressed, (stuck plungers do this). The springs look like little engine valve springs with small keepers. If you have one stuck in the up position, oil it up good, take a screwdriver blade wedged againt the back side of the keeper, and rap the screwdriver handle with a small hammer. It should pop free.

Good luck!!

Rob

[ThaddeusW]

Rob,

Thanks for the info. I still don't know if the thing works correctly. I will take the cover off the governor housing and see how that looks. When I pulled the cover on the side I saw the springs you mentioned. Everything looked in perfect order, very clean too considering how rusty and dirty the rest of the engine is.

I also see a line that runs from the compressor shaft housing to the injection pump, is that an oil line? How does the oil return bck to the engine as there is no second line? Does it run back through where it bolts to the gear train?

Is the fuel filter serviceable? It doesn't look like it comes apart. How easy is it to find a replacement or can a newer spin on setup be substituted? It had allot of old stagnant diesel sitting it it.

Also the transfer pump has a little knob which I assume is the hand primer. Only problem is that its rusted real bad, I don't think it will ever work again. I can unscrew it and the little spring and other parts inside look clean and operable only the handle wont budge. Can that handle part be easily found?

The third port on the filter comes together with the injector return line, a port at the top back of the injection pump and a line that I assume is the fuel return line to the tank. My best guess is that the injection pump has a fuel return on it as well. So maybe some of the injector and pump return can be fed back into the filter and in turn back into the injection pump .

[Lmackattack]

thad the air compressor is water cooled and oil lubed. as said before when you put the air compressor back on check to see if ther is a little hollow tube that is in the spline (love joy coupling) in the acc drive housing. this is where the compressor gets its oiling to the rod and crank journals on in the air compressor. the oil return will flow out of the compressors crank case and back down into the engine pan.

I was able to get my fuel filter replaced at NAPA. Simply remove the hose on top and unscrew the top nut off the canister. after the cap is off I belive the filter slides out. There should be a rubber o-ring under the cap to seal the housing. I also was able to get a new oil filter from Napa...

the primer pumps always rust. You can remove them and soak in PB blaster and see if that helps. Most of the time you need to dissasamble it and clean it up. or buy a new one as I think they have an updated version.

Trent

[ThaddeusW]

Thanks Trent. It looks like I might even need new injector lines too. Anyone know if there are any after market replacements? They look simple enough to make except for the coupling on the end. I would love to make my own out of stainless steel, never worry about rust again. The fuel return line from the injectors cracked as I was loosening its connection to the tee fitting on the injection pump . Thankfully that line can be easily replaced with a piece of tubing of the same diameter.

Oh does anyone know the injection pressure?

[Freightrain]

I'll see if I can find the Napa numbers for oil and fuel filters. That is what I run in mine.

The only issue I found with my fuel filter canister was the gasket on fitting(outside). Been off too many times, and then you couldn't tighten it enough to seal. Ended up dismantling the center fitting and installing new gasket I had in box of parts that came with my truck.

[Packer]

The one thing I remember from my days at Mack Truck (late '70's) was that the lines were 'EXACTLY' the same distance from end-to-end.

The fuel injection timing is based on pump to injector nozzle distance plus offset from TDC, and if the lines are not the same, the firing timing is different for each cylinder.

This will result in low power and/or high exaust temps, and higher fuel use.

Do-it-yourself is good but this may be one place to buy from the builder.

After all, how many times will you do this?

Those lines are 40 plus years old and even though they look bad, there might be 40 more years left in them!

Packer