Roosa Master DBG - No Fuel Problem...

I just bought a Allis Chalmers M100B road grader. The folks told me that it was running and then just quit. It has been sitting for awhile now and I am going to give a shot at making it run again.

This is what I have so far (new to this beast so bare with me). The fuel line from the tank hits two fuel filters that are about two inchs above the tank outlet (I guess that fuel must be above a certain level before you may use it). Then the line runs to the "IN" on the top of the Roosa Master DBG pump.

There is one line on the bottom that is connected to the "OUT" fitting on the pump and appears to go to a gauge inside for Fuel Pressure.

There is one line that comes out of the top of the pump that connects with a tee from the injectors and connects to the return on the fuel tank.

There is six lines from the pump that travel to the injectors.

Here is where I am getting a little confused. Does the fuel connecting to the IN on the pump have to be pumped (under pressure) or is the gravity fed system correct? If the gravity fed system is correct, then is the end part of the pump with the fuel IN and the OUT on bottom the pump? If so, then if I have good fuel flow to the IN, getting small drips of fuel on the OUT and nothing at all coming out of any of the injector or top return lines, then is it possible I just have a bad pump?

I appreciate your help with this and anyone with pics of schmetics or anything they would like to share, PLEASE do so. I haven't yet ordered a manual for rebulding this pump because I am not sure which would be best, so any input on this would be great too.

The IP has an internal vane pump, and will lift/draw fuel up a reasonable distance WITHOUT the need for an external lift pump.

180º across from the port marked "inlet" on the IP there is a bleed plug. Start by loosening that plug, then crank the engine and see if fuel is pumped out the bleed plug.

If you get fuel that far, remove the line from that top of the pump that tee's in with the injector return lines, and the fitting/valve beneath it, and crank the engine 'til fuel comes out that port. Then, loosen the lines at the injectors (usual fuel spray cautions apply) and crank the engine 'til fuel gets to the injectors. At that point, tighten the lines, and the engine SHOULD start.

Since the engine stopped suddenly, there IS the possibility the IP driveshaft could have broken. If you can't get fuel out the vane pump bleed port, that's the first (of several) things I'd suspect.

Remove the timing window (about 1/2" X 1 1/4 ") held on with two screws. Crank the engine and see if one half of the metal inside the window moves. That will tell you if the pump shaft has sheared off if you see no movement.
Your filters could be plugged.If you have no idea how long it has been since they were replaced, that would be the first place to start.

Having that gauge seems strange, I've never seen it done OEM. I've seen a few home-made hookups where people wanted to monitor interal fuel pressure that runs the timing advance (60 PSI gives full advance).

How high does the gauge go?

Before you get too involved, you ought to pull the little rectangular timing window off the side of the pump. Then turn the engine over and see if anything side is moving. If the pump shaft did NOT break, as Bob already mentioned, you'll have the parts inside moving whenever the engine is spinning. If you see nothing moving, you're screwed. Shaft if broken and pump probably ruined. If half of what you see is moving, but you find little specs all over that look like mouse turds - the pump needs a teardown and some parts.

The gauge doesn't show numbers, it just has RED on the lower end (about 10% of the gauge) and the rest is GREEN. I guess the goal here is to stay in the GREEN. I purchased this grader from the US Air Force. I can only assume that it was an option that they required.

I was still unable to get fuel to come out any where on this IP. I do have great fuel flow up to the inlet on it though. I took the timing cover off and the internal parts are turning (thank god), so I went ahead and pulled the pump off.

I ordered a manual online and bought a kit for it local yesterday. I am going to give my best effort and going through this thing and see what I can find and repair. This will be my first, so an advice is appreciated.

Also, wanted to thanks for all that has responded. You guys are the pros in my book and myself and others feel more comfortable knowing you all are willing to provide professional advice. Thank you!

NEW PROBLEM:

Okay, so I rebuilt the pump and things were starting to look up. I was incorrect on the Fuel Pressure Gauge, it goes up to 80 and red lines at 40. Once I got the pump back on the motor started and ran fine. Fuel Pressure Gauge shows 80. After it ran for about 10 minutes or so, it started dieing. It will start and run for about 10 seconds and die again.

Here's what I have so far:

-I have a good stream of fuel going into the pump from the tank.

-I have good fuel that comes out the outlet on the bottom below the inlet when the motor is running or cranking over for that matter.

-I do NOT have fuel coming out of the top of the pump that is connected to the return line that goes back to the tank

-I do NOT have fuel coming back from the injectors via the return line to the tank.

-I do have a rise in oil level when I check the engine oil.

Does this sound like something major or did my seal that is on the shaft from the engine get hosed up when I put the pump back on? I just lined it up and slid it in. Is there a trick to this?