Remove Roosa Master Injector Pump

I have an 856 Custom with the diesel engine. It is my primary snow blowing machine. I went out this morning to remove some drifts from the driveway and the tractor will fire and then die. Crank and it will
fire and die. I went to the University of Google for information and found that I could determine if the retaining clip has disintegrated by loosening the cover on the side of the pump until fuel leaks out.
Start the tractor and if it runs fine while fuel is leaking out, but dies when closed off then it is a good sign that the retaining clip has started to come apart.

I have worked on gas engines a lot and some minor diesel work like replacing injectors on a truck and replacing glow plugs, but I have never removed an injector pump so I want some advice since I read horror
stories all over the web. It is a Roosa Master pump. I have found that you want to find TDC compression on #1 before removing the pump. I have a neat trick I was taught as to how to find TDC compression on a
gas engine that involves removing the spark plug and replacing it with a makeshift paper towel plug and then tapping the starter until the plug pops out and then you can turn it by hand after that. However,
I'm not sure how to do this on my 856 without pulling the valve cover. Is there any way to do this without pulling the valve cover?

Once TDC compression is found and it is time to remove the pump, should the shaft go with it? Sounds like there are different views on this. What is the consensus here? I will be taking the pump to a local
shop here to do the rebuild as I do not want to screw this up since we could still see a lot of snow before winter is over. What do I need to know about the timing on the pump? Do I wire the throttle wide
open? Can you assist me in a walk-through of what many say is a simple process but yet I read lots of horror stories about injection pump replacements gone bad. This form has always been great with advice
and I feel bad that I take and do not contribute, but please know that it is greatly appreciated.

First, verify that the return line to the tank is not clogged/frozen/damaged.

Disconnect the return line from the fitting on the top of the I.P. and try again to start it. If it runs, figure out what's clogged between there and the tank.

If it DOESN'T start with the line disconnected, remove the adapter fitting from the pump cover and check to see fit's clogged with dark coffee grounds-looking pieces of the governor damper ring, that will be a sure sign the originally almost clear-looking plastic has deteriorated and come apart.

If it has to come off, rotate the engine while looking for the timing mark in the little timing window on the I.P., when the mark comes into view it's a sure indication that #1 TDC on the firing stroke is coming up.

Thanks, Bob! I will give this a try tonight when I get home. I will be very thankful if it's just a frozen/plugged return line. I will post back and let you know what I find out. The weather is actually going to be in the positive 20's this week so thankfully she held out through the -20 weather.

As Bob said, align the pump marks under the side cover, if I recall flywheel should then be at six or eight degrees BTDC. On ANY 361/407 pump I repair I insist on removing the drive shaft assembly too and replace the shaft seals inside, as seals ARE NOT in the pump on that application. The four bolt cover comes off the front, then the shaft nut and washer is removed. Shaft/adapter assembly is then pulled back out of the pump drive gear, drive shaft is straight, not tapered and most come back easily.

Does this engine have a side cover for lifters? If so you could remove that for tdc on compression stroke along with crankshaft pulley mark. I may go to the University of Google later to find out since I'm curious.

So an update on my findings. As suggested, I turned the valve off at the tank and I pulled the return line off from the pump. I crawled in the tractor and started it and it ran and never died. When I removed the line I did not notice any debris, just clean, red, fuel. With the line off, I then turned the valve on at the tank and no fuel leaked out. I took the air compressor and tried to blow air back into the tank with no luck. Looking down in the tank, the valve area looks clean and doesn't appear to have anything blocking it.

My guess is that the line is actually frozen. We had a stretch of -20 and colder and when I blew snow the temps were hanging around the -12 mark. Now the temps are back up above 0 and have been bouncing around the teens and twenties lately. I'll have to pull the battery to get at the line on the tank, but I will pull the line there and then open the valve to see if the issue is in the line or the valve.

I am hopeful that I can get everything going again before the next cold/snow hits. For those who run their diesel tractors in sub-zero weather, are there any additives you like to use to help prevent freezing? I always run straight #1 in the winter and this is the first year I have had an issue, but the wind was blowing hard the last time I blew and I had snow blowing all over the tractor so the idea of extra water mixing with the fuel is a definite possibility.

Thank you again for all of the great information. It is getting stored in my memory bank for the future what-ifs.

A 856 custom has a check valve in the return line at the bottom of tank because they use the fuel tank like a 756 and not like regular 856 that returns to top of tank.

Probably iced the check ball. You need to drain water trap line regularly to remove moisture from tank.

Weekend Update:

I ended up taking the return line completely off the tractor and used air to blow through. I have learned that I will never buy fuel from that distributer again. The pump said #1 on it, but the gelatinous mess that came spraying out of the line tells me a different story. There is no way this was straight #1 diesel. Once the line was clear and installed back on, the 856 is once again alive and well. The tank has now been treated with Diesel 911 and as the fuel gets used, I will be topping off with fresh fuel from the supplier I normally always go to. I am so relieved that the IP was not the issue in this case. Thank you, everyone, for the help. All previous suggestions are being stored for the future if the pump needs to be removed down the road.