A lot of good advice here.
Also, I have had my 4-108 shut off like someone pulled the fuel shutoff lever. In my case it was a small air leak at the lift
The first thing I learned online when searching for an answer to how to bleed a 4-108 is that few people change their fine filter because 4-108's are a bear to bleed.
Here's where I'd steer:
1.) Make sure you have fuel to your primary filter. If no fuel there, look for a plugged tank vent or plugged pickup tube. Be sure both tubes are free flowing.
2.) Make sure you have fuel coming out of your primary filter. In my case I installed an electric fuel pump
after the primary filter. I use that pump to determine that I'm drawing fuel from the tank, through the primary filter and to the pump.
3.) The next place to check is fuel flow through the lift
pump and through the fine filter. That bleed screw is my 4-108 is at the top of the filter. This was where I finally found my problem was. I had fuel flow to run the engine
for about 70 seconds, (After bleeding injection pump and injectors,) but I noticed a tiny fuel leak on the fine filter and tightened it a bit. What I didn't realize for awhile was that I had reduced fuel flow through the fine filter even more, to the point of not getting enough fuel past the fine filter to run the engine. Be sure you have good fuel volume through the fine filter!
4.) Once you have good fuel flow through the fine filter bleed the points farther down the line. There's a good video online that I'll find and post a link to on how to bleed a 4-108. If my memory serves me correctly you need to bleed the governor screw on top of the injection pump. For me that required a 1/4" ratchet, a long 1/4" drive extension, then a universal joint and the correct size socket.
The next bleed point is on the side of the injection pump. I used an 8mm open end wrench to crack that open. ( The 8mm fit better than the 5/16")
I believe the order is, bleed the 8mm/ 5/16" bleed screw on the side of the injection pump. Close it up after good fuel flow and no air. Then bleed the governor. ( The nut on top with socket and universal joint. Get good fuel flow and no air and close that up. Next, follow the pipe from the fine filter to the injection pump. Loosen the nut where the pipe enters the injection pump. Get good fuel and no air.
5.) Next crack open all four nuts on the pipes entering the injectors. Turn the engine over using the electric
starter. (Be sure your raw water
seacock is in the off position!)
In a few seconds the pipes at the injectors will start spurting air a fuel. Give them a few seconds, and begin tightening the nuts on the pipes, starting with the injector spurting the largest volume of fuel and working your way down the line.
6.) The engine will start. Turn on the raw water
I'll go look for that YouTube video on bleeding a 4-108 and post it here.
This is probably the video:
This and the Perkins
manual was enough for me.
Here's the 4th in a series of videos:
There are few things nicer in life than cracking the injectors, getting fuel and snugging them up to the sound of a 4-108 ticking away.
Also, don't run your electric starter for more the 35 seconds every several minutes. Let it cool down.