Ok, I'm about to loose it on this '97 E300. I bought it as a wrecked runner - was a friend's daily driver till the wreck, then it sat for 3 months. When
I got it from him it fired right up - but as it had no radiator I only ran it a couple of minutes to pull on the trailer. It started a couple more times, then ran rough and hasn't restarted.
I've eliminated most of the usual problems as detailed in this thread:
1997 E300 still no start...
I've now got a 32oz jug of fuel under the hood with the supply hose to the fuel heater going to it. In about 2 sets of 30 second cranks I can suck down most of the 32oz. Fuel is flowing WELL.
I have confirmed the fuel is flowing from the SOV into the injection pump. It's flowing out of the injection pump return.
I have video of the rack going to almost full throttle as I try to crank:
E300 injection pump rack movement - YouTube
If I remove the lines from the delivery valves I get some pretty good squirting after a little cranking. Initially you get foaming, then the squirting. With the lines reconnected there is not enough flow to fire the engine. In fact, disconnecting the lines at the injectors and cranking yields very, very little flow. The lines are not damaged appearing... Here is a video of the delivery rate at the pump outlet:
Fuel delivery - YouTube
I removed the return line banjo bolt / fuel pressure regulator, and can easily blow through it. After reading on here that this is supposed to hold the delivery pressure at about 1 bar, this seemed suspect. In a lathe I machined the metal away around the staked in ball, and dismantled the valve. It has an amaazingly light spring that pushes a plastic plunger against the seat. There's no way this could regulate pressure in the 1 bar range unless the hole through it is enough of a flow restriction to raise the pressure that way.
Is there any type of internal filter screen in the injection pump?
How could I have flow through the injection pump body, and nothing making it out of the pump?
Can you come up with a scenario where all the delivery valves would suddenly fail?
Please help - this is driving me mad!
Thank you!