1Z Not Working? Troubleshooting Guide.

The 1Z engine came from an Audi 80 (year 1991) and was installed in a T2 van about a year ago, where it ran without any problems until a few weeks ago. The crankshaft position sensor was never installed.
Here's the problem: The engine won't start. The error memory is empty (except for the missing signal from the crankshaft position sensor). When trying to start the engine, no diesel is coming out of the disconnected fuel injection lines.
Subsequently, the pump was taken to a Bosch service center, thoroughly checked, and partially refurbished. No change. Then, the engine control unit (ECU) was replaced (it works perfectly in another vehicle). Afterwards, the throttle position sensor (due to a replacement speed signal) was also replaced, and all the wiring from the sensors and actuators of the engine to the ECU was checked. Again, everything was in order.
I'm starting to run out of ideas. What else could it be?

Are the valve timings correct?

Yes, they are fine. Everything was reset before removing the pump, and everything was reset again after installing it.

What was done to the pump? Was there air in the fuel system?

The pump is receiving power and drawing fuel when started, but nothing is coming out of the fuel injectors. The filter is new. I'm not sure exactly what was done to the pump. It was taken to a Bosch service center.

Have you tried starting it while it's on an incline? Maybe the starter motor isn't spinning fast enough.
Will diesel fuel be used in the ESP?
Compression OK?
Correct diesel fuel, not some kind of low-quality substitute?

Don't give up...

Serge.

The starter motor is spinning fast enough. Towing the car didn't help either (no fuel is reaching the injectors).
The compression should be fine. The cylinder head was recently rebuilt (valves were ground...). There are no signs of wear on the cylinder bores. I'll still measure the compression again, but it probably won't affect the lack of fuel reaching the injectors. The diesel is from the gas station next door.

Does the solenoid valve on the ESP actually receive power?
It's not that there are any hidden contact problems in the connector.

This allows you to determine whether the engine control unit (ECU) actually authorizes the engine start.

There are 12V applied to the shut-off valve.
One observation I've made is that when I turn the ignition on, I hear a clicking sound from the pump twice, with an interval of about 1 second between the clicks. It sounds like the flow control valve is hitting a stop twice. Other models don't do that.

chaerte wrote:

There are 12V at the shut-off valve.

Then the question remains whether it will open.
Test 1: Disconnect the cable and use a test lead to tap from B+ to the disconnector.
When the valve opens, it should make a quiet clicking sound.

If not:
Test 2: Measure continuity or resistance (estimated target values: not exceeding 10 ohms, or consult self-assembly manuals / I don't have one handy at the moment).

If resistance is okay:
Unscrew the part, temporarily remove the blocking piece, and try to see if it starts.
If present: Locate the burrs that are obstructing movement and remove them.
Of course, without any wood chips getting into the pump...

Quote:

One observation I've made is: When I turn the ignition on, I hear a clicking sound from the pump twice, with an interval of about 1 second. It's as if the flow control mechanism is hitting a stop twice. Other 1Z models don't do that.

"As far as I know, it depends on the MSG software. It's only when it suddenly stops working with the same MSG file (even with the same engine temperature) that there's likely a problem."