My '85 190E (US 8v w/ 88K mi) rough started one evening , then cranked but wouldn't start the next morning.

After going through the published troubleshooting routine to check the OVP relay, ignition (TSZ) component continuity and resistance values, and any obvious vacuum leaks without finding anything out of spec, I entrusted (i.e. towed) it to a local import shop that sells a lot of MBs and BMWs.

I had interviewed the owner, and he was confident the tech would find the problem. After three weeks and "a lot of work on it" they told me the timing chain was bad. Three weeks to learn this? I had seen enough and towed the car home.

To confirm their diagnosis, I lined up the timing marks at the distributor and the cylinder head to see how far off it was. It was dead on. I lost confidence in their opinion.

Concerned that there was bad fuel in the tank, I wanted to drain the 3-5 gallons that remained there and replace it with fresh fuel. I figured I'd disconnect the fuel line in the engine compartment, and use the fuel pump to deliver the gas to a container through some vinyl tubing.

I turned the key to excite the pump, but turned too far into the "start" position. THE MOTOR STARTED RUNNING WITH THE FUEL LINE DISCONNECTED.

It continued to run (for the first time in two months) at a smooth idle while the gas flowed from the tank into a five gallon bucket instead of the fuel distributor. (Thank God there were no errant sparks).

After adding some fresh fuel, and reconnecting the fuel line, the original problem remained. Now, I had to re-create the "No Fuel Line" scenario to see if the results would repeat. They did. The car starts easily and idles smoothly as long as the fuel line is disconnected from the FD. Otherwise it won't start.

I assume that the motor is running off of vapor drawn through the recovery canister or more likely fuel drawn through the return line.
I also assume that the timing chain is not as bad as it was "professionally diagnosed" to be.

I hope to start troubleshooting the CFI soon. I did notice that the plugs are getting wet with fuel, and I assume that timing and spark are adequate due to the "NFL" running condition. There does appear to be some fuel accumulating below the air sensor plate. Some dripping can be seen there.

Apparently fuel is getting delivered, but not under conditions to ignite. Perhaps its a fuel/air issue, but you would think that if it starts and runs on the vapor/return, that I could at least get a rough idle out of it under normal starting conditions.

Also, the injectors shouldn't be opening without fuel pressure, so is the fuel being drawn in through the intake?

The shop manual is unclear on a test procedure for the return line. Perhaps a shot of compressed air would determine whether it is clogged. Anyone checked their return line with this technique?

Any insights into the KE II Jetronic tests without the use of a scope would be helpful. Also, has anyone had any luck using a dwell meter on the TD terminal at the diagnostic socket?

I'd appreciate the insight.

Recommendations on sources of rebuilt fuel distributors may also be helpful.