1996 W210 E300d stalling when warm
 

Hello!
Thanks to all the contributors to the many threads I read trying to solve my issue!
Problem: Engine stalls when after about 20mins of idle on a hot day. When trying to restart, it almost, almost, almost, almost, nope not gonna start. It acts like low fuel pressure. What a few hours for everything to cool off and bam, fires off almost instantly like normal and purrs like the turtle it is. The car is white with beige interior btw.

Actions:
I decided to throw a new OEM K40 at it that I bought here. No love. Zero change in results. I hear the SOV and everything clicking but I'm wondering if the solenoid in the SOV has become weak and partially closes? Is my IP crapping out?

Here go's:
Last summer, peak of the heat here in North Carolina I'm on the road visiting customers. Sat idling, AC cranked for over an hour while on a conference call when it just stalled. The ignition and everything stayed hot but engine died. Tried starting for another 20mins. Also tried while powering up my inline pump from the time before I replaced all soft fuel lines with OEM including the SOV o-ring. No start. Wife to the rescue and back I came the next day with the trailer. It fired right up and went onto the trailer. After that it sat until the fall when I went back after it and started driving it around for local trips around town. Problem never resurfaced. Temps started rising in the spring and on one hat afternoon it died just before I could throw it in park t my house. That was a sign.

Sounds like cps but not sure if applicable on 96 diesel. Whatever it is sounds temperature dependent.

Hmm. I'll have to look that up. Thank you for the suggestion! I'm not sure if it has a cps or not. I've had them fail on Volvos and older Saabs but that failure typically results in absolutely no fire. When my problem is acting up which is now everytime it gets warmed up it quits and then acts like it's so close to starting but just won't. Let its sit and cool and it fires off instantly so I've ruled any kid of air leaks. I mean even after sitting for weeks it pops off immediately.

Well I'll be! Just found a thread on a w202 with OM606 and very similar problem and it indeed was a failed CPS. Guess that will be the next wad of cash I throw at this problem. Will report!

Good luck!

I had a w210 E430 (gas) that was having some related issues. once running it was fine. Starting was the issue. The starter would engage then stop (even though the key was still engaged in the start position.) It was random. Chased a lot of things, turns out there was a service bulletin for the greasing the starter gear with antiseize. I never did that, but I degreased the flywheel and brused antiseize on it through the ports. It helped, but did not cure. I have an 8 page thread about it on Benzworld. Doubt this is your issue, but thought I'd share in case the CPS doesn't solve it....even though it sounds more CPS related.

Update 8/12/23
I'm now 2 parts in with the same issues. Replaced with OEM Spec 1996 K40 relay
Replaced Bosch 0228 CPS sensor and just when I thought I was out of the woods this morning after about 45mins parked AC cranked she stalled out. No CEL no blinky mirror lights. Just won't restart. It tries to restart but only makes it 80% of the way spitting and stumbling and almost running. I have no doubts I could go back in 4hrs and have another 30mins before it dies again. I have a facet pump in line under the hood that I installed years ago to solve a leaky line problem enough to get me home. I replace all the soft lines under the intake manifold along with the Fuel shut off o-ring and the copper crush seals on the injector outputs on top off the IP.
Next steps
1.Pull the fuel supply line post inline pump to make sure this isn't a fuel flow issue before the IP.
2. Check voltage at Fuel shut off valve and make sure the it's reading correct from the k40.
3. Isn't there a fuel temp switch in the head that's only job is to cause a failure? I need to find the resistance specs to test the switch.

The conclusion:
It's fixed! Another basically free fix.
I pulled the crossover intake tube off so I could get access to the Fuel shut off solenoid plug to check for voltage. To my surprise it was intermittently blinking at the same time I moved the harness around. Ahh Hah! About 4" down the harness from the fuel shutoff plug I found a previous owner repair. They had soldered a wire back together and did it horribly. It was coming apart. They also failed to insulate the repair and that caused it to rub 2 of the 4 wires through but just barely. Re soldered, insulated and plugged it back in. Done.

Congrats on the fix and thanks for sharing!