M117 4.5 Hard Hor Starting — 15–20 Minute Rest Period

I'm experiencing an issue with my car that's puzzling me. When the engine runs fine but then sits for 15–20 minutes before restarting, the car becomes very difficult to start. After several attempts, it usually fires and runs normally.However, cold starts and restarts after 30–45+ minutes of running both work without issue.Recent work completed:

• Ignition components replaced
• Injector trigger points serviced
• Throttle position switch (TPS) replaced

I'm trying to narrow down whether this could be vapor lock, a leaky injector, or something else entirely. Any insights would be appreciated.

W108 1972 4.5 USA

...check if the hotstart-device is working !

Hi Christian,
where is the hotstart-device?
Never heard of this...

Regards
Norbert

Correct - no such device.

@Nordfisch - any ideas on the issue?

Hi Tom <found your First name in your first thread>,
maybe you have a vapor-lock-problem.
Did you measure the fuel pressure with engine running and after shutoff?

One critical point in the future could be the short hose between pressure regulator and the damper. It tends to clogg. I saw it in the photo of your first posting.
Use a pre-bended hose like this one. Not available at Mercedes in Germany nowadays, but maybe you get one... there are alternatives, too. 


Regards
Norbert

edit: Try to get possible vapor out of the system by switching ignition on and off several times before starting.

 

Thanks

Also the picture was not of my engine - it was an internet photo but I will check my car and provide the engine.

I eventually can get the car started, but it takes some dozen + fuel pump activations, then it starts sluggishly then corrects. I read that four to five should be sufficent but this is not in my case.

Also I just purchased my fuel pressure gauge equipment and will verify.

Thanks for the pointers.