1965 230SL power loss/hesitation when hot

[seeMIL]

Help please if you can.
I have recently started experiencing my 230SL hesitating and losing power when warmed up and on the open road at mid to high revs.
The engine and fuel pump were rebuilt 4k miles and it has been running beautifully until now. I have also been running a 123ignition distributor.
I initially checked the fuel filter and replaced it, no change.
I have since concentrated on the electricals, systematically swapping from my other cars the coil, leads, rotor, cap and finally replacing the original distributor. No change.
I get the impression it’s electrical by the hesitation but maybe it’s fuel?
Any guidance would be useful. Thanks in advance.

[rwmastel]

If you are a DIY person and have a pressure gage, you can check your electrical fuel pump.

Disconnect the rubber return line at the tank and secure it in a container, turn the ignition on for 30 seconds, and measure the volume output in that time.

Connect it back together.  Then in the engine bay, connect a pressure gage in-line between the big fuel filter and the mechanic injection pump. (I believe that's a rubber line.)  Run the car and check fuel pressure.

You're a Full Member, I assume details of these tests are in the Tech Manual.

Let us know results.  You need to deal with facts/data gathered by testing.  Sometimes the process of elimination is necessary.

[seeMIL]

Thanks, I’ll report back my findings 👍🏼

[waltklatt]

Follow Rodd's suggestions.
What do the spark plugs look like?  Lean, sooty, etc...
That's not in your description.
Walter
1967 220SL diesel
1969 280SE
2003 Beetle TDI
2005 Honda Element

[rwmastel]

You said you have a 123 distributor.  There are members here very experienced with that system.  I'm sure they'll have questions, but check the Tech Manual on that in the meantime.

[ja17]

Sounds like fuel starvation. How is your fuel tank?

[seeMIL]

Hi all thanks for the support. I found the issue today, fuel starvation as suggested. I was checking the pump and noticed a suction filter had been previously installed on the tank outlet. I removed the filter element and the car is running super sweet. Thanks all for your help. 👍🏼👍🏼👍🏼

[rwmastel]

... a suction filter had been previously installed on the tank outlet ...

Maybe for a good reason.  Was there rust in the filter?

[seeMIL]

Hi. No rust, just clogged up. Probable never been changed for a long time

[rwmastel]

I'd put a clean one back in-line to protect the electric fuel pump.  There is probably rust in the tank.  Common.