First to moderators, please do not kick this post to W11x subforum. Yes, I do have a W111 but it has a 230 engine from an SL and I need the expertise of the SL people. That's why I subscribe as a full member to the Pagoda forum without owning an SL.
My problems started maybe a couple of months ago after driving over 30 minutes and usually at high rpm. The engine would lose power and if coasting or coming to a stop it would stall. It would start immediately but the power loss and stall would persist. After cooling everything would go back to normal, for another 30 minutes.
I spent hours reading the forums posts. I verified the "flower pot" return issue by filling the tank and eliminated it. I found the distributor points to have, one a crater and the other one a deposit and replaced them, changed through red and blue distributors until I reverted to the original combination and 39 degrees dwell angle. The problem is still there.
I moved to fuel, I checked fuel delivery at the CSV and on the return line at the tank and found to be about 40 sec/ltr. I pulled a spark plug and it was charred light brown so fuel starvation? I quickly concluded that the fuel filter was clogged. It was indeed brown from rust deposits and I changed it.
The problem didn't go away, 40 seconds at the CSV. I concluded that the pump is letting go of the ghost so I bought a generic 140 GPH 14 PSI pump.
Replaced the pump, still 40 seconds at the CSV.
Bought another fuel pressure gauge, 15 seconds at the pump, 40 at the CSV. I disconnected the fuel line before the filter pot and got maybe 30 seconds. I blew compressed air in the line from fuel pump to filter pump forwards and backwards, I wasn't happy so I checked the integrity of the fuel line under the car. I found a serious strangulation probably from a smart technician that placed the lift pad under the fuel lines. I cut off the flattened part and replaced with rubber hose, progress. 15 seconds at the fuel line before the filter, still 40 seconds at the CSV. Frustrated I realize that the original pump may be OK, I put it back and put a new fuel filter.
At the CSV 10 PSI, 15 PSI with the return line clamped but 40 sec/ltr consistently. At least I know that the pump and the overflow valve after the IP are OK.
Logic tells me that the filter + filter pot + the tee + CSV fuel line could be the culprit.
I could remove the filter from the circuit and try it again but the filter is supposed to be there even if I would put another inline filter somewhere. The original filter is designed for flow and pressure to be there before the IP.
From reading all these posts, I am concerned that vapor lock due to insufficient flow is the cause for power loss and stall.
I can insert a tee at the CSV and plumb the fuel pressure gauge inside the car to read the pressure when the power loss occurs although I'm not sure if vapor lock in the IP would show as a pressure drop upstream of the IP in the CSV.
Anybody has any ideas?
Thank you.