I realised the other day that it has been over a year since I started up the motor on my 230sl. I had just gotten a second set of Bosch spark plug cables to replace the 90deg connector on the #1 cable and get rid of the carbon wire on the coil. I thought I would fire it up to see how the car would run with them hooked up.
Because the instruments have been removed to paint the dash I hooked up sedan oil pressure gage to block off the line.
I hooked up the battery, turned on the ignition, and instead of hearing a high pitched whirr from the fuel pump it made a sickly growl that increased and decreased in pitch. I took off the fuel return hose under the hood and no pressure or flow at all.
I'll have to dig around through my spares, I have a late style pump somewhere that I think may still work.
