Our friends at Autoshack have reached out to our restoration workshops to look into a few issues on this 1988 Mercedes 300SL. Our technicians John and Will have been working their way through the cars original ‘K-Jettronic’ fuel injection system to get the classic Mercedes running.
‘The car came in with poor running and no idling. The plugs were removed and cleaned and noted 3 of the plug leads were broken (the caps had come off the leads). The car was they tried and the vehicle fired up but wouldnt idle. It was then checked to see if there was fuel at the metering unit. It seemed to have good fuel pressure. But no fuel was getting to the injectors. The pipes to the injectors were cracked and the fuel pump operated to see if it was possible to get fuel to the injectors. The fuel was a brown colour so the fuel was drained from the tank and fuel filter was replaced. New fuel was put into yhe tank and the system bleed. The idle control valve was cleaned and the car started. The mixture was then adjusted and the car started. It idled nicely. Further setting up will be done when hot.’
‘Begin to diagnose no start with John, 10L of fuel in, bleed through bosh k-jectronic system and injectors find that it’s not getting fuel up properly and fuel pump keeps running all the time, remove fuel pipe to fuel pump to drain, and remove pipe completely and poke rod around to see if there is a blockage, remove fuel pump filter and swirl pot assembly, remove fuel filter from assembly and find it has bits rattling around in it, replace with new filter, remove fuel pump from assembly. Bench test fuel pump to see if it works, flow test fuel pump to see how much fuel is flowing per minute, reassemble fuel pump assembly, refit to car, new terminal on fuel pump wire, 10 litres of fresh fuel in car, bleed k-jectronic system with John, car starts but won’t hold an idle. Remove plugs and dry off as they are wet from fuel, bleed through k-jectronic system and injectors again, remove slow idle coltrole valve and clean out and unseieze, refit slow idle control valve, adjust idle screw on throttle butterfly and car runs and idles.’
