BenzWorld Junior Member
Date registered: Jun 2016
Vehicle: 1968 250 SE automatic
Location: Queensland Australia
Mentioned: 0 Post(s)
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Many thanks for your response. When the car was bought many years ago it was not in good condition!!! The engine was in pieces ( large pieces), in the boot, the injector pump was separate, still with the fuel pipes connected. The engine was subsequently completely reconditioned and re built and is now considered in good shape. The control mechanism on the injector pump was not touched but the individual piston had to be "unstuck" and re installed. We certainly have disconnected the cold start injector valve and even plugged off the fuel line to it to try to improve the running. No change was noted. We have also checked the pressure at the fuel line to the cold start valve and had 20 psi, the same as the fuel pump pressure. 19psi is the only pressure level we can find mentioned in the workshop manual and that is for the fuel pump itself.
What should the working pressure be in the pump? Is that pressure controlled by the pressure relief valve in the return line? It would make sense to have a pressure in the pump at some value less than the pressure output from the fuel pump. If 14psi is the working pressure, we can adjust the relief valve to suit.
At least you have given us another line of attack. Thank you.