'85 500SL Warm Start Problem

[sublettm]

My father just gave me his '85 500SL. Shortly before he handed it over to me it started exhibiting problems starting once warm. In the past week we have replaced the fuel filter, pump, and accumulator. The problem still exists. We also swapped out the fuel pump relay...same results. I am inclined to believe it is fuel injectors leaking down. Is there a way to test this theory without taking the shotgun approach by replacing all of the injectors?

The car will always start but it is simply harder to start when warm. Any advice will be appreciated.

[Frank Reiner]

Look to the fuel pressure regulator (FPR). It is built into the fuel distributor (FD), and has a hex cap on the end. The device contains both the FPR and another valve called a push valve. The function of the push valve is to hold system pressure in the FD at a level just below the injection nozzle check valve opening pressure. A leaking push valve will cause the symptoms that you are experiencing. The FPR/push valve can be removed, and the o-rings which are the seals renewed.

[sublettm]

Thanks. I'll give this a look this weekend.

[meltedpanda]

yes , good advice, checking rest and running fuel pressures may be needed