1988 560SL With Warm Start Problem

[nhdoc]

Hi,

I have a 1988 560SL with 109K miles on it which exhibits a problem starting on the first try if it is left to sit for 1-4 hours. Cold starts are fine and hot starts also are fine if restarted under 1 hour from shutdown. In the 1-4 hours range the car will sometimes seem like it is starting - the engine "catches" and revs up but then dies and will often start on the next try without incident. Sometimes it stumbles a little after that second try but will usually stay running and smooths out after 1-2 seconds.

I have replaced the fuel accumulator and check valve on the second fuel pump to eliminate the possibility of leak-down at the source, but that did not cure it. I've also replaced the coolant temp sensor. Any suggestions of what to try next would be appreciated. I don't have a fuel pressure gauge so if that's the next step I guess I have to buy one.

Thanks,

Marty