88 560sl Hot Start Problem
 

Hi everyone. My 88 560SL has hot start problem. I changed the accumulator as fuel pressure was leaking down to zero and the car would not start when hot. This car has had recent valve job with new intake seals, hoses, etc. Injectors were replaced. Fuel pumps, filter, and fuel pump relay were previouly replaced. Recently replaced the EHA and fuel distributor. Fuel pressure is at spec for system and lower chamber. EHA amps are set to 0 plus or minus 1 at hot idle and duty cycle is approx 50%. Oxygen sensor is also new and is fluctuating properly. Mixture control appears to work OK. Temp sensor ohms out OK. Now, when hot it takes about 10 seconds while holding throttle down to start, "if" the car has been setting for a few minutes. Fuel pressure drops instantly to 50 psi when I kill the engine. Car will restart perfectly at this time. However, the fuel pressure slowly leaks down to 30 psi over about 30 min and will hold this pressure all night. The cold start valve does not leak. I substituted another fuel regulator (used) and it did not help. Neither appear to be leaking. I have not pulled the injectors as I do not have the test equip to check them, but I would think it unlikely that the new injectors are the problem. First question- Is 30 psi the correct pressure for the accumulator to hold. Second-is it likely that the fuel pump check valve(s) would leak down to 30 and hold at that level. What about vapor lock? I would appreciate any suggestions.

I've got the same problemn and.....
 

I was speaking with a tech about it he had said that it could very well be the check valve (I ordered one today). His logic is that when cold, the cold start valve compensates and the car will start. When warmed up, the cold start valve is defeated but if the check valve leaks there won't be enough gas in the accumulator under pressure to start. Mine does exactly that-starts everytime cold, but if I take even a short drive and reach operating temp, i'm likely to have to spin the starter several times to get it to start.

It's a $20 part-wouldn't that be great if that was the fix?

JB