starts on second try
 

1990 300te
when turn ignition, starter turns over but no start
when turn key back to start then again, starts perfect
always on second try

what can i do to make it start first try?

is it the pressure on the fuel rail?

has anyone ever experienced this before?

My 98 300SE does this when it is warmed up. If it is cold, it starts first time every time. If it is warm it starts second time 80% of the time.

There's an easy way to determine if your problem is being caused by fuel pressure leakdown (I'm guessing it is). Before you crank the engine, cycle the key on and off once or twice. This will build up fuel pressure. Then, crank it over and see what happens. If it starts normally you'll know you've got a leak, either internal or an injector(s).

The problem of the leak is not so much because of lack of pressure as such, because it will build up immediately when turning the ignition key.

The problem is because while the fuel system is not under pressure and the engine and/or the ambient air is hot, it will allow fuel to evaporate inside the system and build up gas bubbles, which it has to get rid of by cranking and resting.

But still the reason is the fuel system loosing pressure, not necessarily through an external leak, but more likely due to an internally leaking fuel accumulator (next to fuel pumps) or because the check valves at the output of the fuel pumps are not holding the pressure.

Could be valve stem seals too. Can you check the spark plugs?
Dan