1990 300SL hard start warm
 

Currently have a 91 300SL with the 104 CIS engine. Seems to start fine cold, but after hot soak it will start-stall and then have a long crank and sputter for a bit before working properly. Thought injector leakage or bad check valve. Connected to upper chamber pressure, holds fine after shutoff. Can't connect to lower chamber due to poor positioning of the test port, but when it stalls the pressure on the high side remains okay which makes me think that there isn't low side leakage either.

Though maybe vapor lock from bad accumulator, but that tests okay too. Disconnecting EHA doesn't help, nor does IAC. Looks like cap/rotor/wires are new, as well as fuel filter. I'm getting a little annoyed, can't find any recommendations on the forums for testing anything I hadn't already gone through.

Any help is appreciated.

What are you running for fuel?

Gilly, not sure, it's a customer vehicle. Thanks for the brain jumper though, the guy said he hardly drives it, probably bad fuel of fouled plugs, I'll check it tomorrow and post the fix when I find it.

So could be old gas, I was mainly thinking of how I've been having trouble with my cycle (07 K1200Gt) run this summer, I do use gas with ethanol in it, and pretty sure that the ethanol has been my problem. Yeah something to think about. Or else crud on the back of the intake valves, you could pull an injector and take a peek.