300 SEL Problem
 

I have a 90 300SEL and this spring when I got her from storage she started right up and ran smooth as glass. I let it idle for 10 minutes or so and when I stepped on the gas she stalled and would not start again. I let it sit for an hour and tried again, started right up, again when I stepped on fuel pedal it stalled. I cranked her over and after awhile it would go but same issue. I have put fresh high test in the tank and it still has the same symptoms. So any ideas? Someone suggested cold start sensor, I don't know run perfect when I put it away. It has about 120,000 klm or 75,000 miles.

Sounds like lack of fuel.

Take off the air cleaner assembly and push down on the air flap in the CIS unit. It may be stuck.

Next, Check your fuses. Also, rotate them in the clips to reduce corrosion resistance.

Next, remove the fuel pump relay and jump pins 7 and 8, to see if the fuel pump runs properly.

FPR or pump?

I will try all that and let you guys know if something works.

How long was the car sitting stored?

The fuel system may have gummed up some of the injection system.

For the winter, I put stabilizer in it beforehand, I have been storing this way for years w/o any problems, until now of course

Get a fuel pressure gauge and watch closely and record the readings as the car starts, warms up, and eventually stalls. You will then know for sure if you are chasing a fuel pressure issue or not.

You could just as easily have a vacuum leak that opens up when the car gets warm, some heat related electrical gremlin, etc...... The most likely candidate is a fuel issue, so start with a fuel pressure test.

Hot engine starting problems are also and mostly related to a leaky old accumulator .
mak
300se