i was also reading some threads and someons had a similar problem but with a higher rpm. turned out it was the ovp relay.
but as i mentined before, when i released the pin on the pressure regulator, it shot up and the gas hit me in the face with a bang.
thanks

I forgot to mention when working with any component in the fuel system ie fuel pump etc depressurize the system or gas will spray in your face. I thought you would automically depressurize the system since it seemed pretty obivous.

__________________
1986 300SDL, 211K,Dealership serviced its whole life
1991 190E 2.6(120k)
1983 300D(300k)
1977 300D(211k)

but is the gas system supposed to hold that much pressure even when the car has been off for a while?

When you shut the car off not all the unused gas in the system goes to the tank some of it stays in the fuel system in the engine compartment as you found out today. My 190E that doesnt run at all, had some fuel still in the pressure regular and at the eha unit even though the car hasnt ran in a while when I removed them.

__________________
1986 300SDL, 211K,Dealership serviced its whole life
1991 190E 2.6(120k)
1983 300D(300k)
1977 300D(211k)

>>but as i mentined before, when i released the pin on the pressure regulator, it shot up and the gas hit me in the face with a bang.
>>

What did you take the regulator off for ??
The test for reg is done on the car. The test I mentioned is for a reg leaking diapragm.

If you pass that test, then you do a Fuel Pressure test..this will test the pump/s and the regulator for spec.

Car at idle with vac hose to reg connected:
3.2-3.6 Bar
At idle, vac hose disconnected :
3.7-4.2 Bar
System pressure after at least 30 min wait :
No less than 2.5 Bar.

All these specs are taken right at the test port valve on the fuel Rail..you do not take the Reg off for any of these test [ uncluding the other quick test I gave you]
..but , if you do have to remove a reg, you of course release the system pressure at the test port valve....and turning the engine off too would be a good idea..
If the pressure is too high , then the reg is not doing it's job and that will cause the rich condition. This can aslo be caused by a vac leak on the vac line that controls the regulator.
This HFM system is full electronic, so the Fuel Pressure HAS to be to spec.

i know where the port is on the fuel rail, you can release the pressure from there. but i dont have the tool to measure the pressure on there.
is it something cheap i can buy?
thanks

They are not expensive..I would just go to a discount auto store or Harbor Frieight...

You do not need a commercial quality one.

Fuel Pressure Test Gauge.

i think the auto parts store lets you borrow any tool for free, so i am gonna loan it from there.
so i just need a fuel pressure tester, and a lambda tester?
thanks

I tested the vacuum pressure yesterday, it turned out it was fine.
but one thing that is abnormal that when i first start the car when its cold, the rpm is pretty low, 1000 in park, 700 in drive.
but when it warms up, the rpm goes up to 1300 in park and 900 in drive.so it does the opposite of what its supposed to do.
any ideas?