380sl wont start again.. Please help

[Tony1628]

I have a 85 380sl .Approx. 5 month. The car won't start. It will start for about 2 sec and then died. I tried for a few times. It got worst till it just cranked and nothing happened. The next day, the same process again. Approx. 2 month ago. (amost dead of winter... 32 deg to 40 deg.) The car somehow started like nothing ever happened. In the meantime, I changed out the cold start valve, idle control valve and some of the vaccum lines. It has new rotor, cap, wires, coil, fuel pump, filter, and spark plugs. Well, it happened again this morning, I couldn't get the car started. same problem... PLease help.. did a lot of search on the forum and can't seem to get what I should look for.
THANKS!!

[lino]

Does it have gas? I mean is the guage working properly for sure? Is it old gas?
Man that's weird.

[Tony1628]

Gas is fairly new..
Here're what I did:
-Checked the ignition timing.. 20 deg BTDC. (don't know what the right timing is)
-Took the vaccum hoses off the thermo vaccum switch and plugged up the hoses with golf tee. no effect
-Took the cable of the frequency timing valve.. no effect.
-Checked the voltage off the cable from the Cold start valve. read 0 volt.
attached a +12v to the cold start valve.. no effect. (Thought one of the thermo sensor is deffective cause a 0 volt to the cold start valve). don't know which sensor the cold start valve is related to.
- check the two temp senors on top of the thermostat. The one on the right read about 1k resistance and the one of the left side read infinite.. (right - switch the aux fan, left - temp gauge)

I am running out of ideas...Please help...

[Tony1628]

The fuel pump is less than 3000 miles. I checked it along with the relay and seems to be fine..
The ignition system. Everything was replaced (wires, plugs, cap, rotor, and coil)

[Q]

While someone is touching the fuel pump, start the car and make sure it keeps running. It's possible that you have a fault with the relay that would make it intermittently run.

[Tony1628]

All of a sudden, the car started again... It start extremely rough.. barely 100 rpm. it lasted about 15 sec. then stalled. I restarted and same thing..after the 4 tries, the car started.. I am totally lost .. no idea... I did replaced the fuse on the over voltage relay.. don't know if that has anything to do with it.. because I took the relay out and the car started fine.. no idea whatsoever.. I am afraid to drive the car now...

[Roncallo]

I assume you did check for spark as someone else had asked?
Did you check fuel pressure? Special presure gage is required.
Did you check your fuel filter?

John Roncallo

[Tony1628]

I think I got it.. it is the over voltage relay.... so far so good after I replaced the 10 amp fuse which was blown...

[Tony1628]

actually i pull out the ovr.. the car won't start.. so it had something to do with cold start