1988 300SEL trouble starting/doesn't stay running
 

hello all,

I've got a 1988 300SEL that has been very well maintained despite the 260k miles on the clock. Ran well, until recently. Now it won't start, and once it does come to life it will drive very roughly for five feet before shutting off again. So far, I've replaced:

air filter
spark plugs
plug wires
cap
rotor
fuel filter (next to fuel tank)
ignition coil

Any ideas on the next route I should take? I've owned diesels for many years now, this is my first gasser benz.

Sounds like a fuel delivery problem. It's worth checking the fuel pump relay, it's a common failure item. Do a google search on the issue and you should find several different articles on what to look for and how to test it.

That was my first thought too. I had erratic stalling problems with my 88 300ce M103 until it finally quit. Dealer installed new FPR. Problem solved for about 4 years.
Started stalling erratically again about 5 years ago. Dealer replaced ignition wires, rotor & coil & it's been running fine ever since. So, go figure. Same symptoms; different causes.
If it regularly starts but quits immediately, could also be a clogged filter in the line maybe? Hope it's not the fuel distributor. That's a pricey part. I had a rough idle when I first bought the car and the dealer switched the fuel distributor with one from a yard 190E2.6. He told me I'd eventually have to replace it. That was 16 years ago. Knock on wood. ;)

Pull MAS relay - jumper ports 1 & 2 - if car starts and runs - you need a new MAS.