This happened twice today, once on the way to work, once coming home. Slowing down from about 50 mph to make a left turn, the engine stalled. No warning, it just quit. Restarted easily and ran fine for the rest of the drive.

Here's what I've replaced in the last 14 months and 16,000 miles: Head gasket, O2 sensor, all new copper fuses, voltage regulator, plugs, wires, cap and rotor, fuel injectors and seals, fuel filter and accumulator, OVP relay. The car is my daily driver and has always run great with a normal idle speed and it starts better than when I got it. It now has 152,000 miles.

Any ideas what I should check?

Edit: I just pulled codes from the diagnostic plug and the only one I got was for the air injection system. I unplugged the air pump about a year ago because it was noisy when cold but it's never thrown a code before and I thought it was only for emissions anyway.

This happened to me on the '89... dying fuel pump relay. Which for you should be the MAS relay like my '90.

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I'm not a doctor, but I'll have a look.

'85 300SD 245k
'87 300SDL 251k
'90 300SEL 326k

Six others from BMW, GM, and Ford.

Liberty will not descend to a people; a people must raise themselves to liberty.[/IMG]

I once had an 83 380sel that would stall while running - no other symptoms. It would restart easily and I couldn't figure it out. I checked fuel, battery ground and probably some other things I can't remember. It finally died on the interstate and wouldn't restart. Turned out that the coil died.

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07 E350 4Matic wagon, 06 S430 4Matic, 99 SLK 230
retired W210 (x3), W124, W126

Check the fuel cap, on the tank .If its has a faulty seal, its loosing pressure. And as post above from brooktre .Earth points must make a good contact to the body .

The fuel system does not pressurize the fuel tank. Ideally the pressure inside the tank should be the same as the surrounding atmosphere or at a very slight vacuum to keep fumes inside the evap system.

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

So do you mean instead of a regular fuel pump relay I have to get an MAS relay instead?

Depending on the year model, the MAS relay *IS* the fuel pump relay. You haven't told us what year your car is.

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Sorry, it's a 1991, and to respond to what someone said, the coil has been replaced.

Did this happen with foot off the accelerator and engine at about idle?

If so - my vote is for the road speed sensor

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1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

No pressure ,or no vacumm , have it your way. But it will run poor ,and even stop , with a bad fuel cap seal.. May be i said it wrong .But if no sound from it as you lift off the filler cap ,the cap will need replcing ..

I was on the brakes, setting up for a turn, so yes, foot off the gas. Not sure what the engine speed was but I doubt it was fully back down to idle speed.

Again, no. The only reason the cap is sealed in the first place is for emissions (preventing vapor from escaping) and to minimize moisture ingress due to temperature fluctuations.

The tank has a vent to prevent building pressure and has a valve to prevent vacuum. You can remove the cap and drive around all day and have no impact on how the car runs or drives. On a newer car, you can set a check engine light if the purge valve checks for vacuum at the cap (most cars run very slight vacuum to prevent fumes escaping), but this has absolutely no effect on how the engine runs.

All fuel pressure is created by the fuel pump. It doesn't push air in the tank to do this. Not sure where you're getting your information, but I'd check the reliability of your source.

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

I know you posted above that you replaced the distributor cap and rotor, but have you pulled them off to check their condition since this problem has been going on?

Additionally, is the OVP you installed used, or is it brand new? If it's a used one, I'd suggest replacing it with a new one. When they get flaky, they can be maddeningly difficult to troubleshoot.

If you're handy with a soldering iron, it may be well worth your time to take the cover off the MAS relay and look for broken solder joints on the pins of the circuit card and the pins of the relays.

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

The OVP was new. I haven't checked the cap and rotor but I will. I'll probably also order a MAS relay too.

how to remove the MAS CONTROL RELAY mercedes w124 ?? It looks simple but I am unable to get it pulled.