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Q: stalled car on 1990 Mercedes-Benz 420SEL

car stalled while on the road. plenty of fuel(half tank) turns over fine. no prior problems. Any suggestions or ideas
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two things .1st fuel pump relay switch /2nd overload protection switch .there both on the inner firewall inside the hood area fprs is blk and the ops is silver with two fuses in a clear cap .theres a vent cap on the gas cap too try taking it off next time it stalls .and see if that does it ?if it does replace it .?
It's hard to say what is going on without a diagnostic check. For an engine to start it needs fuel and ignition, so check the fuel pressure and spark to the cylinders to see which is not working, then diagnose accordingly.
My 420 sel did the same thing. I had the fuel relay gauge changed and now it is fine.
The OVP relay mentioned here is not part of your engine stalling, it supplies voltage to the idle control relay and the idle air valve (relay inside car passenger foot well) valve in front of air intake (6inch cylinder) If the valve fails its default is open so you rev high, if the relay fails you also rev high, take the relay out and disconnect valve you rev high but still start. First thing, turn on ignition, can you hear from under car both fuel pumps energize, if not then release fuel pressure by slackening the fuel line to fuel distributor (under pressure be careful) then try again, if not then it could be the fuel pump relay on firewall marked kickdown and next to relay marked klima (AC), if pumps are working check for spark, if weak spark coil is probably ok and you need to look at the ignition control module, drivers side front of car of fender well. If u like e mail me, I have spares I can send u and will assist in greater detail.
I had a 320SE that was doing the same thing.
And I took it to the Service center, they checked it
and found it to be a fuse linkege, I can't remember
were it was located, but they replaced it, and the problem went away. I drove it for another two years.
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