Mercedes won't start

Maintenance/Repairs
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1

I am the original owner of a 1989 300 TE Mercedes Station Wagon, gas. It has 218,000 miles. It cranks fine but takes 4 or 5 tries to start then dies when put in drive or reverse. Does this when warm or cold. Any ideas as to what is wrong. I have changed injectors, plugs, wires, distributer.

2

The next thing to check is the fuel pressure. A weak fuel pump that doesn’t deliver the proper pressure/volume of fuel can cause both the problems you’re expieriencing.

Tester

3

I’ll check the fuel pump. I also hear that it may be a leaking fuel accumulator which appairently is located at the fuel tank?

4

You might also post this at a Benz forum, that’s where lots of users of old MBs can help you.

5

Correct, the accumulator is located directly next to your two fuel pumps and the fuel filter. The accumulator may help explain hard starts, inasmuch as it keeps the fuel system pressurized while the engine is off. But it’s not likely responsible for engine quitting once it’s running. But the fuel pumps and the fuel filter certainly could. When did you last change your fuel and air filters? Same for the fuel pump relay, located in the engine compartment on the passenger side firewall, directly behind the battery. While you’re up there, check on the overvoltage protection relay (OVP), located directly next to the fuel pump relay. It powers the fuel system, and bad connectors or solder joints or a failing fuse (there are either 1 or 2 fuses sitting on top of the OVP) can give all kinds of symptoms. If your ABS light flickers or stays on with engine running, it’s a classic OVP symptom.

Next in line after those things:

  1. EHA (electrohydraulic actuator), because it controls the fuel adaptation ratios;
  2. CPS (crankshaft position sensor), it tells the ignition system where the crankshaft is and when to fire the plugs for proper ignition;
  3. Fuel pressure regulator
  4. CTS (coolant temperature sensor), supplies a resistance signal to both the KE-Jetronic fuel management computer and the EZL ignition management computer so that ignition and fuel systems know whether the engine is running cold or warmed up, and adjust the spark and fuel accordingly.

After that, you probably get into expensive stuff (computer units). Do as Tester suggested and have the fuel pressure tested first. This is a DIY job if you have the tester with the CIS adapter, or a simple job for any knowledgable indy who knows the earlier MBz chassis like your W124. It requires testing the top of the fuel distributor and bottom, and adjusting the differential between top and bottom to about 0.5 bar pressure.