90 300E wont start!
 

Hello all, long time lurker so I decided to post:

Here is my dilemma: 300E ran fine, warmed up. Parked in driveway, back in one hour, engine turns and cranks and starts up for 2 seconds then dies, then crank and crank. No start. Towed to shop. MAS control unit gets resoldered due to cracked joint, engine runs fine for 1/2 hour then next morning, no start. Replaced OVP, nothing....starting fluid gets car to start and idle for 2-3 seconds. Pump get 85 psi. 2 months ago new fuel filter, caty, and o2 sensor. Does anyone have any suggestions? I know im getting spark because it did run for a bit, thought the problem was solved but alas...no success. Do I now look at the FD? Give me something to go with here.

Thanks for your help!

fuel injection system?
 

I'm having starting/running problems right now too. Though it was fixed with the installation of a new distributor cap, but "problem" returned a week or so later.

Problem is when started, engine would die immediately. Learned to heel-n-toe the accelerator pedal to keep the RPMs up between 750 and 1000. After getting on the road, the engine would (sometimes) run normally. Well, it would run fine, when moving. But, when slowed down to idle speeds, it would die most of the time, sometimes while moving, such as when backing out of a parking spot. Very frustrating! I'm getting pretty good at operating this automatic car like it has a stick shift, (going into neutral at stops, braking with the left foot, keeping the revs up at idle speed or slightly above, etc.)

Asked a fellow at work yesterday...described the symptoms...and he immediately said it was the fuel injectors. He's not a MBZ guy, but understands engines.

This is with a M103 engine. Not sure it is applicable to yours. Worth checking anyway.

The injectors i might check last, in that it ran smooth as silk day before yesterday for about 1/2 hour. Today he is checking the FD to make sure fuel is getting to it and then see about the injectors. I am suspecting the FD is the culprit, but clasping my palms. i did see some threads about the coil and the crankshaft position sensor, but the FACT the engine ran smooth for 1/2 hour leads me to believe otherwise.

Has anyone had this problem and solved it? Help is always appreciated.

Thanks!

Personally I'd probably start with the Crank Position Sensor....

My vote is for the CPS.
 

However, it could be a lot of things. Good luck!

Just got back from garage, on the FD there is some kind of electrical black connector thingy. 2 prong with 2 o rings that was leaking gas. So he is going to replace them and reinstall to see if that helps, gas is getting to the FD, I have spark, so maybe its that, maybe not. We will see tomorrow.

Sounds like the EHA...
 

I also had the same problem recently.

Yep that would be the EHA....

Would a leaking EHA be the cause of the car not starting? It seems unlikely, but who knows with these quirky cars.

My experience with a leaking EHA valve was a strong smell of gasoline from under the hood. The engine started and ran fine. Of course, the EHA valve was weeping gasoline ... the outside surface of the EHA valve was barely wet.

Well installed a new EHA, started for 2 seconds then died. He disconnected the EHA connector, same result. I also picked up a rebuilt FD, tomorrow hes going to install that and see if it works. Could the CPS be bad even if the car starts and runs for 2-5 seconds? He say that if the CPS was bad, it not start up like it does....strange runs fine for 3-5 seconds, then dies and no start, cranks over fine. ANYONE have ANY advice? I may just junk the car if he cant fixt it. Hurts me to do that as its been a great car over the last 5 years and 150K miles.

Fuel pump relay...?
 

behind the battery...

Fuel pump relay
 

Replaced today as part of the mas control unit.

Here in Florida we are forced to endure ethanol, such a deal.

Its the fuel pump relay. Looks like a black plastic case about size of a pack of king size cigarettes. It can be repaired if you can solder. Printed circuit breaks where contacts are soldered to the board. Box is located behind the battery covered by a plastic shield behind the firewall.