Just purchased a beautiful 1987 300E! Just love the car! But- hopefully someone can point me in the right direction- it has 181,000 miles,automatic,and completely rust free. My problem is that in the morning when its cold-It cranks and cranks and cranks -to no avail-then after pumping the gas pedal numerous times,it will turn over and "catch" at an extremely low idle-if I try to give it more gas it dies- then we start the process of pumping the gas pedal again,till it starts again-rough at best.But,after it does start-it will run fantastic- .The other thing I have found is that at a red light or stop sign-it seems very slow off the start,but then when it shifts its like some one hit a turbo button.
Any help would be greatly appreciated! Please - I just love this car- but in the morning its most frustrating.Would love to fix this problem- thought at first it was a dirty carb-but doesn't seem to be

 

Sounds like you may have a couple of things going on. For the hard start in the morning- You are losing fuel pressure somewhre. It could be the fuel pump check valve or injectors leaking down, also check for any external leaks. You will need a fuel pressure tester to know for sure. If you don't have one, the check valves are pretty cheap. Just be sure to change all the seal rings you disturb. Next it sounds like you have a vacuum leak somewhere. If you have access to a smoke machine to test it that will be the fastest way to find it. If you dont then a couple of cans of carb cleaner will work. With the engine running, slowly spray a little at a time around the injector seals, intake gasket, and especially the idle air valve. The rubber hoses going to it are bad about splitting. One other thing I have seen is the plate on the air mass sensor comes out of adjustment and sticks in its housing. If it needs adjustment just cut four strips of paper about an inch wide and use them to space the plate evenly in its housing as you tighten the center screw. do this with the engine OFF. Anyway, that's a short list to get you started. Of course check all the basics like the distributor cap and plugs, etc.

 

I have a simular problem with my 92 300e with 188k miles. It takes about 7 attemps before my car starts. The problem seems to be worst when the tempeture is colder. Once the car start, ir runs like a Dream. Did any of the fixes Work??????

 

Hi guys,

I've got the same problem with my 1989 260e. There's a humming noise coming from what I believe is the Electric Fuel Pump. My Car has 209,000 Kilometers, 130,000 Miles. Even though I am not a mechanic but mechanically inclined I tried to check the Spark plugs to possibly change, but I can't remove the leads from the plugs, is there a trick to it or are they stubborn. Your help would be most appreciated.

Thank you,

Chris....From the Land of OZ.

 

Get a spark plug boot puller. Mercedes has one that is pretty cheap. It's like a pair of pliers, with the ends made to grasp the metal boot on the end of the wire. They are worth getting just to save the wire ends.An e-bay search should turn something up also. Just make sure you get a set made for the 103 engine.

 

I have a similar problem with a 1990 300E It looses spark if you push down hard on the gas and sometimes has no spark when the engine is hot. It will usually start right up cold and drive ok if you take it easy. I put a spark tester on the coil wire and so long as you accelerate slowly the spark is a bright blue, if you hit it hard it breaks up and turns yellow. Bad Ignition module or crankshaft sensor? thank for any help