Very Bad Running 300E
 

Hey guys I have been through the site a lot in the past week looking for what could be wrong with this car.

I have a 1988 300E with 167k. Car was given to me by father in law. It ran great and had MB service the entire time he owned the car. Now on to the good stuff.

Wife had been driving it and said that the blower wasn't working anymore. No issue for me as the car is still cold when I arrive at work 3 min drive. I took the car from her filled it with 87....I know. Anyways the car started to drive really bad. It felt like it had a bad miss. So I pulled the plugs and changed them. while I was changing them I looked at the rotor and cap. Did not look good but thought is this fixes it then I will change that a little later. Again got to #5 broke the wire. Went and got new wires. Replaced all of them and it was still running bad. Then on the way home i looked down and remembered oh **** it needs premium fuel. So i went and bought some lucas oil octane booster and filled it up. No change. Drove it a few more days with the bad miss but fine idle. Then it got worse so I replaced the rotor and cap. No change. Tested the coil. Got a MSD coil to replace it with but have not changed it since I do not believe that is the problem. This weekend I seen that it was at a half tank so I filled it back up with 93 octane. Ran great after the fill up. Went to drive it in the morning and it was running ****y again. Just drove it to the store to get cigs and it is really running badly. It will not idle or drive unless I FLOOR it. You can shut the engine off then start it again and it will idle for about 15 secs fine then starts to pitter and putter. Floor it it will idle again in the same sequence. ANY IDEAS........ I am quite familiar with cars besides mercedes. I have owned many race cars but am at my self with this one. PLEASE HELP.

I am thinking that maybe the fuel pumps but am really unsure. Car has always been driven never sat around

You should have let the tank empty out before adding the fresh gas, epecially if you aren't buying quality gas (toptiergas.com).

My MB had about 8 gallons of 'bad' gas in it (from sitting) which I put in my '00 Sierra. Truck ran like crap, hard start, stumble, etc... basically the driveability you're describing and only got slightly better when I added 10 gallons of premium (only requires 87).

This time I ran the tank almost dry before refilling, and full tank of 87 had it back to normal.

Still, it wouldn't be a bad idea to check and see if your pumps are running, how they sound & what kind of current they're drawing.

If you haven't changed the fuel filter(s) lately, that might be something else to look at.

I only use sunoco and BP. I just can not imagine that this gas would be causing this problem with the octane booster and the 10 gallons of 93 octane. How can I check these fuel pumps. I here there are two? Where are the filters located.........Any other ideas?

I am unfamiliar with Mercedes engineering so if you offer advise can you please offer guidance with it. Thanks

300E
 

Check the DIY links for info on the pumps and filter. It is easy to change the filter. It might be clogged or contaminated.........................

I dont see anything that describes the location of the filters in a 300e. Lots of information on the diesels though

Fuel filter and fuel pump is inboard and in front of the right rear tire/wheel ... accessible from underneath the car. There should be a black plastic cover over the fuel pump and filter to protect them from road grime. Three 10mm plastic nuts hold the cover in place.

I had this exact same problem with my 560SEC. Turned out that the fuel filter had become clogged, and was causing fuel pressure to drop drastically. Changed the fuel filter, and it ran great!

Shortly after that, my fuel pumps both died, my mechanic said it was because of the strain that the clogged fuel filter had put on them. So they worked for a while after that, but they sounded really bad, and were on their way out.

Fuel Pump
 

My 1989 300E had difficulty starting up hot or cold. It would start and die or would take several attempts to get it going. I had to change the rubber fuel line from the fuel filter to the metal line due to a leak earlier this year. I changed the fuel filter since I was down there too. After changing the filter, the old gal fired up right away, hot or cold without hesistation about 95%+ to this day. The old filter must have been clogged or contaminated...........

As suggested above do replace the fuel filter and the adjacent fuel accumulator .
Next would be to clean the tank filter/ strainer. with this end clean most fuel starvation and hot starts (accumulator caused ) will be sorted.
mak

Thanks All. This sounds much easier to change out then my 04 cobra. Gotta drop the entire IRS Subframe to get to it...I will try this and report back tomorrow night

where can I find the accumulator at????

Here :)

To purchase

This website would be a good place to purchase new parts.