'88 300E Power Loss
 

Lately my 300E has been difficult to start after warming up and then running into a store and coming back out to start the car. But after five to ten minutes, the car starts right up. This morning while cruising down the road, I lost all acceleration, the car stalled and coasted to a stop. It would not start back for about 5 minutes. I am thinking this is a fuel pump problem; any thoughts or suggestions?

It sounds more like a bad OVP to me. As if solder defects had developed so that it drives the EHA intermittently -- leaving you in limp-home mode sometimes. Even in limp-home mode, the car should run well, so I would also suspect other problems in the fuel system such as bad mixture adjustment, vacuum leaks, injector leaks, etc. You can diagnose these things with the manuals on CD, a multimeter, and a vacuum tester.

However, my experience with this problem has been that it will save you money in the end to take it to an experienced MB tech that can isolate the exact problem, rather than throwing parts at it.

Hope this helps! Cheers,

sounds like you'll be getting your hands dirty this weekend!
you may have two or more problems here.
old tired fuel pumps like to stop when they are hot.
fuel pump relays on the other hand will shut you down any-time!
if the pump is loud or howling it's junk!
you can throw your o.v.p. in the trunk and it won't shut you down it will only run like poop!
AS FAR AS LIMP HOME MODE. 88 300E HAD NO SUCH THING.
MF

Mike,
Thank you for the clarification. Maybe replace the fuel filter and accumulator if you change the pump? Cheers, Andrew Seidel.

reference:
http://www.peachparts.com/shopforum/tech-help/6670-300e-cuts-out.html?highlight=300e+limp

ESM,
I see that you had the same (or similar) stalling problem back in early August.... did you ever resolve this? If so, did you replace the OVP?
If not, I suggest the OVP is still your primary problem.
Good luck! :o

After crawling around under the car for several hours and not having the necessary testing equipment, I broke down and paid a visit to a new independent mechanic. I stayed with the mechanic while they ran the usual diagnostic tests (checked for spark, fuel...). I explained to him that I replaced the OVP in August and that the plugs and wires are less than a month old. He suspected the fuel pumps but was not convinced. After another 20 minutes of looking around, he got the car to shut down on its own and tested the fuel relay. BINGO! The fuel/MIL relay was the culprit. The car has been running fine since. Although while standing by during all the testing, I could hear the bearing in the water pump, so it looks like I have some work to do in the near future.

If anyone is looking for an independent Benz/BMW mechanic in the Detroit Suburbs, A-1 Automotive in Rochester. Excellent group, clean facility and only $62.00/hr labor. The dealer in town is currently $99.

esm,
Thanks for the update! I'll take a closer look at the fuel relay next time my CIS-E cars act up. Cheers, Andrew Seidel.