Hi fellow enthusiasts;

I am new to this site so be kind. Here goes.

I have a 72 280se 4.5 that keeps stalling. It cranks over but won't restart. First time into the shop they tracked the problem to the EFI ECU ($$$ ouch!!) They replaced it and it quit the first day I got it back. Second time into the shop the car started when they went to try a diagnosis, so they played with the points and condenser. It took about 2 weeks the next time to quit and again started up after it was towed to the shop. They cleaned all the relays and conections having to do with fuel supply. The car is now in storage during the winter months and I am now leary about venturing off any distance from home.

A couple things that might help.
Cold or hot--doesn't matter
Can't here the fuel pump when key is turned on.

I think fuel pump. What do you think?
Any suggestions would be appreciated.

Jeff

Stops Running
 

Definately sounds like the fuel pump. I had a very similar problem with my 4.5 a few years ago. Had the pump tested by my local MB mechanic and it was truly the pump. Phoned Europarts and had the problem solved in a couple of days.

In my very humble opinion, when the ECU fails I think it tends to be catostrophic. The ECU is a big ticket item on that car and I find reprehensible that the mechanics would use replacement as a diagnostic tool. I don't mean to trash mechanics, as the majority are very ethical, but it's the small minority that makes it difficult for the rest.

I would find someone (Dealer etc) with the appropriate Bosch Tester and have a proper diagnosis performed on the vehicle. Within minutes of plugging the tester into the ECU the mechanic will be able to tell if it's the pump or not.

Good Luck


Chris M
71 250CE

Can you handle a wrench or two on your own under the hood?
If so, you can pinpoint diagnose the whole system with 3 basic tools...

1. A multimeter.
2. A fuel pressure guage that can accurately read 20-40 psi.
3. a fuel line clamp (pep boys for about 8$).

If you haven't got the 108-109-111-113 manual I strongly suggest you get one (try the parts shop first, then try 1-800-for-merc, lastly try ebay).

Send me an email and I'll reply with a zipped file that has all the relevant manual pages on the system from several sources.

-CTH

PS. It doesn't hurt to have the box that Chris mentioned, he should know, he has mine. :) But a mulitmeter and some patience can do the job. BTW, a working ECU just sold on ebay yesterday for 50$. A non-working one for 14$.