Hi, guys...

My fuel pump died on me last week, so I picked up a new one, complete with the driver side sending unit and brand new relays (cheap insurance). Installed everything, and noticed right away something along the way of fuel delivery wasn't quite right...

The car started and ran perfectly in low to mid throttle but under hard acceleration bogged badly. After one or two full throttle attempts, the fuse to the pump blew. I put in a new fuse, turned they key, and that too within seconds blew...

I felt the wires going to the pump and noticed they were warm. I pulled the harness off the pump, put in yet another new fuse and turned to key on (with the harness disconnected) to see if there was a problem in the line / harness. No problems. Fuse was fine, leaving me to believe the harness isn't grounded or shorting out somewhere (as I have read has happen to others). I plugged the harness back on to the pump, turned the key on again, and BOOM... fuse blows right out!

So this leaves me with just one thing... The brand new fuel pump? I've seen brand parts be defective before, but has anyone else experienced this? What are the chances the fuel pump was defective to begin with? It was a brand new, sealed unit from MB. Not aftermarket, not reman, or anything like that. I'm going to assume it also has a warranty, considering it's not even a few days old. Anyone know what the parts warranty is on OEM items such as a fuel pump assembly?

Could there be any other problem that may be suspect to cause such a condition, or is it just a bad "new" fuel pump? What about the injectors? Could they function (or lack of) cause the pump to over draw itself? I haven't had a chance to check fuel pressure, since the pump wasn't really operating correctly.

As a note, this is on my 2006 CLS55 with 70K miles...

Any input, ideas or suggestions would greatly be appreciated!

 

Well... In case anyone was wondering... It seems MB gave me the WRONG sending unit and fuel pumps!!!

They were NOT for the 55 motor!!!

Waiting for the new units. Will post the results as soon as I get them in and running...

 

Problem solved!!!

Parts counter made the mistake, so they made good on the transaction and I got the right sending unit and pump assembly...

So I guess the only thing I can leave here for all you guys... DOUBLE, TRIPLE CHECK the items you purchase to make sure they're the right parts for your application before you leave the parts counter!