Help Diagnosing an Odd Problem - Broke Down Again, Need Help! - PeachParts Mercedes-Benz Forum

Squabble · #1 04-19-2011, 12:27 PM

yesterday my 1978 280CE m110 stopped running as i was driving down the road. literally just died out from under me. some of the cluster lights came on, lost all power and gas pedal response. would crank fine but not turn over. lights all worked, stereo still worked.

sat in the road in the cold rain with the police behind me for 20 minutes waiting for the tow truck. took about half an hour to get towed home and bill paid. another twenty minutes pass in the cold before i can get back out and take a look at her. sit down and she starts right up! left her idling for awhile, revving here and there, and there were no problems. turned on AC & heat to make sure there were no vacuum issues. lights and electrics all worked fine.

recently had the fuel filter replaced and let the gas get close to empty to make my indy's job a little easier. also had a brand new e-brake cable installed, if that means anything... maybe bumped into something related?

my first guess is the fuel pump. it's old to begin with, maybe got some stuff stuck in it when the filter was changed, or maybe stuff got picked up off the fuel tank floor when i let it run low. just came out of storage two weeks ago or so. anyone know how to test fuel pump issues? what about the relay, do i have one? i thought i heard somewhere that a fuel pump will shut down when it warms up or heats up if there's a problem and then would run fine again when cold.

only other issue that i haven't tackled yet is a sluggish "bogging" out that happens when you put the car in drive and take off from a stop. smooths out very quickly after that, not an issue when idling, but feels like it might want to stall out when i first take off. scheduled new injectors with my indy in a couple weeks and thought that might take care of it.

any ideas? thinking about running some injector/fuel system cleaner through the fuel tank, maybe putting in some Heet water remover? sound like anything else to anyone? this is my daily driver and i'm grounded for awhile bumming rides, because of this, and this: http://www.peachparts.com/shopforum/showthread.php?t=297592

thanks for the help!!!

edit: i know this isn't the ignition control module, ignition coil, or pick up assembly, or spark plugs, as i replaced them last year. similar symptoms to the dead ICM so i thought i'd throw that out there.

JohnM. · #2 04-19-2011, 03:04 PM

Your 280CE has a fuel pump relay just like all the other Benz's of the era. I would check it. IIRC its in the driver side of the engine bay somewhere.

Squabble · #3 04-19-2011, 07:40 PM

well, i opened up the box with all the relays under the hood and found this. take a look at the attached pix. the red wire is unplugged and possibly broken. anyone know what this does? can this be related?

also, starting to get concerned that i bought a fuel filter that doesn't match with my VIN number, as in i got a later version vs. my early version. could that be related? restrict flow after a few miles of driving? maybe make the pump work too hard? what do you think?

JohnM. · #4 04-19-2011, 08:33 PM

None of those are your FPR.

The FPR sits by itself somewhere in the engine bay, not with the other relays. It is a black plastic cube with 6 pins IIRC.

Squabble · #5 04-19-2011, 08:47 PM

looked all over in the dark with a flashlight and can't spot it. will have to wait until tomorrow...

JohnM. · #6 04-19-2011, 08:49 PM

Sorry I can't give you an exact location. Its been awhile since I've worked on one. But I do remember it being in an odd location. It might have a cover over it.

Squabble · #7 04-19-2011, 09:01 PM

yeah, that's what i thought when i popped off the cover of the other relays, must be in there.

i just took a look at the diagram in my performance benz catalog of the relays and it doesn't list a fuel pump relay for 1978. it actually only lists them for 1980 and newer w123 gassers. think it's a mistake? do they just not list/carry that relay?

even Fastlane lists fuel pump relays for cars with a later VIN number than mine...

JohnM. · #8 04-19-2011, 09:42 PM

Ok. So upon more research, I lied. The FPR should be the inner most relay (closest to firewall) in that cluster of relays you pictured. The later ones must be different.

Squabble · #9 04-19-2011, 09:51 PM

excellent, thanks! is this what they call an "ice cube" relay? anyone know if this is a six pin or five pin? will any five/six pin relay work in it's place? i can't seem to find one listed except for the large black later model relays.

guess i can just go pull it....

do they just pull straight up to come out?

JohnM. · #10 04-19-2011, 10:17 PM

Should be a 5 pin. Not sure on interchangeability. Should pull straight up yes.

Cal Learner · #11 04-20-2011, 08:45 AM

Squabble, wouldn't finding a wiring diagram for that chassis be useful for you? Like, for instance, figuring out what the disconnected red wire is for? Just a thought.

Squabble · #12 04-20-2011, 09:01 AM

yes, most definitely. as a newbie shade tree mechanic i've looked at wiring diagrams and my eyes crossed and fell out of my head trying to understand what i'm looking at. guess i should grab one and just hit the books.

however, with the wire attached and with the wire disconnected, the car starts right up and drives...

i'm thinking the symptoms coinciding with warming up and cooling down still point towards the pump itself. but again, i'm just the shade tree who cut his teeth on the OM617...

Quote:

Originally Posted by Cal Learner

Squabble, wouldn't finding a wiring diagram for that chassis be useful for you? Like, for instance, figuring out what the disconnected red wire is for? Just a thought.

PATLESS · #13 04-21-2011, 08:04 AM

I have a 1985 euro 280CE that does the same thing a couple times a year. Mostly during the cold winter months. It only happened twice this winter. When it first happened, Phil thought it to be the fuel relay, had to order from Germany,(very expensive). It seems to just die, but I have beeen very lucky, it has always started right back up, before I even stop. Would love to find the cause. Keep us updated.