96 e300 won't start - PeachParts Mercedes-Benz Forum

charlie a. · #1 03-29-2012, 04:57 PM

my 96 e300 will not start. my wife parked it in the driveway and in the morning the car wouldn't start. the glow plug light went on and off and the the engine cranked but will not fire.
based on my past problems on this car i checked the glow plugs and one of them was bad so i changed it. tried starting it again but it just turns and wont start. changed the fuel filter - same results. the engine just cranked and cranked and puffed out black smoke but won't start at all.
checked for codes but computer says no code found. also tried to see if there are the tell tale signs of k40 failure-like green and red lights flashing from the rvm or weird ets/abs warning signs on the instrument panel but there are none. any ideas? clogged fuel lines maybe?

engatwork · #2 03-29-2012, 04:59 PM

I'm thinking fuel issue. Can you disconnect the injector lines at the injectors and see if you are getting any fuel out?

Jeremy5848 · #3 03-29-2012, 06:34 PM

Agreed, almost has to be fuel. The '96 is fly-by-wire: the IP has an electrical shut-off and if it isn't working the engine will get no fuel. The ignition switch and everything downhill from there could be the cause of the failure to start. Check ALL of the fuses, not just the ones under the hood. Check the K40 relay in the electrical box on the right (passenger) side of the engine compartment, about where the battery would be if it weren't under the rear seat.

Jeremy

GregMN · #4 03-29-2012, 06:59 PM

I had the same problem with my wife's 96 E300D.

It was a fuel problem. The O-ring between the fuel control unit and the IP was leaking. That allowed air into the fuel line.

I diagnosed it by installing a low pressure electric fuel pump in the fuel supply hose where the hose meets the hard line on the fire wall. Within a few seconds of powering on the pump, I could see the drip and find the leak.

$5 o-ring, 1 hour of my time, and it has not been a problem since.

charlie a. · #5 03-29-2012, 07:15 PM

are you referring to the o ring in the shut off valve?

GregMN · #6 03-29-2012, 10:43 PM

There is no "shut off" valve on that car. It is an electronic controlled (drive by wire) fuel flow control unit. There is an o-ring between the body of the fuel flow control unit and the IP. The o-ring is item #32 in the first diagram.

Your problem is most likely air in your fuel line. The air in my fuel line was due to the o-ring that I mentioned leaking air in. Your leak may be elsewhere. An easy way to find a leak is to gently pressurize your fuel source line and look for the leak. If there is a leak you will find it in a very short amount of time.

charlie a. · #7 03-30-2012, 12:00 AM

that's what i was referring to. i call it shut off valve. i've changed that o-ring a while back and it normally is wet underneath the sov when the o-ring is worn- but not the last time checked. i'll double check just the same. thanks

TMAllison · #8 03-30-2012, 12:08 PM

Follow the fuel path until you first see bubbles. Replace every o-ring prior to that point.

Is helpfull to park nose downhill and to have more than 1/2 tank of fuel when repriming.

fuelflow.JPG (image)

charlie a. · #9 03-30-2012, 04:01 PM

thanks terry- this diagram is very helpful
charlie

charlie a. · #10 04-02-2012, 07:32 PM

i still can't get my 96 e300 to start.
here's what i've done:
1. changed all fuel lines
2. changed fuel filter
3. changed sov o ring.
car will crank but not fire :
observation:
1.there is no fuel coming out of the fuel line to the prefilter from the thermostat after the fuel line change. tried to crank it while the fuel line is out of the prefilter but no fuel came out. bottom of the housing chamber is also dry-whereas it had fuel before i changed the lines and screen.
2. i can't see any fuel coming from the sov to the filter
3. observed only fuel coming from the i/p fuel pump to the filter -my guess is this must be old fuel from the i/p.
question:
1. can this be a bad fuel pump ? although-i hear it starting everytime i connect the batteries.
2. can this be a bad shut off valve-does the electromagnetic shut off mechanism every go bad? -based on past experience the only thing the goes bad here is the o-ring.
3.can this be related to the k40 relay? alldata says the fuel pump relay is in the k40.
any suggestion is welcome.

TMAllison · #11 04-03-2012, 12:44 PM

Open hood, open drivers window, turn key to pos #2. If you hear a good solid "click" when the key is turned thats your SOV opening. If you don't hear it, it will never start. SOV's do go bad; usually there is some warning like a delayed shut down when the key is turned off. K40's that feed it power can also be the problem although usually that also manifests itself while driving and the engine dies, as if the key were turned off. The valve is electro-magnetic, no power and it closes.

The fuel pump is a suction pump on the side of the IP. Mechanical, not electrial, so whatever you hear isn't the lift pump.......

Did you replace the big oring beneath the pre-filter? The one as big as a quarter up under the rim? Without it, it'll never prime.

If any line or oring is disconnected or open, it'll never prime. Has to be sealed to create suction.

The white clips on the fuel lines are "spreaders" used for removal. Properly installed, they are pulled back and are loose and floopy, not pushed tightly closed around the fuel lines.

charlie a. · #12 04-03-2012, 03:06 PM

thanks terry:
1. yes - i hear a click when i turn the key to position no.2. i even had someone turn it while i held the sov itself and both heard and felt the sov clicking.
2. if you are referring to the o ring that you have to buy separately from the prefilter-yes i changed it-unless there is still another o ring that is in there.
3.i've checked the fuel lines connection and made sure i hear the snap before locking the spreaders.
4. my question is -when you buy the fuel fiter-there are two o rings that come with it. but i was only able to find 1 slot in the tightening bolt where the bigger o ring goes in. the smaller o ring- i can't find a place where it goes in the bolt.
thanks again

Jeremy5848 · #13 04-03-2012, 08:25 PM

You have identified the right prefilter o-ring. The bolt for the secondary filter uses only one o-ring. i don't know what the small one is for either, maybe for some other use of the filter.

Baileyusa115 · #14 04-03-2012, 10:23 PM

This topic is out of my knowledge, but what about some kind of malfunctioning immobilizer? I'm not so sure that would be it, since it seems that he has a fuel problem, and I think that the immobilizer cuts out spark and not fuel...

Jeremy5848 · #15 04-04-2012, 12:44 AM

Quote:

Originally Posted by Baileyusa115

This topic is out of my knowledge, but what about some kind of malfunctioning immobilizer? I'm not so sure that would be it, since it seems that he has a fuel problem, and I think that the immobilizer cuts out spark and not fuel...

Spark? What's that???