On my 1994 Mercedes E320 wagon, the start igntion will turn over and cranking but will not start or fire up even though the engine was running good a week ago. What am I missing here?

I had this problem before. At that time about 4 years ago, I replaced fuel filter and the two fuel pump motors. I have not driven the mercedes much at all. This time I replaced the battery with a new one and the ABS/asr motor pump was replaced as well.

There are so many articles about the issue of crank no start. I came up with a list like a troubleshooting tree not necessary in order. Hopefully through a process of elimination will determine the problem narrow down to a specific location and/or possibly parts replacement.

1. Check the fuel lines to see if the fuel/gas is coming through. Where is the end of the fuel line on top of the engine so I can disconnect the fuel line and turn on the ignition to see if the fuel is coming through the end of the fuel line?

2. Check the fuel pump relay located behind the battery located on the right side passenger, usually is a green relay with 30 amp fuse. The 30 amp fuse is good not broken, etc.

3. Check the fuel injectors to determine if fuel is coming through and can that be done? I replaced both fuel injectors pack along with the spark plugs awhile back and should be ok. Check to make sure the spark plugs is in good working condition. Might have to replace fuel injectors and/or spark plugs again.

4. Check the MAF sensor located on the top of the engine clean out with MAF spray. I already did that. There was a kick or trying to start/turn over after I sprayed the MAF sensor for a second or two. How to to make sure if the MAF is working properly or not?

5. Check the spark plug wires and should be good since I already replaced them with new ones a few years back as well.

6. The carbureator or distributorless was repaired and rebuilt and I don't think that is the problem.

What other areas need to be check out not mentioned above? Anyone out there have any ideas, comments, feedback/advice is greatly appreciated.

Update: I read somewhere that a bad/defective OVP relay can cause the turn over crank no start issues.

I tried 2 other ovp relays I have that are supposedly good. However, the same thing happen, crank turned over no start. Also, I noticed when I tried to use the self testing 16 pin dm (diagmostic module) when I turned on the ignition light on the dashboard only not to start, it only shows red and not blinking at all and not giving any codes. I wonder if it is related to the OVP malfunctioning? The same thing happen to all of the three ovp relays I have.

In addition, I did some little research on the OVP manufacturers. Here is the list below I found so far:

KAE Kaehler Overload Protection Relay (OVP)

MB Overload Protection Relay (OVP)Genuine OEM Overload Protection Relay for Mercedes 0005406745

Uro ovp

GEBE ovp

V30 71 0027 Vemo Overload Protection Relay P/N:V30 71 0027

MEYLE Abs Overvoltage Protection Relay For MERCEDES S202 W202 92-00 0005405245

WEYKOS 0005406745

Daisy Auto 0005406745

I wonder why only the recommended OVP relays are the Mercedes and the KAE Kaehler brands? Is it because of the other brands as mentioned above do not last long and are prone to earlier/shorter breakdown failures?

I also wonder if the ovp relay failure can cause abs/asr lights on the dashboard to come on and not the fault of the abs/asr motor pump itself and/or the abs/asr control module as well? Does the braking issues is caused by OVP relay failure? What about 16 pin Diagnostic Module (DM) not to work properly due to OVP failure?

Comments, advice, feedback is greatly appreciated.

First narrow the diagnostic to which is causing the problem i.e., spark OR fuel. Let's assume compression is good. With the key on check to see if the fuel pumps run, you should be able to feel them run by touching them. If they run check the Schrader valve for fuel pressure at the beginning of the fuel rail...this is an M104 twin cam engine correct?

Good luck!!!

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"Rudeness is a weak man's imitation of strength" - Eric Hoffer

Hi Sugar Bear, thanks for the post. Will follow up on your advice. Stay tune.

I am not sure what you mean by M104 twin cam engine?

Is your wagon a 4Matic?

__________________
"Rudeness is a weak man's imitation of strength" - Eric Hoffer

yes I believed so it is 4matic.

Does it say 4Matic on the tailgate? Where is the air cleaner driver's side big and round or passenger side behind the headlight?

__________________
"Rudeness is a weak man's imitation of strength" - Eric Hoffer

Sugar Bear, there is no 4Matic on the tailgate and the Air Cleaner is on the passenger side behind the headlight and it is box type not round.

I did use the starting fluid spraying in the intake manifold and sure enough it start to run for a few seconds. The same thing happened MAF sensor located on the top of the engine clean out with MAF spray as I mentioned earlier in this thread.

In addiiton, I noticed the tab broke on the side of the intake manifold. It is a sensor type thing and I am not sure what it is. Although the tab broke, the sensor fits tight and working. See the pictures below>

Attached Thumbnails

     

That's an M104 engine, that's good. See if the fuel pumps run.

__________________
"Rudeness is a weak man's imitation of strength" - Eric Hoffer

Yes, it is m104 engine. How to check and feel the fuel pump vibrations/movement without going under the car to remove the guard and see the fuel pump and feel it at the same time turning on the igntion to get the fuel pump feel?

Need two people or alternatively attach a fuel pressure gauge to the schrader valve port on the fuel injector rail. Remove the black plastic cover on the left side of the valve cover to expose the fuel rail, the valve is above the 3rd injector.

Should have about 35PSI, if not first thing i'd check is the fuel pump relay, IIRC the relay is behind the battery near the OVP. Also check all fuses, read the fuse cover to see if any say fuel pump.

Good luck!!!

__________________
"Rudeness is a weak man's imitation of strength" - Eric Hoffer

Sugar Bear, thanks for the last post. Will a regular tire inflator guage work on the schrader valve port on the fuel injector rail? If not, I will go to auto parts store for a loaner tool.

I just watched the video on the fuel pressure guage. Never mind the tire inflator guage, it won't work, sorry!