Mercedes-Benz Forum banner

1 - 11 of 11 Posts

·
Registered
Joined
·
156 Posts
Discussion Starter #1
I just recently bought a 1988 300E 3.0 L6 Automatic. It has been starting and running fine for the past month since I have had it but all of a sudden it has ceased to start anymore.

The last thing that happened before it quit I was comming home from a friends house with an 1/8 of a tank of gas. At first the following day when it wouldn''t start I assumed it was due to either low fuel or maybe water in the line. So needless to say I put 5 gal of premium gas in it and tried starting after priming the fuel system with the key (turn to on for 10 secs to let fuel pump prime line, repeated several times). It kicked over for 2 seconds then shut off. I tried again and it ran for 10 more secs and quit. Nothing after that.

It seems if I let it set over night, or for a couple hours at least, and try to start it again it will fire for a good 5 secs and quit. Then not start.

Starter is spinning normal, no codes on the computer, half of a tank of fuel.

someone please help!!

Thanks a bunch
chris
 

·
Registered
Joined
·
156 Posts
Discussion Starter #4
so all youve done is add premium fuel.

no spark plugs, rotor, cap, wires, tune up, new filters, etc?
whats the history on this car.
When I purchased the car it came with the past 4 years of service reciepts. According to those within the past year it has had all necessary tune up parts changed. Also for some reason the Injectors and the fuel distributor block was replaced by a mercedes dealership. That was about a year and a half ago. I inspected the car over really good and it seems nothing is missing, and everything is hooked up correctly. It was taken very very good care of overall. Even the engine bay had been cleaned on a regular basis it seems.

I recently noticed that when I make the attempt to start it after a number of rotations I can smell fuel as if it's flooding. There is spark, and plenty of air, and being that I am smelling gas I assume im getting enough fuel. Hell maybe even too much. Every time I open the hood I find more and more locations for fuses and relays. Where exactly is the fuel pump relay?
 

·
Registered
Joined
·
2,227 Posts
There should be a plastic wall behind the battery. Behind the plastic wall is the fuel pump relay. Its a rectangular black box with 6Zyl written on it.
I would also check the OVP relay ( the relay with the fuse on top) next to the fuel pump relay.
When the car dies and you turn the key roll down your right back seat passenger window and see if you hear the fuel pump(s) engaging with a buzzing sound coming from in front of the rear right tire?
 

·
Registered
Joined
·
4,649 Posts
If you have fuel and have spark, the car should have started. Based on this, your fuel pump sounds like its working and your normal "tune-up" parts are serviceable enough to get the car started. Based on what you are saying, (fuel and spark are okay, and the car was running well), vaccum leaks would be something to look for but not normally something that would fail overnight. My original thought was the fuel filter is clogged but you say you have fuel.

Are the plugs wet after you try to start the car?
 

·
Registered
Joined
·
72 Posts
From your symptoms, my money would be on the fuel pump relay. My '86 did the same thing this past summer, and the fact that it starts but then quits after sitting is exactly how mine acted. The relay is not cheap however...if I remember correctly it was a little over $200.
 

·
Registered
Joined
·
7 Posts
First thing I would do is check the fuses on the OVP relay which would be the most common problem, I would also check to see if it had ever been replaced, If not replace it. The next thing to check would be the Crankshaft position sensor that goes to the EZL or ignition control module. The original sensor gave a lot of problems I would check to see if it had ever been replaced. This sensor can be bad and still give you random spark occasionally. Don't do what I did and just start replacing everything in sight.
Your symptoms really would direct me to the CPS, although I guess everyone here is just guessing and its very difficult to give you an exact answer.
Good Luck, Anton
 

·
Registered
Joined
·
156 Posts
Discussion Starter #9
First of all thank you everyone for your help up to this point!!!

well when it finally warmed up outside I pulled all relays I could find to check the connections, and it seems some where dirty. After cleaning all dirty connections I could find and re seating everthing it fired up!! ran really rough for the first few minutes and then leveled off again. I dont know if it was a fluke, just dirt in the way, or its just in remission for the time being. Next stage is that fuel filter and the OVP (whatever that means).

A lot of signs are pointing towards this car sitting at one point for a good while. Considering the millage i would bet my money that someone had this thing sitting out back while they had another car as an everyday driver. hopefully its just a combination of a lot of little issues making it seem like something major.

And long before i pay 200 for a relay ill rewire it with something else like i did the ignition lock cylinder. That stupid thing failed and it would have cost me more to get it fixed with mercedes parts than i paid for the car. Needless to say a one universal cylinder and ignition switch later and it turns over fine. An early 80's Datsun Nissan truck cylinder would have been better however for anyone having that issue in the future.
 

·
Registered
Joined
·
49 Posts
91 300e no fuel to injectors have fuel to distrabution could it be something in the fuel distributor?
You can jump the Fuel Pump Relay by connecting plug #30 and the one right across from it (labelled on the underside), connect the battery (will hear the pump run) and if you press the Air Flow Meter plate down with an injector line disconnected from the top of the distributor you should have fuel flowing out the top. My issue is that there is no fuel flowing when I press it. :(
 
1 - 11 of 11 Posts
Top