I have a 1986 Mercedes 300e that will not start. It was ruuning fine all weekend and then Monday morning, it would crank, but never fire. It has always started with little effort and had no other symptoms up until then. I have checked the spark form the coil wire and the spark plug wires and both have a strong spark. I have checked the fuel pump relay. When I take the relay out, there is no fuel pump noise. After putting it back in and turning the key, I can hear the fuel pump turn on, but it turns off after 1-2 seconds. That leaves me with the fuel system which I do not have a manual for, but I did get the Bosch Fuel Injection Book to read up on it. From reading some other postings, it would seem that I need to look at the fuel pressure accumulator, fuel pump check valve, fuel pressure regulator, cold start valve, and the EHA. Also, I should replace the fuel filter because it might be clogged. I do not know which to check first. Is there an order in which I should go about this and have I overlooked anything?

Thanks,
Mike

PS - I have looked all over the net for info and this site is by far the best one out there.

Most of the time, if the fuel pump is working while cranking, the coil will be faulty or the rotor button stand has broken under the distributor cap. The coil can be putting out spark under no load, but when in the cyl and under pressure, the plugs will offer more resistance. This can cause the coil to show up faulty.

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Benzmac:
1981 280GE SWB
1987 16V
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

Benzmac, did MB use the EZL ignition system on 1986 300e's? If so, doesn't the ECU shut down fuel if the spark is faulty or not on spec. I seem to remember reading or hearing about that happening, or maybe it's the other way around. Anyway, Marzilli, try this, it may get you headed in the right direction. If you are getting fuel, but no spark, go to the rear of your car (or get a volunteer) and sample the aroma coming from the exhaust whilst cranking the engine. If you (or your volunteer) smell raw fuel, then you most likely got spark problems.. If not, then most likely fuel problems. Have a great day!!!!!

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Jeff L
1987 300e
1989 300e
1987 BMW 325

I was having the same problem with my 1990 300E, perhaps less severe. Luckily I had the visual indicator of fuel dripping in the area of the fuel pump, and I replaced the pump, washers, and the line that leads into the pump from the tank. Since a buddy of mine runs a shop I got the parts at cost, and since then I've had no starting problems whatsoever....in fact I'll be adding an automatic starter to my alarm system tomorrow or sometime this week

hope this helps...

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Chris Singh
1983 300D 200k+ (stopped odometer)
1990 300E 123k
1999 E430 12k

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