My 88 300CE died last week. It was aidling a little rough but one day it just died at a stop sign. After that it wouldn't start again. When I try to start it runs for 1-2 sec and then dies. I beleive it is my fuel pumps. I would like to hear your opinions on this problem. And if somebady could tell me the locations of both fuel pumps for a 88 300CE I would appreciate it.

Make sure it actually IS the fuel pump before spending money.

The first check should be electrics (have you got a spark?), then fuel pressure (Tee-into the fuel pipe).

These can both be done easily and cheaply, and could save you a fortune at the dealer.

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Paul Gibbons
'93 320CE
'73 Jensen Interceptor (Resting)
Giant Full Sus Mountain Bike

I believe the fuel pumps are under the car and the stall and not run problem could be your fuel relay.

This is the diagnostic method I would try:
1.- Turn the key to the on position (do not crank) and listen for the fuel pump. If unsure of what you hear, walk around the car to where the pump is located. (Mine is somewhere behind the passenger's side rear wheel).
2.- If you hear the Hummmm, chances are the pump and relay are good, look for a spark problem.
3.- If no Hummmm, take the fuel pump relay out, jump the terminals, and place the relay back on the socket. (for this you will have to do a search, since I do not know the terminals from the top of my head, relay is located somewhere behind the battery in my car))
4.-If pump now Hummms, you know the relay is the problem, if no Hummm, the pump has a problem
5.- Try that first, and then we go for the spark problem (if any)

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1999 Porsche 996 Carrera Convertible
1994 420E - SOLD
1986 300E - SOLD, what a car
609 Certified

I can hear a hummm from the pumps so does this mean its is an electrical problem or could possibly be that one of the pumps is bad and one is good. Thanx for your help.

Check the ignition coil. It could be faulty.

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Zorin

'88 Benz 420 SEL
'79 Porsche 911SC ('87 Carrera Engine)
'00 BMW 540 Sports Package
'99 Land Rover Discovery

86 300E - Manual (sold)
88 260E (sold)
84 944 (sold)

The Humming is there. But you have 2 pumps?
Ok, do the following:
Turn the key on (do not crank), and place your hand on each pump. Obviously at least one of the 2 must have some vibration. Then the other pump must be bad. Althought I am not sure whether both pumps should come on at the same time for startup.
Zorin has a good suggestion, the ignition coil could be faulty (no spark).
Preferably do this in some degree of darkness:
Take the wire off the center socket in the distributor (from the coil), and place it close to ground (anywhere on the chassis). Crank the engine, a bright spark should be visible jumping from the wire to the chassis.
If no spark, either cable or coil might be bad.
If bright spark, possibly the rotor or distributor cap is bad.

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1999 Porsche 996 Carrera Convertible
1994 420E - SOLD
1986 300E - SOLD, what a car
609 Certified

1991 300TE ran great but would occasionaly "die" at idle, like coasting up to stop sign. One day it just died and wouldn't start. The distributor was cracked ... has not happened again since replacement. I'm sure though that there are many causes for this symptom.

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1992 Black 500e
1991 Black 300te 4m
1992 Black Renntech 620sl
1979 Porsche 911sc targa

"Turn the key on (do not crank), and place your hand on each pump."

The catch here is that the pump(s) will only run for a couple of seconds. This means someone else would need to turn the key.

Or, you could jump pin sockets 7 and 8 at the relay. This would make them run continuously.

Or, you could run a pair of long jumper wires from the battery to each pump and test them individually.

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1986 300E 5-Speed 240k mi.

So how can you tell if the ignitoin coil is bad. Also which one would I order the
A-511983
or
A-511984
I will run the tests you tell me to do.

Those 'chassis' numbers are related to your VIN.

For example, my VIN is WDBEA30046A193

The numbers following the first "A" are what you want to match against. One part is listed for chassis numbers <= 511983 and the other is for >=511984

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1986 300E 5-Speed 240k mi.

Let me share my experience with you. This happen to me back in May 2003, just like the problem you have right now. My 88 300E died on a stop sign also. Some Mercedes shop will tow your car for free. I took my car into a Mercedes shop to save me money. Why did I say say save me money is because trouble shooting is better than guessing. Anyway the problem is the voltage regulator on my alternator. It drainned out my battery so it won't even crank my engine.