Is it the fuel distributor?

[austinite]

CAR: 1987 300e w124 (automatic)
PROBLEM: Starter cranks, but engine won't start.


The lastest theory is that it's the fuel distributor, but that's a big investment, to not be sure. Searching as much as possible, other terminology has popped up:

Vacuum leaks, O2 sensor problems, EHA current, Throttle Position Sensor, cap rotor, injectors, and MAF, and even a corroded radio interference resistor in or around the distributor cap.

Would any of them lead to such a complete and abrupt failure?
Are there any affordable tests to eliminate these others as the culprits?



I've done all the affordable stuff I know of:

Replaced sparkplugs
Checked Spark
Compression test
Starter fluid test
Sound check for fuel pump (Thanks Don!)

Results:
---------
Spark check: My friend held one of the sparkplugs to the block and got a good shock: good spark but bad boot, but would this stop the car from running?

Compression test: good, range 159psi - 178psi

Starter fluid: Had someone spray starter fluid, while I started the car. Engine ran as long as both the fluid was being sprayed and the accelerator pedal was being pushed down.

Heard the 1 second buzz that signifies the fuel pump is working.
--------

If it means anything, the car stopped working without any previous symptoms and it was when I tried starting it, not while driving. I also thought I heard a small single thud coming from under the hood at the moment the problem started.

Thanks for any help,
david

PS: What is the small red wire that attaches to the battery?

[GeorgeMurphy]

CAR: 1987 300e w124 (automatic)
PROBLEM: Starter cranks, but engine won't start.


The lastest theory is that it's the fuel distributor, but that's a big investment, to not be sure. Searching as much as possible, other terminology has popped up:

Vacuum leaks, O2 sensor problems, EHA current, Throttle Position Sensor, cap rotor, injectors, and MAF, and even a corroded radio interference resistor in or around the distributor cap.

Would any of them lead to such a complete and abrupt failure?
Are there any affordable tests to eliminate these others as the culprits?



I've done all the affordable stuff I know of:

Replaced sparkplugs
Checked Spark
Compression test
Starter fluid test
Sound check for fuel pump (Thanks Don!)

Results:
---------
Spark check: My friend held one of the sparkplugs to the block and got a good shock: good spark but bad boot, but would this stop the car from running?

Compression test: good, range 159psi - 178psi

Starter fluid: Had someone spray starter fluid, while I started the car. Engine ran as long as both the fluid was being sprayed and the accelerator pedal was being pushed down.

Heard the 1 second buzz that signifies the fuel pump is working.
--------

If it means anything, the car stopped working without any previous symptoms and it was when I tried starting it, not while driving. I also thought I heard a small single thud coming from under the hood at the moment the problem started.

Thanks for any help,
david

PS: What is the small red wire that attaches to the battery?

Don't know - that is not an OE wire - possible power supply installed by a PO.

Have you checked the flywheel position sensor - sounds like that may be your problem . . .

[cth350]

You can't do it thatta way. I just had the exact same set of problems with a 1992 190E 2.6 that I let sit too long. In my case, the car would run on ether easily but not run for more than 3 seconds.

- You need to verify that the pumps (yep, two of them) are both running and that they are delivering the correct pressure. We're talking 100 psi or more, so be careful there.

- Make sure fuel is actually getting to the injectors and then the motor.

My problem turned out to be gummed up injectors. I diagnosed it by pulling a single injector and cleaning it. The car then would actually almost idle, if you can call running on one cylinder an idle.

I built an injector cleaner using a spare fuel pump, spare filter and a couple of fittings salvaged from a VW rabbit (it was handy). That was a lot more fun than having a shop do it for me as I have several CIS cars so the investment of time and energy for the equipment was worth it.

The fuel distributor is probably the most expensive single part in the system, and yes, it can die, but several other parts can die too.

If you find you need one, get it used off ebay. It's a lot cheaper than retail.

-CTH

[marlinspike]

If it is the fuel distributor, you can get them for relatively cheap (relative to the new MB dealer price) on the net. You want to make sure you get the CIS Flowtech one. The Python ones reportedly stink.

[austinite]

What do you make of this tiny bit of information???????????:

The engine runs for one second longer when I run the first "cross my fingers and hope it will run by some miracle" test start (without starting fluid), for a total of 2 seconds. All sequential attempts last for only 1 seconds. Could this one second difference be a clue to anything?

david

[marlinspike]

Hmmm...try turning on the ignition (don't start it, but turn on the ignition) and let it si with the ignition on for like 90 seconds, then try and crank it...anything?

[austinite]

To Richard,

You are on to something. I turned the key like you said and waited to start. It made a difference:

Waiting 90 seconds :
pushing the accelerator pedal increases rpms and engine revs for about 2.5 seconds.

Not waiting or waiting only 0-3 seconds :
pushing accelerator almost makes no impact, engine dies in one second.


PS On my second test, the engine actually ran (after two weeks of shooting blanks) as long as I pushed the pedal, but still won't idle.

Also have new info that might require a new thread.

PPS Mr. Murphy, I don't mean to blow off your suggestion of the Flywheel Position Sensor, it just seems difficult to get to, and with the new info....

[marlinspike]

The fact that waiting 90 seconds makes it run a little bit to me says to me you either have injector problems or fuel distributor problems (the shop should be able to do a leak down test on the fuel distributor and find out for sure whether it's good or bad). When the ignition is on the pump starts to pressurize the system, which makes it last longer because it's put fuel into the lines. This fuel isn't staying in the lines though, so something is leaking pressure somewhere.

[Cams18]

You could have a bad spark plug or its gap is out of wax (too largely open).