First of all. thanks to all the techs that post on this forum for three months of the best MB education that websurfing could ever buy. I've only owned my 300E for ten months and am truly a "babe in the woods" here.

My 1992 2.6 300E has always cranked on the first try and never had even a burp on idle or acceleration even driving in 100 degree weather here in Jax with the A/C on high. The other day it cranked but didn't catch. Not even close to starting.

My mechanic came over and attempted diagnosis. The fuel pump activates with the key. Fuel comes up through the fuel distributor seemingly with appropriate pressure. The "fuel governor" appeared to be leaking, however, so we changed it. No difference. The fuel distributor appeared to have a stuck "piston" in the underneath center which we freed. No difference.

Where should I go from here? Could it still be a fuel pressure problem related to the fuel pump? Or something more sinister?

You obviously checked for fuel, and perhaps went far and beyond what common sense would tell me to do (like replacing governor or removing distributor, before checking for spark).

The competency/judgement of the mechanic is in question (IMHO)

Check for spark!!! (Ignition Coil, sparkplugs, etc...)

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

As stated by Pesuazo, Definately check your ignition system. If the car was running fine, then just all of the sudden wouldn't start, Check for spark at #1 plug by simply removing the spark plug & placing plug (with ignition wire attatched) on top of the valve cover. Have someone crank the car over &
watch for spark at the plug. The spark should be very noticeable. If it doesn't have spark, or has a very dim, weak spark...you know you've got some sort of ign. problem. (ie. bad ign. coil, etc...).
B.T.W.- When dealing with the fuel distibutor- There is a 2"-3" pedestal sticking up just to the left (driver's side) of the fuel distributor. DO NOT try to adjust the hex screw inside this pedestal, unless you are ABSOLUTELY sure of what you are doing...This adjusts the amount of fuel flowing from the fuel distributor & sprayed by the fuel injectors & is a VERY, VERY sensitive adjustment. If out of adjustment, you very likely would not get your car started, until this adjustment is brought back close to where it needs to be...sorry for the lengthy post, hope it helps.

I think the competency of the writer is more in question than my mechanic.
We checked for spark right off the bat. I should have included that in the post. My mechanic specializes in Triumphs, but seems very disciplined about tracking down leads.

My question would be "if spark is present, and fuel is getting to the injectors, what would the next step be?" Could the pump not be putting out enough pressure? And what diagnostic steps should I take if the pump is not a potential fix?

Check for fuel pressure and... when was the last time you change the fuel filter? ALso, have you try to jump start your vehicle lately?
Where in Jax are you?

__________________
J.H.
'86 300E

There are TWO fuel pumps.

Does the fuel metering system recognize electronic control?

__________________
'90 300SE 298k
-300K and it gets put into retirement.
'80 300D 255k Purchased new by family in 1980.

Had a:
1973 220 (gas)
1980 300SD
1992 400E

Could the fuel pump (or pumps) be sending gas, but not enough to ignite?
Since the relay is activating the pump- audible to even me- I assumed that this likely disqualified either pump or relay as the problem?

Can you say more, Fahrgewehr, about the fuel metering system recognizing
electronic control? The pump is sending fuel through the fuel distributor, but I'm not sure if that is what you are asking.

Thanks again

Check this out:

http://www.peachparts.com/Wikka/EngineControls

__________________
J.H.
'86 300E

Ok, you have spark (a good one).
Next I would try "pour gas in the intake technique". If it runs for a few seconds, you know the problem is gas related.

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

Even 100 deg. outside temp is cold for an engine.

I would check to see if the cold start injector is spraying and if it was I would put a coolant temp sensor in it and try again.

If that didn't work then its time to take the gloves off (or actualy put the gloves on) these two things are cheep and comen problems and beond that you may just want to get it over with and have it looked at by a shop that knows what to look for and has the info and tools to do a complete diagnosis.

While this could be a faiulure, it's easy to test the old one in place before spending $ to replace a componant that may or may not be the problem. The coolant temp sensor is the one with two contact pins on the top of the clyinder head. Each pin should have a resistance to ground. If one is open, it's broke. The other two sensors run the dashboadrd gauge and the fans, not critical. somewhere in the forums is a chart for the resistance vs. temperature. a search should bring it up pretty quickly.

Best of luck,

__________________
Norm in NJ
Next oil change at 230,000miles

While I mentioned electronic control, the engine will run without it. Will be very tough to start- will repeatedly die for about 7 attempts. So even without cold start assistance from those related components, the car should eventually start- if you are getting fuel.

Do a search for 'duke2.6' and 'sears multimeter' to learn more about the KE3 system.

__________________
'90 300SE 298k
-300K and it gets put into retirement.
'80 300D 255k Purchased new by family in 1980.

Had a:
1973 220 (gas)
1980 300SD
1992 400E