My 92 300E 2.6 will not start. I hooked up a timing light to check spark and the strobe lights up. I can hear the fuel pump powering up and I also disconnected the main fuel line leading to the throttle body and fuel is running through it OK. Anyone have any idea what the problem is? Could a bad crankshaft position sensor cause this?
Thanks,
Colin
PS Happy New Year everybody!

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92 Mercedes 300E 2.6
86 Plymouth Conquest TSi
79 Chrysler Cordoba (without Corinthian Leather!)

DRIVE FAST TAKE CHANCES!

if there's a spark, then the CPS is fine.

try checking the spark visually. pull out a sparkplug and ground it with the HTleads connected and engine cranked. see also if the splugs are fouled up with fuel. wet plugs cannot make the engine start.

the fuel pressure is good? (at least more than 4 bar).

Dave R here, Staten Island NY.. 1993 300TE 4matic...I have the same condition. If you have spark all the time during a no start condition, your half way home. If you think your problem is fixed just because the engine started today, Im sorry, its not. Test the CPS just to make sure its in spec: 750 to 780 Ohms resisitance, and .460 to .505 AC scale when cranking. Its the smallest round plug on the EZL (Ignition Module, top of drivers side front wheel well,) and its lead is half looped thru a wire tie down strap. Test pump voltage at both pumps, they are wired together from the MAS module. You need 12.5 vdc there solid, or maybe 10.8 vdc while cranking. Hook up fuel pressure guage to end of fuel filter (output side)with a T fitting, I understand you need 70 to 80lbs. PSI there. If you have nowhere near that, change the filter. If still no pressure, block the fuel accumulator return line with a small cut down drill bit or drill rod, and small piece of fresh fuel line with small hose clamps but do not pinch it. An old fuel line will crack on you and leach rubber particles into the fuel system. If the pressure comes up and the engine starts, thats it. If not, the pressure might try to climb a little during cranking, and you eventually might start to get some popping (engine trying to run), then Its probably a bad fuel pressure regulator. (expensive) I wouldnt recommend blocking its return line, without carefully watching the FPG, and be ready to stop cranking when your FPG hits 80psi or so. Over pressuring the fuel distributor body, might harm it. Fuel screen in tank clogged? When you add the T fitting to check the pressure, put a clear line on the T part and into a clear container to check fuel flow first when cranking. Its like 1 quart in about 40 seconds. If you do unscrew that big (drain plug-pickup screen) from the center of the tank,(if you have one), you must have a new O-ring to reinstall it with! If the damn rain ever stops here, Ill check my pump pressure too..... if your going to crank alot, and have a crummy battery, take out 3 or more plugs, it will be easier on your starter....
One or more of the pumps could be bad also. if you have to, take them out and bench test them if everything else has failed. If you do bench em, do it outside for safety and observe the pumps power polarity. Check which is the positive lead before you take em out while cranking. And test them for pressure @ at least 70 to 100psi....Dont let them sit running for more than 5 seconds, you might stall the motor and burn the brushes from over pressure.

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Hi Dave,
Thanks for the advice. Found out the problem was due to a broken adaptor inside the distributor cap. The one that connects the rotor to the front of the camshaft. Car runs perfectly now.
Colin

__________________
92 Mercedes 300E 2.6
86 Plymouth Conquest TSi
79 Chrysler Cordoba (without Corinthian Leather!)

DRIVE FAST TAKE CHANCES!

Although Im not in the car repair business, I have repaired many vehicles in my 35 years of tinkering. I just have to say that I have never seen any failure such as described with any car, nor even heard of a rotor comming off its drive shaft or adapter. On my 300TE the rotor mounts directly to a steel disc that is attached to the camshaft, what is adaptor made out of? This one kills me......

Just as surprised as you, Dave. Wrenched on all my own cars up until this happened. Had to get it towed into a shop, I could not find what was wrong. That's what the shop told me, the steel disc doo-hickey you mentioned had broke, go figure! Just happy my baby is running again.
Colin

__________________
92 Mercedes 300E 2.6
86 Plymouth Conquest TSi
79 Chrysler Cordoba (without Corinthian Leather!)

DRIVE FAST TAKE CHANCES!

what would thaT part be called?

It's called a distributor rotor bracket. aka steel disc doo-hickey! Mercedes part # 1031580840.

__________________
92 Mercedes 300E 2.6
86 Plymouth Conquest TSi
79 Chrysler Cordoba (without Corinthian Leather!)

DRIVE FAST TAKE CHANCES!