560SEL not starting and me stumped. - PeachParts Mercedes-Benz Forum

AgieDC · #1 11-18-2007, 12:24 PM

I apologize if I have missed this in a previous post.

I have a '91 560SEL 130k miles. Serviced frequently

While accelerating onto a freeway, hit about 80mph, the engine suddenly quit.

Towed home. Shade tree mechanic (myself) have discovered the following.

Plug spark confirmed (check #1 and #5 cylinders). Gas to fuel distributor and to cylinders is ok and pressurized and confirmed blows gas out of cylinder with spark plug pulled. Rotor turns with distributor cap removed, and seems to be aligned properly with appropriate plug at TDC - having only checked cylinders #1/5 at TDC). Can hear compression at each pulled plug as well (although have not checked compression with gauge.)
Fuel pump activates with key on.

So - have spark, gas and apparent compression. What next?

No clatter from a potential timing chain break. Doubt timing issue as compression blow is consistent at 2 of the cylinders.

Here is my ignorance with this injection engine. I sprayed starter fluid into the air intake and get no "fire"...not even an attempt to start or kick over.

Could this be an issue with fuel frequency timing valve? Or fuel distributor govenor?

thanks for any help and advice

Barn · #2 11-18-2007, 08:15 PM

You did everything I would have done (another shade tree mechanic). I'm also stumped, but thought I'd bump it back to the top.

slk230red · #3 11-18-2007, 09:08 PM

I would check all vacuum hoses, especially the ones going to and from the Idle Control Valve. Make sure they are not cracked/leaking and in good shape and properly connected.

Just a thought.

AgieDC · #4 11-18-2007, 10:06 PM

Thanks for help and encouragement. Am currently looking over vacuum hoses. Still no start. Crazy. chris

MarcusPBoldt · #5 12-03-2007, 03:55 PM

Let me know when you solve this so I can go fix mine!

It's doing the same thing. I have replaced the distributer cap,rotors,and plugs (non resistor) I just now unhooked the main fuel feed to the injection pump and pointed it away from the engine, then I turned the key on and the gas comes out in a nice stream but only goes out 2 feet. I realize this isn't telling me how much pressure is being generated but I am curious if this sounds right? I was expecting the fuel to end up in the neighbors yard but it didn't even clear the engine compartment.

yal · #6 12-04-2007, 10:05 AM

How about the crank position sensor(s)?

david s poole · #7 12-04-2007, 11:08 AM

yal is right,i read your post closely and i see no mention of testing for good spark[from coil to ground] these crankshaft pos sensors[actually sends tdc info to ignition unit]are known to be failing over time not miles.original wire was green---replacement is black.