1999 CLK 430: Cranks but won't start
 

MB 1999 CLK 430 ran last summer but sat over the winter and now will crank but won't start. I can hear the fuel pump engage when I turn the key into the second position. The fuel filter leaked after repeated attempts to start it so I replaced it - but no luck starting. I have 1/4 a tank of fuel (gas confirmed at the fuel rail). The battery is new and fully charged. I have weak spark on the driver's side and couldn't see any spark on the passenger side (but only tested one plug).

I'm considering replacing the crank position sensor (CPS) as the next step.

Any suggestions would be appreciated.

The CPS would be the best bet for now.
Otherwise, an inexpensive tool such as spark plug tester - has an acrylic tube where one can see the spark and intensity. This is because you mentioned a weak spark.

Being ignorant, is that engine with a distributor or coil-on-spark?

Thanks. And it’s cool-on-spark

My first avenue whould be to check the fuel pressure on the rails. You changed the filter. If you search the forum, you will see many people have confused the 4 tubes on the filter and installed it incorrectly and no fuel gets to the engine. Are you getting any firing at all? ...doubt it's CPS..almost always associated going bad when engine has been hot.

Hi Cindyclk, last summer I had many overheating issues and issues restarting after the car being too hot, which is why we turned to the CPS after the fuel filter (however, the CPS is stuck and has become an absolute nightmare to remove). I will check the tubes to the fuel filter again after we manage to get the CPS out

Well you didn't mention that...yes the CPS is a pain to remove...again, do a search on CPS install...only way I was able to do it was with a 1/4 inch flexible extension w E-8 socket.

Problem solved:

CPS replaced (what a nightmare), fuel filter replaced, and one leaking line to the fuel filter replaced. Starts up and runs now.

HOWEVER, I’m running rough at idle (like a shaking) and can hear (but not feel) the rumble from that roughness as I drive. I’ll try to describe this better after my next drive. Any ideas?

Perhaps confirm all cylinders are firing? And that there are no occational misfires and go from there?

On older cars with bigger engines it could be a combination of sources. CVS aystem and all gaskets in OK condition so there are no bigger air leaks?

Glad that tyou got the CPS done..PIA!

The shuttering sounds like bad MAF (many times throws an oxygen sensor error code...but usually turns out to be the MAF)...I would first start by being sure that the rear housing of the air filter unit is securely seated in the MAF housing.... (remove air filter, lower rear and seat onto MAF housing..and only then lower front onto clips)...also be sure that the vacuum hosing is not cracked...if all else fails, buy a new OEM unit...get from https://www.autohausaz.com/?gclid=Cj...saArtgEALw_wcB