I recently purchased a 1988 560 SL that had been sitting about a year. I replaced the plugs, wires, rotor & distributor cap. It still idles a little rough, BUT the big thing is that sometimes it starts REALLY hard when warm. I'll pull in to a store, go to leave & crank & crank before it starts. Then the next time it will start right off??? One hint- sometimes it starts but seems to be running on just a few cylinders, then stalls. Any ideas?? Sometimes pumping the accelator seems to help, but I know that's it's fuel injected...

 

if 117 got leaky injectors, it will take time to burn the fuel that was accumulated on the top of piston/s. it will run rough at start and eventually runs fine after a few seconds.

 

It's not really that way. It idles rough pretty much all the time, sometimes worse than others. Starting the same way. Maybe 5 times, it will fire right up, then one time it just doesn't want to start. I'll drive a mile or so, park, come out in a few minutes & it won't want to start. the only other symptom is that sometimes it'll begin to start, then die. Then i really have a hard time with it.
Thanks for the input. Would a vacuume leak do that??

 

vacuum leak only make the engine shake wildly.

 

How was it running before you replaced the plugs, wires, rotor, and cap?

 

It was running rough all the time. The tune-up smoothed it out for the most part, but it still is a little roug idle. The bothersome part is the hard starting...about 1 out of 20 times. I ran injector thru the gas tank, but that didn't seem to help. Would changing the fuel filters help?

 

Replacing maintenance items never hurts. A clogged fuel filter can certainly cause those problems.

Gas gets really gunky after a year, especially if no stabilizers were added. Throw another can of Bud, er, injector cleaner in there when you replace the fuel filter. Use a different brand of cleaner. They all have slightly different formulas.

 

/i think i found my problem..... I went to change the fuel filter and found that the gas line out of the filter was leaking. The car ran great when I first did a tune-up but then has been getting progressively worse. It finally started after about 10 minutes of cranking. I noticed a puddle under it & found the gas leak. Evidently it has been getting worse and finally showed itself. I'm sure that improper pressure to the injectors would cause my problem. Getting a new fuel line today.

 

Hey, cool... that you found the problem, that is... I hope.

 

#$&*&% I changed the fuel filter, fixed TWO leaky lines. Car started right up cold. Drove to the store, everything eas fine. Left OK. Next stop....wouldn't start.