Classic/Antique Car Repair: 1977 me/bz 450sl, air screw, adjustment screws


Question
QUESTION: when cold starting the car if it doesnt start right away on first attempt [even then barely ideling]i smell gas and it wont start again smells flooded

ANSWER: Hi Dennis:

Many times on old Benz (I have one of them myself), you may has a stuff automatic choke. If the idle is not high, then it is mostly one or more foul plugs. The best cure for a new foul plug is take it out on the interstate and blow her out at 70 to 80 MPH. If she haven't been tuned in awhile, then it may be time for a good tune up. Plugs, Air filter, carb adjustment, etc.

When starting her up, hold the pedal to the floor (Don't pump it). If it doesn't start in a few seconds, release the pedal and re-apply it once more. If it won't start after a few seconds after that. Stop the process and let her sit a few seconds, then try again without pressing the gas pedal.

By-the-way, if she is a diesel engine, I hope its not cold where you are. That would surely affect starting. Hope this help.


---------- FOLLOW-UP ----------

QUESTION: could you tell me a little more about the choke like if you can clean it or can it be replaced or can it be set higher or lower as far as gas mixture strenth

Answer
The choke linkage can stick on older cars. So, a can of WD-40 sprayed on the linkage and cleaned will usually fix that. However, if the choke sensor is bad, it would need replacing. Trying cleaning first. In terms of fuel mixture, that is usually a carb adjustment. My benz is  little newer that your (Early fuel injection), so I not sure where the air/fuel adjustment screws on your benz, but I'm guessing you have either two spring-loaded screw on each side of the carb or one on either side. You can always tell the fuel screw because it is next to the accelerator linkage. The other screw is the air screw.

If you think you are running rich, then you can try to adjust the carb yourself. Could be a bit tricky. The best method is two tighten both screw completely. The loosen both screw 2 1/2 turns each. Then start her up. If she starts, you can adjust either more fuel or more air from there. Revive her up a few times first to she how she is running. Each time you make an adjustment, revive her up again and let her idle back down. You will need to have the breather cap on during this process.

One other possible issue, If you have any air leaks in the intake area, you will never get a good fuel to air mixture. The air filter and intake housing must be tight and leak-free. Otherwise the carb adjustment will just be a wait of time. Hope this helps.