intermittent NO START 1977 450SL 135000 miles
 

Dear Friends: I need your guidance and help regarding an intermittent NO START condition that hits me every 30 days or so. Car (when it runs) is smooth, idles fine, shifts OK, power , shifts OK. When key is turned to start, cranks strongly, but dead! I used ether to start and this worked until today, plenty of sweat, no start. It would appear that this is a ignition problem since doesnt even cough with ether squirt. Could this be a relay? Any suggestions appreciated. Engine uses no oil. Regards. Abe G

intermittent NO START 1977 450SL 135000 miles
 

Dear Friends: I need your guidance and help regarding an intermittent NO START condition that hits me every 30 days or so. Car (when it runs) is smooth, idles fine, shifts OK, power , shifts OK. When key is turned to start, cranks strongly, but dead! I used ether to start and this worked until today, plenty of sweat, no start. It would appear that this is a ignition problem since doesnt even cough with ether squirt. Could this be a relay? Any suggestions appreciated. Engine uses no oil. Regards. Abe G PS After sitting for 3 hours, car started tight up!

Can you remove a spark plug wire & see if you are getting spark?

to M> Doc" re No start 450sl 1977
 

Your advice has helped me over the years and much appreciated! 3 hours after the no start, The car started right up! This has been going on over 5 years. The only difference this time was that I had been using ether(spray quick start) Which worked every time BUT not this time. I know when ignition is working the ether works. It didnt work last try, not even a cough led me to believe that it is ignition. Battery strong, starter strong turns engine good rate. It was suggested that either the electric controller or/and a relay were possible causes. Can I get a picture of relay group with id on each? Again thanks for your assistance. Regards, Abe G PS This condition is when car is cold or warm after parking.

Just guessing (easy to disprove) that you have something bad in the FI circuitry if the car pretty much always starts with ether but not on its own.

Nice thing about ether is it gets the car running. Bad thing about ether is that it's hiding any symptoms related to a rich or lean condition.

For now, just turn the key to '1' (turns on the radio, etc). Did the fuel pump start buzzing a bit? (It should only run for a minute and then cut out, so "listen fast").

OK, start the car now (key to position '2'). Keep doing your starts that way (listening for the pump first) and see if it fails to hum once and then not start.

Also, listen to see if it starts humming before starting and never stops humming when you don't try to start it.

Lastly, if it doesn't start but you hear that hum, pull a spark plug along with the wire and see if it's wet with fuel.

HTH -CTH