88 560sl ingition switch changed now what?

[qsprn]

A while back my 1988 560sl started killing while being driven. It would start right up and run well but quit every so often. Sounded like the classic ignition switch problem.
I had a mechanic replace it. It ran great for 20 miles. My wife wanted to drive it and it quit in the driveway. She put it back figuring it was just not warmed up.
I just tried to move it. It stalled backing out of the garage. Now it starts right up but stalls almost immediately. Starts again and stalls again. What did we screw up?
Thanks for your help
Bill

[tecqboy]

Perhaps the problem was not the "classic ignition switch", but the "classic fuel pump relay" instead. Point is that there are many classic things which can cause this symptom. At least it's gone from an infrequent problem to one which occurs often enough so it will be easier to track down. This vintage vehicle is relatively simple electrically. Get the electrical schematic diagram and use a volt meter to trace out the circuits for fuel and ignition.

[qsprn]

Originally Posted by tecqboy

Perhaps the problem was not the "classic ignition switch", but the "classic fuel pump relay" instead. Point is that there are many classic things which can cause this symptom. At least it's gone from an infrequent problem to one which occurs often enough so it will be easier to track down. This vintage vehicle is relatively simple electrically. Get the electrical schematic diagram and use a volt meter to trace out the circuits for fuel and ignition.

Thanks, I will do that. I had begun to wonder if I didn't have a fuel issue
all along when it repeatedly stalled today, but thought that was too simple.
bill

[qsprn]

I believe the problem is solved. It turns out it was probably the fuel filter
all along. The old one not only needed changing it was the wrong one.
I was once told there is a difference between a mechanic and a parts changer. I'm no mechanic.
For this problem, I recommend trying the following order: 1) Fuel Filter. 2) Fuel pump relay (which is behind the glove box). 3) ignition switch.

Of course, I chose to go backwards.
Thanks for all the help.
bill