Last night at a very inconvienent time of 12:30am (well, I guess it was today), after the car had been running for about 5 minutes, I was braking to stop at a light and all of a sudden, ALL of the warning lights went on and RPMs went to zero. No warning, no odd sounds, no funny performance. When I came to a full stop, I shut off the car, and tried to restart it. I got plenty of electrical power, meaning the lights don't dim when I try to start it, all the lights came on and the radio worked. The engine tried to turn over, but it didn't start. So.... I pushed the car while someone else steered (what a heavy f*&king car!!). Once we got it into a parking lot, I tried to restart it. Same thing, all the warning lights come on, engine cranks, but does not turn over. The warning lights even come on with the key turned to the accessories position without trying to start it.

A few weeks ago I had a similar problem where the car wouldn't start. Did not have a problem with the warning lights coming on. I had the relay, filter and pumps replaced. After that, my car ran great. Then, I started to have a problem with the RPMs dropping once the engine turned over. With the car in Park, the RPMs would fall down to 5 or so, then jump up to 10. Once I shifted into drive or reverse, the RPMs would come down to 7ish. It would run slightly rough until the car warmed up (just a touch under 80 degrees) and then it ran perfectly. Most times when starting, I had to give it a little gas because it seemed like the car was going to stall out.

The exhaust seems to have a bit a gas smell to it. It was like this before and after the relay and pumps were replaced.

When it starts (this is after the new fuel pump etc.) I hear some kind of thump sound. From the driver's side, it seems like it's coming from some where on the right side.

Mileage wise, I get about 300miles/tank.

Not sure if this matters, but I have a kill switch installed whereby one has to have the left turn signal on for the car to start.

Based on what I've come up with from reading this site, it seems it could be one of these problems:
- relay
- pump
- 02 sensor
- I suppose, I could have just run out of gas, but the guage was indicating a bit less than half full after driving close to 200 miles.

86 420SEL w/aprox 130K miles

Here's the link for comments about the problem the first time it happened.

intermittent no starting 420SEL