HELP 1991 300SL won't start

[Marc-1]

Wen't out for something to eat at a pub and 2 hours later decided to leave for home. The car wouldn't start! Turns over, has spark and when I disconnected the fuel lines on both sides of the fuel filter there is lots of fuel squirting out. Still will not start. Tried dumping a little gas in the air inlet and nothing!! Checked under the distributer cap and cleaned everything there and it looks fine. Took a plug wire off and held it near a ground and got good spark. Will check in the morning to see if it skipped time but I doubt it. I think it has something to do with the fuel injection unit. OR it could be the camshaft location sensor. How do I test this? How do I diagnois these things? PLEASE HELP
Car ran fine going to the place. What could possibly go wrong while it is off and not cooled down yet? Just running out of ideas.
Thanks in advance

[tecqboy]

I own a 1991 300SL and so I am very intrigued by your delima. Please post a follow up when you find the problem. I haven't had this happen to me...so far. I think you have already tried everything I'd have checked. Does anybody know if you still get spark with a bad position sensor?

[Marc-1]

Ok... check this out!!
I ordered a new disributor cap and rotor on ebay 3 years ago. When I got it I installed it. The thing was the same as the one I took out (only new). Well, well, well,
I drove this car in MA and then to FL and all over FL for three years... Wrong distributor rotor!! The inside of the rotor where the disributor cap makes contact was completely missing. I put the new one in and tried to start it. BEFORE the last cylinder hit top center the car was running. It purred. However, I tried to look at the electrical connection of the camshaft possition sensor (as it leaked a little oil from there) and when I went to pull the wire off the whole sensor just fell apart. $140.00 for this little thing, located just above the thermostat, just to the right of the dist. compartment, and in the side of the cly. head. It has two sockethead cap screws, (allen head) in it and is black plastic. If any of you are working on the thermostat or near this thing... be carefull. One bump and you're out $150 real quick. The car does start with this broken but I only let it run for 5 seconds and I have a new one on order. Oh and here's some pertainant info... I called the dealer for this part got a price then called every parts dealer in the book and ALL the parts dealers were significantly higher priced than the dealer!! Go figure!!

[Gilly]

So how do you account for the fact that you said you had spark???

The car wouldn't start! Turns over, has spark and when I disconnected the fuel lines on both sides of the fuel filter there is lots of fuel squirting out. Still will not start.

Gilly

[Marc-1]

Simple... It's what's called secondary spark and this is after it jumps from the cap to the rotor and then to the plug... well by this time the spark is weak, erratic and LATE. Totally retarding the time it should fire.

Now that I replaced the camshaft position sensor and the rotor it works as it did before but I always noticed a vibration and when I bring the RPM's to 2000 it studders or otherwise I can hear it in the exhaust. Now that the electric parts are new I'm curious as to whether one of the injectors is clogged. Hmmm... I will take all the plugs out and lay them on the valve cover and have a helper turn the car over so I can be sure that all six fire correctly as well as produce a good clean spark, then it's off to checking the injectors. (At which time I will most likely need more help)

[Gilly]