I only ask because a few days ago I started this thread regarding a car I was working on:
http://www.peachparts.com/shopforum/tech-help/350160-1991-300sel-fuel-pump-mas-diagnosis.html
(One caveat, I have to come clean... in that thread I mentioned I was working on the car for a friend. I was actually looking to buy it, but I didn't want to give away the farm to any of you guys who might have also seen the ad... ;) )
So anyhow, this '91 300SEL was advertised as needing a fuel pump and possibly an MAS or other components. When I arrived the car was a dirty mess, the trunk lid was smashed in, and the driver's door was sprung and didn't close flush without a "Fred Flintstone" slam. The leading edge of the door and the rear of the driver's side front fender were munched pretty badly. On the plus side, the interior was perfect, with light blue leather seats, no cracks in the dash, and wood in great condition. It had some very nice Michelins all the way around and service records all the way back to 1990, with no major work done but lots of regular oil changes and tune ups.
The owner was not there when I arrived, but he told me that there was a spare fuel pump in the trunk, and that I was welcome to try to install it and get the car running. I started in on that, and 1/2 hour later I was ready to hopefully hear her fire up. No such luck, dead battery. Daisy chaining two sets of jumper cables together to the tired old Volvo in the driveway brought enough juice to discover that everything electronic inside the car seemed to work, but not enough to crank the starter or get any action from the fuel pump. Jumping pins 1 & 2 on the MAS got the fuel pump whirring, so at this point I'm thinking for $600 and an MAS I may now be interested in the car. I made him the offer, and he accepted. I took the "new" fuel pump off (he wanted an extra $120 for it), and I as I expected fuel came out everywhere (the gauge was showing a little less than 1/2 tank).
I had it towed to my workplace nearby and started in on it. I installed the original pump, charged the battery, and started cranking. Nothing... Pulled the MAS, jumped pins 1 & 2 again, nothing... Tried another OVP I had scored at a junkyard, nothing... Fuel gauge still showing almost 1/2 tank, pump whirring away, we've got spark, uh-oh, what have a I gotten myself into? I'm not a whiz when it comes to electronic fuel injection. Visions of throwing a bunch of hard earned cash at a car that needed a fair bit of bodywork were making me a little nervous... Then I remembered that when I took out the other pump, gas came spurting out. If the pump is doing it's thing now, cracking one of the lines will tell me if this one is also working. Bone dry...
I just happened to have a gas can with me with about 3/4 gallon in it. I poured it in and started cranking... Nothing... Try again... VROOOM! Hi fives with my buddy who is helping me out!!!
So... with all of the original parts in it, the car runs great! I am convinced that the seller didn't realize that it was OUT OF GAS!!! The gauge has seemed to returned to normal operation (I filled her up and I will know after letting it get down to less than 1/2 tank again), and now I know what that little yellow triangle light means... :cool:
Oh, and one more thing... he had a two car garage, and there was a twin axle car trailer in the other space. As I handed him the cash, he confessed that he had done all of the damage to the door trying to get the car on the trailer. Doesn't surprise me considering he didn't even know the car was just out of gas!