Have a 1982 240DL. Long story shortened...took it to a mechanic ..he wanted $500 to replace my fuel injector o-rings and do a tune up (button, cap, plugs, plug wires). I am a novice mechanic so be easy on me :-)

anyways...here is the long version of the story...

symptoms started at mail fuel pump (under car not in tank) started buzzing loudly for a couple of days and would jerk when accelerating... I figured it was because I chose the wrong place to get gas and ended up with watery gas (even tho I always get premium)... I added some dry gas with no relief. Eventually I got through the tank and went to a much better gas station and filled it up again... not 5 minutes after the problem totally went away.

so, I am doing fine... then all of a sudden another problem starts... I turn the key to start the car... goes fine... drive about 10 miles... park, come back 10 mins later, and go to start the car... I notice that I don't hear the fuel pump buzz when I turn the key. The engine turns over, but seems like the fuel pump isn't getting electricity all of the time. After what was probably 30 minutes of trying... I finally hear the buzz of the pump and it fires up like it was brand new.

Well, I got freaked out, and by this time I realize I had better have someone check it out... so take it to the mechanic and he checks it out... he said that I need to replace my o-rings for the fuel injector(s), and that I need a tune up... then he tells me it will come to $496.00 after tax!! So, I decided that I will fix it myself for that much... the mechanic I guess never saw the problem with the fact that it wont start after it has been driven a little while.

So, I went to the nearest Auto Parts Store and bought the o-ring kit, spark plugs, spark plug wires, fuel filter, air filter, distributor cap, ignition rotor... all of which was $100 roughly.

Here are my questions... and I would sincerely appreciate any help.

1) How hard is it to replace the o-rings in the fuel injector?
a) I believe I have the LH Jetronic because it seems like I only have one injector...

2) does anyone have any idea what would be causing the problem with the fuel pump (assuming thats what I am hearing) only coming on intermittently?

Thanks so much for any help you can give!!
Jason

p.s. I have replaced the following within a year
main fuel pump (under car), wiring harness, and the engine was replaced (now has 140k on new engine.)