420SEL getting 'way too much fuel from its F.I. - PeachParts Mercedes-Benz Forum

retroguybilly · #1 03-20-2008, 08:16 AM

I guess I've screwed up my 420SEL. It started running really badly, and a mechanic told me I needed a new fuel distributor, so I installed one. While I was at it, I cleaned out the EGR passage in the intake. Now it won't start. The F.I. is giving the engine 'way too much fuel, and I can't seem to reduce it with the air sensor plate adjustment. That adjustment screw seems to be stripped out or something; it doesn't seem to want to engage anything when I turn it. When I pull the plugs and crank the engine, I can hear the fuel squirting into the combustion chamber.

Any ideas about what I screwed up, and what I should do to correct it?

Thanks in advance.

david s poole · #2 03-20-2008, 10:40 AM

you have to push the 3mm down and twist until it locks into another 3mm to make the adjustment.it is normal nto have to make a large change[1-3 turns] at the adjustment when you change out the fuel dist.easy way to find a starting point is to jump the fuel pump relay so pumps run all the time and if you hear the injectors sqirting turn counter clockwise until they stop.now you have a starting point.the car should start once you dry out the plugs.

retroguybilly · #3 03-20-2008, 01:40 PM

No, see that's the problem, I've had to adjust it before and I know how to do it, but it doesn't do anything now. I push it down all the way and turn, and it doesn't catch on anything. Or, rather, every fifty to a hundred turns it will catch for a quarter turn. Extremely tedious. Maybe I should lift the top off the fuel distributor and see what's going on under there.