hey all, i just got a 89 420sel with 100k. car has the shakes and no power about 80% of the time. the other 20% of the time it's fine. i bought a new (used) fuel distributor but i don't know how to change it. i disconnected all of the brass lines going into it but can't pop it off the top. checked the archives for 20 minutes but no instructions found. please help. thank you.

 

Hi miishmiish,

I can help you with this. But please give me some background information before you get started. Also I would like to mention a few things about theunit before you begin.

1) Are you reasonably sure the problem is in the fuel distributor? I'm asking because other things like leaky vaccum lines, clogged fuel injectors,and faulty sensors can cause fueling problems as well.

2) Fuel distributors can indeed go bad at 100k miles, especially if fuel quality has been poor, or if the car has been in storage. Rust and fuel additives can collect in the unit and wreck it.

3) A special note before you begin. Be sure to cap all the fuel lines and ports when you disconnect them. Many of the fuel components are made out of plain steel (rather than stainless) and will begin to rust immediately when in contact with the air. Rust, in my opinion, is the major problem with FI systems.Capping the lines will also reduce the fumes, reducing headaches and fires.

4) Taking into consideration the previous statement, how did you find a "good" "used" fuel distributor? They tend to simply "go bad" if they have been sitting around without fuel in them.I'm just giving you the warning.

5) DONT take the fuel distributor apart. Everyone says this, but here's why. Inside there is a very thin membrane (as thin as a condom), it tends to stick to one of both halves, and if it tears during dis-assembly, it is done.

6) To remove it, there are torx screws on top of the unit that have to be removed.

7) No response. It's one of those things that could be shown to you in 30 minutes, but would take 50 pages to write.

Blue

 

i got it on ebay for 200 bucks with a 30 day warranty. the guy had a bunch of them. i am reasonably sure as the car went through a major service last year but was only driven 500 miles since. the whole ignition system was changed, timing chains, and some gaskets. i had this issue before on a 380sl but i paid a mechanic. i want to do it myself this time.

once i remove the torx screws, it just comes right out? will the new one just slip right in? thanks for all of the tips. i am in the middle of it all and stranded without transpo until it's fixed.

 

Yes, if you have disconnected the fuel lines and removed the torx, it should come off easily by hand.

Blue

 

i lost the heads off of all three screws. they are so stuck in their place that my tool went through the grooves like butter rendering my tools useless! do you have any tips for how i get these screws out?

 

yeah, this brings up an oldgripe ihave about the electroplating on ALLmb fasteners and hardware.

Ok, do you have an electric drill and a 1/4 inch or 7mm drill bit, and some masking tape? You can tape or plug all the ports, to keep metal shavings from getting in them. Then drill the top of the screws until the head separates from the shaft. After all heads are removed, slide the dist up and off, then use vise-grips to remove the shafts. But, you said you were stranded, and I bet you don't have extra FI screws in your toolbox.

Blue

 

thats what i was thinking. i already started trying to create new grooves and i ripped through those as well....junk!!! i will just rip the heads clean off and try to replace those three screws at the hardware store in the morning. just to confirm so i don't make a mistake, i want to use the drill bit to completely shred off the heads of the three screws and the fuel dist. will simply be able to be lifted out? there is no threading on the inside of the three holes in the fuel dist.?

 

If you have a very sharp small punch or a pointed tap, you can "spin" the screw out by using the punch to start a small "punch-mark" on the outer rim of the screw, and then tapping gently with a hammer, in such a way to spin the head of the screw in the counter-clockwise direction. This actually has a pretty good success rate in skilled hands.

Blue

 

Last message late.

Drilling the screw heads:

1) Tape or cap every port and opening. I'm dead serious.Have a vacuum ready to clean up; keep the shavings under controlor they will ruin your year.

2) Use the hand drill by drillingin the old hex-hole of thescrew head.Use light pressure. Don't be aggressive, just let it cut. The drill will begin to cut the head away, and it will follow the old hex-hole in the head. Keep it straight. When the drill removes the last bit of the head, you should be able to feel it, so pay close attention. If it goes a little past the head, it is still ok, but dont go an extra 1/8 ,for example.

3) after all crappy screwheads are drilled, do some immediate and thorough clean-up. Lift the dist of the old screwshanks; it will slide straight up if the heads were removed completely. Screws are not threaded into dist.

4) use vice grips to remove scrapscrew shanks.

Blue

 

The shank of the screw measures .193 ".
So any drill between .193 and .250 would work.

Blue