pictures are for your future work.. anytime you take it apart or troubleshoot take pictures

 

So you did the wrong thing trying to re adjust a new EHA. Should not have messed with that. It is true that "sometimes" the EHA needs to be fine tuned to your old FD but the starting point should not be to adjust it at T zero,
Especially back then you did not know how well the old one was adjusted anyway. You can not tell from just driving the car.
That is water under the bridge now and may not be your problem anyway but to get back to the original EHA settings you will need a caliper.

I have done this in the past and know that out of the Bosch factory the unit comes with the proper spec. You measure the distance between the EHA surface and the depth of the adjustment screw. Please look that up on line and set it to that exact height.
I'm sure you will need to fine adjust it later but this should at least get you to a good stating point.

What I would do first is to put the leaky EHA back in but I'm afraid you messed with that too trying to count turns. If you had not touched it, it would work fine temporarily to at least gauge if the new EHA was your problem.

Keep us updated and we will try and help from afar.....

 

Thank you dolucasi, for the kind words and support. I did a bit of searching and found the "default" setting of 6.6 mm to be the most quoted factory setting. I found that number here. I'll get to that this morning. Are there any recommended ways to cleaning the internals of the fuel distributor, I did notice that my damper flap seems sluggish, and wondering if it's gummed up. I also found several several notes about an internal fuel filter in the FD, also referred to as a fuel restricter. I don't mind tearing things apart if there's a point and a rebuilder kit available...

Thank you again!

 

I pulled the EHA, which had gas in it, and re-adjusted the metering screw to 6.6mm and replaced the EHA back on the car. Sadly, no change. The car does run for about 5-10 seconds with liberal amounts of carb cleaner... As I mentioned, the EHA did have gas in it, I'm saying this towards the end of trying to find where the fuel is getting stopped. Could the entire FD be clogged from sitting about two years now? The only otherFD I've rebuilt, was a 1981 380SL, and that was pretty straight forward.

Thoughts please?

 

I have never rebuilt an FD, but from what I've heard it can be a tricky operation. Especially one that is gummed up from sitting for 2 years. All I know is the best way forward is to send the unit to CISFlowtech who are experts in this. They will ship a unit that is flow tested etc. so you know you will end up with the proper FD.
Anything else may be experimentation. Also uneven fuel flow to all cylinders is murder on the engine because you can fuel wash your cylinder walls and cause long term damage. So the FD is the heart of your engine and probably should be left to the experts.

 

probably worth watching

 

Dolucasi, thank you, I'll look into the rebuild service. I am tempted however, to take a look at the little inline fuel filter behind a fuel inlet in the FD first, I've ready that that can be clogged and cause issues.

 

Vesiadog, thank for that video, it helped! I remember seeing that one a long time ago.

 

If you are going to send it to CISFlowtech it is not a bad idea to open it up first and take a peek inside to satisfy the curiosity. You may find surprises in there.

 

Dolucasi, actually I was going to one crazy thing before I consider sending it off. Honestly, it's probably going to be more money than I can spend right now. It's what I think is a total Hail Mary for the FD. I have a metal canister that can be pressurized and hold and dispense liquid under pressure. I was thinking of filling it with carb cleaner and then forcing, gently, the cleaner through the FD via the input port. I was outside working on the car earlier and I pulled several of the hard lines from the top of the FD. About half squirted gas as I loosened the hard lines, and half didn't. When I went to the other end of the loosened hard lines and disconnected them from the new injectors I put in I found all of them dry, aka no gas. It sure does seem like the FD is clogged and I really don't think I can hurt it by passing carb cleaner through it under pressure.

Thoughts?

 

You can try it to see if there is any improvement but that will not be a long term solution even if it shows a bit of improvement. For a case like yours I actually have an extra FD I pulled from a junk yard. I was going to experiment with it. Actually on one of my cars I need to replace the rubber boot between the FD and the MAF because it has a leak.
I plan to first throw in this extra FD to make sure it works. If it does, I will keep it as a spare. If not I will get to open it and experiment with rebuilding it.

This does not help you I know but if you can get a spare from a JY, I would recommend it.

I suspect you will end up opening up the FD in the end.

 

Dolucasi, That's great, especially where you're open to a bit of experimentation and I definitely agree this would be a short-term solution. I have rebuilt one FD in the past, you just need to be very methodical, keeping parts together in the orientation they're originally in. I did find a good video on the rebuild, showing the things that need to be measured before the rebuild. Here's the link.

I'll take pics of the process. Thank you!

 

Pics would be great for the community! Also I'm curious before you re adjusted the EHA back to the 6.6mm height did you measure what it was?

 

I'll definitely take pics and post them! I didn't measure the set screw before I recalibrated it, but I did turn (tighten) it until it was seated. It took less than two turns, so I'm guessing it was at about 7-7.5mm. It seemed to me that it was almost closed, way too close to being completely seated. Just my impression, but after many many years of rebuilding standard carbs, it felt too tight.

 

Your post inspired me so I looked up and found a couple of FD's in my parts cabinet. One was a complete AFM, AFM pot, FP regulator, FD that looked very clean and perhaps serviced at some point.
The AFM pot was very bad so I replaced that. The entire unit looked clean inside out, normally they look decrepit in the Junk Yards. Anyway, I will swap this in to my W201 currently under restoration and see if I can even start it. Fortunately, the set-up in the car already works pretty well but just needs a new AFM boot.

 

Wow, I'm honored to have inspired you! I just ordered a rebuild kit for my FD, $75 and worth it. I've already removed the FD from the car. I did note that that the three screws that attach the FD to the air damper/throttle body were hand tight, this isn't good as it all needs to be air tight. Even if it didn't clog up it wasn't mounted correctly.

I'll do the disassembly and cleaning as soon as I get the rebuild kit, probably 7-10 days and take pics.

 

Patient is on the bench. I'll let you know how it turns out. Looks super clean for a JY find.

- Cheers!

 

Wow, that IS clean. Best of luck!

 

BTW, I purchased a couple of rubber boots at the dealership. Surprised they still carry them. Your other option is Vaico aftermarket, I assume they make them for 6 and 8 cylinder engines, they do for 6.

A word of caution, Mercedes updated the rubber connection to the IACV it seems. This is the part that always cracked up over 30 years (probably shorter in a 8 cyllinder engine as it would have to sit closer over the engine and therefore gets hotter)
What they did was the make the rubber thicker there and made the walls pretty thick at the connector.

Long story short, they must have also updated the white plastic that bit accepts the rubber hose as it's diameter needs to be smaller now.

So heading to the dealership today to get the updated plastic (hope they have that)

I doubt Vaico updated theirs but I do not have one to check. I will post a picture of this in the future.

 

I hadn't planned on pulling off the entire FD assembly, just the top part is sitting on my bench right now. As I recall I had to replace the rubber bellows/boot on my 81, it's probably best that I be thourough and remove the boot as well and look for cracks. You're inspiring me as well. Thank you for the info and motivation!

 

Since you are in there this is a good time to replace the rubber boot and perhaps the hoses around it. I'm doing the opposite, since I need to replace the rubber boot, may as well check out the JY find fuel delivery system.

- Cheers!

 

Not sure where you are with your rebuild but here is where I'm at with the rubber boot change and JY find FD/AFM/AFM-pot/EHA/pressure regulator swap/check.

Rubber boot: The new one from MB is so pliable there is no way I could slip the entire unit on. I tried contraptions etc for 2 hours. I had to take the AFM plate that is secured to the plunger with a center bolt out. Actually it can not come out I just disconnected it and with it out of the way I could slip the new boot on in 2 minutes from the inside of the air intake.
New set-up: Because there is so much air in the system, it took forever to start. It would start right away due to the CSV spraying fuel but immediately die. There was actually no fuel coming out of the injectors. I had to charge the battery once as it was starting to get weak. I must have cranked at least 20 times.

I hooked up the pressure gauges and noticed that I had good system pressure and decent chamber pressure. I was about to give up and literally the last crank started it and it ran.
Once it warmed up though it started to misbehave and throw an EC code and now it is cycling in idle like these cars always do when some sensor is way out of expected value..

I did replace the AFM pot and it is very good shape but needs an adjustment. Will try that tomorrow. I should have just adjusted it before I put it in. It can be done with the assembly out of the car and would be much easier. Lesson learned.

So my feedback to OP is after the FD is opened up to air it could prove to be very difficult to start the car as like you also noticed all that air has to come out, and it may take many many cranks.

Another point I should make is that I was wrong about the change of the AFM rubber boot and it requiring a new coupler. Yes they changed the design but the new coupler I got from the dealership was the same. It was very difficult to insert and I would high recommend fitting the rubber hose to the boot BEFORE inserting it in. Otherwise you are asking for trouble.

- Cheers!

 

Wow, it sounds like you did a lot of good work and more or less wound up where I am now! I skipped the removal of the rubber boot/base plate because some of my soft rubber air lines are no longer soft and I didn't want to break more...

Ok, rebuilt the FD, no problems and no spare parts left over!!! I reinstalled the FD with no issues and to make a long frustrating story short, it behaves exactly the same as it did before the rebuild. I do exaggerate, the cold start valve now does push gas, it didn't before. About half of the o-rings in the FD were almost completely gone or in pieces when I pulled it apart, so the rebuild was needed.

I pulled the lines from a few injectors and saw that half have gas and the others don't. I think you discovered that there is air in the injector hard lines. I would of thought that the 70psi would of forced the air out and replaced it with gas... seems like it might not, based on your experience. I'll give it another go tomorrow after I go to the parts store and get more starting fluid. It's got to be the air in the lines, right? There's not much else it could be! Thoughts?

Kinda past frustrated... Anyone want a nice 91 500sl reasonably cheap?

 

Trying to follow but I admit between the post I have gotten lost a few times.
Questions: Have you cleaned out all lines ? If I remember correctly you had block lines ? ok good luck

 

Hi, sorry about the confusion. Yes, I cleaned each of the hard lines out but I'm thinking that the air now trapped in the lines is preventing the fuel from getting to the injectors. That's just a theory, but running out of things it could be. To summarize all of the repairs done to date:

• The engine runs briefly with carb cleaner or starting fluid in the manifold, seemed to be a fuel issue. Had a leaking EHA and replaced it, but messed up the metering settings by attempting to turn the screw to match the number of turns found in the old EHA. Went ahead and used a member's suggestion of 6mm plunge depth for the screw.
• New fuel pumps, accumulator and fuel filter. 70psi at the FD
• New Bosch injectors on all 8 cylinders, including the rubber seats for them
• Rebuilt the FD, now getting fuel to the cold start valve and two or three injectors, suspecting air trapped in the fuel hard lines.

Tomorrow, planning to attempt to used a vacuum siphon, hand pump, to draw fuel through the fuel lines to each injector ensuring that there's gas at the injectors. The engine still runs with starting fluid. Stumbles without starting fluid, but does not start. Battery fully charged.

Frustrated and contemplating a nice glass of whiskey.