possibly buy new lines .. Is it possible that stuff got into the new injectors ? Cold start valve replacement new or used? Both regulators good?

 

So I'm posting my project along yours because they are similar in the sense that we are both working with an unknown FD. The issues I'm seeing with installing an FD and the aftermath.
When I cranked for many times, even though the car starts right away because of the cold start valve, nothing was coming out of the fuel lines to the injectors. This went on for many tries, I would say 20. Every time the car would start and immediately stall. And finally after it fired the rpms shot up to 1500rpm and stayed there. So fuel finally reached the injectors and it kept running.

Unfortunately I also swapped in an unknown AFM pot and the ECU is complaining with a code 4. Which is "Unexpected AFM pot value". So I will fix that once the rain stops around here and I should be good to go.

One word of caution for others. Never do FD work with a full tank of gas and the engine on a slight downward slope where the tank gasoline level is higher than your FD. Lessen learned. It was messy.

For your current situation this is what I would do. You have to make sure there is plenty of fuel coming out of your fuel lines and hopefully equally after an FD rebuild. So disconnect all the lies to the injectors and place 8 cars on each and crank away until you get good amount of fuel on all 8. Also connect a Fuel pressure gauge and make sure you are getting the desired 5+ Bar on both the system and the chamber as you are cranking. I was even before the car started so I knew the FD was fine.

 

I'll see about the lines today, waiting for some sunshine and warmth. Most of the injectors are dry, so no contaminants that I can see. By regulators, I'm assuming that you mean fuel pressure regulators. No, I haven't touched those. But wondering since I have 70psi at the FD isn't that an indication that the regulator(s) are good?

 

Hard lines all clear, no obstructions. Some lines had fuel in them, about three, the rest were dry. Cold start valve has pressure as well, it don't think it's operating though as its about 70 here today.

I'm done! That doesn't mean I won't keep tinkering but I'm out of ideas. I rebuilt the FD and made sure everything was clean, all ports open etc and reassembled it like I was doing heart surgery.

What am I offered for my 500?

 

Don't give up so soon. 2 points:

(1) 70 PSI is too low for the system pressure measured next to the FPR. It should be ~75psi even when you are just cranking. That is what mine was. Please let us know if that 70psi is next to the FPR port. Also you would have to make sure your pressure gauge is trustworthy, these things are not that accurate and could easily be off 3-4PSI, which is why one needs a dual input gauge to male adjustments. Also one more side note, when there is air in the system the control pressure is all off. I had the dual pressure gauge hooked up throughout this episode and I could see that the pressure differential was like 0.6bar. Which should be 0.4bar. But that is because of the air in the system. I thought since this was a JY find it must be all wrong and also since the plunger is not adjusted to my car I must set it. So I adjusted the plunger. No help. Then I I adjusted it back to where it was. Remember if this differential is too large no fuel may come out. But that delta must be due to the air and not mechanical. BTW the pressure differential went back to 0.4bar after the car started, so that is another clue.

(2) If there is no fuel coming out of the fuel lines to the injectors you need to keep cranking even if common sense suggest enough already. Remember what I said in my last post. When removed the FP the tank was full and car was inclined down hill. So I had to plug the input and output fuel lines so the fuel would stop coming out of these lines. This must have had the side benefit of at least the lines trapping even more air.

So in your case with even more air in the system I predict that you will completely drain the battery before you get fuel at the injectors. So have a charger ready. Like I said, I charged mine once.

I would also get help and have someone crank as you push the AFM plate up and down to actually force more fuel to those injectors. Pushing the gas pedal may not help, you need to move the plunger manually not the throttle plate. That my help.

Good luck!

 

One more point your cold start valve will turn on if the engine is cold, no matter what the ambient temp is. So it looks like you have an additional problem there. Maybe take care of that first.
If it is working your car should start and then stall just like mine.

 

Dolucasi, I'm measuring the fuel pressure at the port in the base plate of the FD opposite side of the FPR, passenger side of my American Benz. I definitely have gas in the FPR and coming out of it. This afternoon I decided to try my original thought and use my pressurized canister to force fuel through the FD and look at the hard line ports to see if carb cleaner was bubbling through the FD. I used generic carb cleaner, the stuff in the spray can, and sprayed that into the canister and pressurized it to about 70psi. After a few moments I began to see bubbles coming out of the hard line ports, well most of them, along with a dark brown fluid on a few of the ports. It seems that my efforts to clean the FD weren't good enough and I must of had crud in the base plate of the FD, the top half I can guarantee is clean. I'm going to pull the FD and open it back up and attempt to blow through the base plate. I don't want to mess with the adjustment screws, so hoping that getting carb cleaner through each of the base plate ports will be good enough. Also, when. I deflected the air damper I saw a notable increase in the volume of carb cleaner from the ports, well, the ones that weren't clogged.

As for the fuel gauge, I'm using a Harbor Freight special, so I'm guessing the quality is suspect, but it's all I have. I thought 70psi was good from the fuel pumps. I can measure the pressure from the pumps directly, without the FPR inline tomorrow and report on it.

Thanks!

 

I forgot to mention about my cold start valve. Originally, prior to my FD rebuild, I had measured 12V at the CSV but no fuel pressure there. I now have fuel pressure, I loosened the nut and fuel squirted out... Not sure about the 12V but it might not be more than a few milliamps, I'm guessing. You're right, it should of given the engine enough gas to start. Can you please point me to a guide on diagnosing the CSV please, if you have one? Thx!

 

Is it is electrically pulsed to 12V and no fuel spays out, I believe you will have to replace it. Measure the resistance between the terminals and report that please. Most of these activation circuits are in the 8ohms - 20ohms range. And if it is a high resistance, you wilk have to replace it. It is not a serviceable actuator.

When you mentioned you rebuilt the FD I had assumed all of it not just the top half. Seems you will need to open it back up. Also make sure the filters in and around the FD are not clogged up.

- Cheers!

 

2 more points.

(1) Your CSV could be clogged up just like the rest of the fueling system. Maybe apply 12V to it and and pressure force same carburator cleaner into it that may help.
(2) You are measuring your system pressure at 70PSI. That is too low but who knows if your meter is any good. You will need a dual inlet fuel gauge to check things after an FD rebuild as well.
At a minimum at least check your control pressure as well to compare against the system pressure. That could also be a problem. You can check it even during cranking, the car does not have to be running, although it does drift a little after it starts. But at least if it is way off (like almost 70psi, or way low like 60psi) you know that could also be a culprit.

 

Dolucasi,

I did not remove the hex head screws from the base of the FD because of the apparent difficulty in readjusting the exact settings of the fuel flows. The video I mentioned in one of the above posts suggested against that as well. So, I had taken the entire FD apart, excluding those adjustment screws. I'll remove the FD and disassemble it completely, again minus those screws, unless you think otherwise. I will use my pressurized canister to force more brake fluid through the base and make sure that I'm getting flow from all eight ports.

As fas as item 2 above, how do I check my control pressure?

As always, thank you for your help!

 

Dolucasi, just so we're both speaking to the same parts. Here is a picture of my what I'm calling base plate of the FD, the eight surfaces or tops of adjustment screws have not been touched, based on what the video said in terms of messing with the metering adjustments. Each and every channel has been flushed with copious amounts of carb and brake cleaner. When I removed the top half of the FD I did notice that it was full of gas, something that wasn't the case on the first rebuild. Worst case, I think I'm getting closer to finding the issue... I'll once agin blow through the channels and ensure that they're clean. I have no idea where the "brown liquid" could of come from when I used my pressurized canister yesterday, other than from the metering screws, if that's possible. I'm not sure if those screws are actually in the path of the fuel, like a mixture needle, or if they just adjust the height of the little metal caps which ride on the top of each of those screws.

I'm going to take a breath and clean the parts again. I'll be patient and wait until I hear back from you. Worst case, I'll reassemble the entire FD and use my canister again and look at the fuel flow on my bench. The pressurized canister will be hooked up to the fuel inlet, a screw will block off the fuel out flow channel and the connection to FPR. That way I can push fuel into the FD at pressure, 75psi and watch each of the hard line outputs on the top of the FD and see if they all fill up with fuel.
Side note, when I split the halves of the FD all of the spings and dampers were exactly where they needed to be, nothing mis-aligned etc.

 

Hi Fischpj. It is a bit like the deaf leading the blind here, I'm afraid. I have only seen the innards of an FD through drawings and diagrams. I have never opened up a FD, like I mentioned earlier. Which is why I was going to take this opportunity to open my spare up if it did not work. As luck may have it, the JY part is performing even better than my original. After I adjusted the plunger setting everything is great and all the idle and 2500rpm duty cycle is spot on. The car feels like it even has more power off the line, compared to the original which was good as well.

I have taken plenty of pressure measurements etc. on my FD's but never had to open them up which is why I had suggested early on to send yours to CIS-flow tech.

As far as I know, the critical part of an FD rebuild is the internal adjustments which you have not touched. And once you touch them a flow measurement from each injector is necessary like the pro's do it.

So at this point it is best that the deaf not lead the blind here. Also I have never had an 8 cyl FD, so yours may look different than mine.
You are correct in that the adjustment screws should not be touched unless you have the equipment needed to adjust them.

But I may have misunderstood one of your posts. The port by the pressure regulator is referred to as the lower chamber port, which is the control pressure that should be 0.4 bar (~5 PSI) lower than your system pressure. The system pressure is measured at the top near the CSV inlet, and that should be around 80psi, and the lower one by the FPR should be around 75psi. Just wanted to correct myself or the record on this issue.

Independent of your FD rebuild, if I were you, I would tackle the simple part before you finish and test the FD rebuild. That is the CSV. Without it operating you will have a hard time starting the car.
The CSV is a bit of a misnomer. It always operates as long as the engine temp is not at full operating temp no matter what the ambient air temp is. Since you can independently test and fix this, if I were you I would first make sure the CSV is working after you put the FD back on the car. It would be a lot easier to start the car with it working than without.

 

Dolucasi, I did get a quote from CIS-Flow Tech, sadly it was about $900, which is beyond my budget for this car. That being said, I appreciate your candidness and honesty regarding all of this! I did rebuild/reassemble my FD once again, finding nothing wrong in the previous assembly, dirty or clogged. I paid extra attention to the razor thin slits in the central body, the part bridging the bottom and top halves, of the FD. All slits were clean, but I cleaned them again JIC. I reinstalled the FD in the car, connecting the fuel in/out lines and the small line for the FPR as well as the pressure gauge connection to the lower half of the FD. I intentionally left the eight hard lines off of the top of the FD. My theory was if I pressurized my system/FD I "should" see fuel rise in each of the eight holes. When I cranked the car for a few seconds I didn't any fuel in the chambers. I then squirted a bit of carb cleaner in each of the eight holes so I could see if air was coming out, maybe due to the FD purging the internal air. I did see bubbles coming out of four of the chambers, the others held their level but had a tiny bit of rise in the fluid levels. Ok, I next attached the FD end of the hard lines, once again hoping that the lines would be "eventually" purged of air more or less. I got three lines to drip (ooze) fuel while the other five did not after about 15 minutes. I even put paper towels under each of the injector ends of the hard lines looking for wet spots... Deflecting the air plate sped up the fuel coming out of the three "good" lines, but realize that it was at a glacial pace, nothing squirting or even dripping, more like a slow oozing or continental drift. I reconnected the injector side of all eight of the hard lines hoping that three lines might be enough to start the motor, along with some starting fluid. As always, the engine sprang to life for about three seconds then died.

I put my battery on my charger to get it to full power and intend to crank the heck out of it as per your suggestion. I'm trying to maintain perspective on all of this, but it seems crazy that the injectors can't prime themselves. More news as it happens. Oops, forgot to add, I got another pressure gauge and it read 75psi from the bottom of the FD while cranking, so I believe that should be good enough to start the beast.

 

OP Did you ever replace the tiny inline filters you mentioned? Dunno if still available ,but should not be expensive....Maybe just put the whole assembly in carb cleaner and let it soak for 2 days?

Prolly not possible but did you accidentlally reverse the in and out gas lines from the tank at the fuel metering unit?

 

Yes make sure the inlet filter is not blocked. But you did not mention what is happening with the CSV.

Also measure your system pressure too. It needs to be almost 80psi based on your 75psi lower chamber measurement.

Also disconnect your EHA electrical connector for now, we have not seen your engine but it maybe hooked up backwards which would put the FD into fuel cutoff.
Disconnect it and let us know what happens to the fuel flow at the injector lines.

 

WRC & dolucasi,

I finally managed to get my MAS unstuck, I couldn't pull it out of the base/connector. When I shorted pins 1&2 of the MAS connector I got my fuel pump to continuously run. Once it was running I loosened the hard line going to one injector and deflected the air plate a bit and saw gas bubbling/squirting out. I repeated this process another 7 times and got fuel from each of the injector lines. Definitely good progress! I probably should of let the fuel flow a bit more as I was getting bubbling and not a constant stream from each of the hard lines. I'll repeat that process today and make sure the air is out of the hard lines.

I did clean the tiny inline filter/strainer in the one fitting going into the FD, I also blew through it and felt no obstructions. I am however, not sure of which connection is the input vs. the output fuel line of the FD. If you refer to the pic of the FD base plate a few posts above, I believe the connection below what I have labeled as #1 is the input and receives the hard line connection from the FPR, that's where I've placed the fitting with the filter. Please correct me if I'm wrong.

A quick note to anyone who's experienced a MAS not wanting to come out of its socket, there are only two phillips screws holding the connector and MAS in. Remove those two screws and you can pick up the entire connector assembly. This will allow you to carefully use a large flat bladed screw driver to gently work the MAS out of its socket. I'd suggest using electrical contact cleaner and working the MAS in and out a few times then reinstall it with the two screws.

 

Good to hear. You still have some more work to do but you are making good progress. Hopefully someone knowledgeable in 8 cylinder FD's will help you as the 6 cylinder I have does not have 3 ports next to each other like that.

 

Dolucasi, I definitely have promising news! I bled the remainder of the air from the lines and reinstalled the MAS. Upon cranking, the engine sputtered but did not catch. After several attempts I had a neighbor deflect the air plate, not sure what the official name is, and she started, it obviously needed a bit more fuel. The engine did not run terribly well, maybe 5 cylinders, but it definitely ran. I asked him to continue deflecting the air thingie and it once again started. When the air plate was not deflected it did not start. I'm assuming there's an adjustment somewhere that needs to be done, especially since the FD's been rebuilt and probably cleaner than its been in years.

Do you or someone have a suggestion as how to "tune" the engine now?

Thanks, in advance!

 

Well, adjustment is your last thing. First you have to measure.

Measure your duty cycle first. Both at idle and at 2500rpm.
Google for it if you are not familiar with it.

Let us know what you find out. Do not adjust anything before you report your results, please...

 

Does me needing to deflect the air plate matter, because I'm going to need to do that to keep the engine running. Seems like it would mess things up.

 

Indeed it does. If you need to deflect and intervene in this process of idling you can not really do anything.

At this point you need to do a proper fuel pressure check. For that it matters less that you are aiding by pressing the plate. But you need a dual inlet meter or at the least two fuel pressure gauge's that are calibrated to each other.

I would not do anything until you do this. It is possible your rebuild did not go according to plan. There is a rubber diaphragm in there that is normally replaced in a rebuild. I assume you did not reach that. It is possible that diaphragm is breached. You should read up on that.

 

I should add that my original FD was replaced at ~150K miles, when the car was only 25 years old. The car would not start and it was rather catastrophic.
The car never sat for extended periods and driven daily/weekly. So you may well have a similar situation. Pressure tester is your friend.

 

Dolucasi, I completely rebuilt the FD, new o-rings and diaphragm, the only thing I didn't touch were the eight fuel adjustment hex screws. I've rebuilt the FD on my 380 with no issues, I was just as careful with this one. As you suggested, I'm beginning to suspect the fuel pressure. I'll see if I can get another gauge today.

 

Good to hear. Indeed, check the pressure. Also I forgot, did you make sure all the injectors are not gummed up. You can force fluid like alcohol into them individually at about 40psi they are supposed to spray a nice pattern at that pressure or slightly above it. I suggest alcohol as who wants to deal with toxis gas fumes and alcohol evaporates eventually. Maybe there is a more appropriate fluid for this, I don't know.