Some of you may remember that I posted about a ’91 300SE that I bought as a parts car for my ’82 300SD. The problem is that the ’91 is just too nice for a parts car—the interior is immaculate and the underbody is free of rust—just too nice.
However, the SE doesn’t run. It sat for several years, and the gasoline turned to molasses. I removed and cleaned the tank and replaced the fuel filter and pump with new ones. I get 85 psi from the fuel pump to the engine bay.
Now, first off, let me be sure I am using the correct terms---
The “fuel accumulator” is the can with a spring-loaded diaphragm and is located near the fuel pump and fuel filter.
The “Fuel Pressure Regulator” ( FPR) is another can with a spring-loaded diaphragm, but it is located in the engine compartment, next to the Fuel Distributor.
Is that much correct?
By the way, the engine runs very smoothly if I pour some gas into the intake manifold/ air meter, so I am assuming that ignition and mechanical condition of the engine is not the problem.
With that 85 psi going into the FPR, I see nothing at the Fuel Distributor. Am I correct is believing that mans the FP is bad?
Is there any way to test them—using either vacuum or air pressure? I can pull another one from a junker at the local automotive dismantling and recycling center, but how can I be sure it’s a good one? I don’t mind buying a new FPR AFTER I know that everything else is good. There is just no end to the $250 to $300 parts that you can throw at these things. I’d like to have some confidence that “this” will fix it, but until it runs long enough to test drive, I am hesitant to spend that cash.
Is there a way to test them?

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1982 300SD " Wotan" ..On the road as of Jan 8, 2007 with Historic Tags

One other thing...
Is there a "work around" to replace the FPR just for temporary testing? How about if I fabricated some PVC pipe with a screw lid that I could put some fuel in, and pressurize to get fuel to the Fuel Distributor? I'd probably have to plug the fuel return lines to the tank, but could something like this be made to work?

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1982 300SD " Wotan" ..On the road as of Jan 8, 2007 with Historic Tags

Re:
Need Fuel system help 1991 300SD, Bosch CSI

You are talking about a 300SE, are you not.
There may be a crime scene here, but the Bosch system is CIS. Not CSI.

You have the Accumulator and FPR identification correct.
The FPR however, is downstream of the FD, in the return circuit.
As a check for fuel flow in the FD,
1) Loosen the six fuel injector line fittings in the top of the FD.
2) Bridge the fuel pump pins in the pump relay socket so that the pump will run continuously.
3) Push down on the air meter plate. Does fuel flow out of the loosened fittings?

If you're getting 85 psi then your accumulator and fuel pump are in excellent shape. If you measured that pressure at a correct port in the fuel distributor then you FPR is likely good enough to get the car to run.



Your system pressure is supposed to be between 75-80psi


more info:
http://w124-zone.com/downloads/MB%20CD/W124/w124CD1/Program/Engine/103/07.3-1603.pdf


to check if your fuel injectors/fuel distributor is good what you may want to do is set up something similar as in this video (I did that on my SE to check my injectors/fuel dist):


https://www.youtube.com/watch?v=6yrwqspHhak

Yes--you saw the typos--It is indeed a 300SE with continuous injection.

You say the FPR is DOWNSTREAM of the FD??? wow THAT may be the issue. Fuel line from the pump ( on this car) went to the fuel cooler and then to the FPR, then to the port on the forward side of the FD. The fuel return line is connected to the port on the rear side of the FD. Are you saying that the lines are reversed???
If only it would be that simple.... ( You just never know what a "basket case" might be).

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1982 300SD " Wotan" ..On the road as of Jan 8, 2007 with Historic Tags

Nice video of your injector test setup. I have pulled one injector and used the air compressor to force some fuel thru it, and the spray was very fine. After I make sure it runs, I might cobble together something like you did to quantitatively test the flow and pattern in all. But first I want to have it running.

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1982 300SD " Wotan" ..On the road as of Jan 8, 2007 with Historic Tags

not mine but still good

UPDATE AND REPORT

So I swapped the fuel lines around and tested the pressures. At the cold start port I had 5.4 Bar, and at the lower chamber port, I had 5.0 Bar --so the difference was 0.4 Bar---all numbers right on the money!!!

I decided to pull the injectors and take a look at the patterns---not good. Only 2 of them looked OK ( the only 2 I had previously looked at) the other 4 just dripped. I soaked them for a while and then ran some fresh fuel mixed with fuel system cleaner thru them. The patterns all eventually improved--not perfect, but should be good enough to run and let me check out the rest of the systems.
Hopefully, tomorrow it will run!!!
Thanks for the help.

You know, I saw one of those Bosch videos describing the generic CIS. I noted that the FPR was on the downstream side of the system. I thought it "odd" that my car was hooked up backwards, but not being familiar, I decided to leave it alone, and that was most of the no-start problem---at least, at this point, I think it was. Tomorrow will tell the tale, (I hope).

OK--one (simple) problem...why do the wipers sometimes drag slowly across the windshield as I crank it over? Bad ground??

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1982 300SD " Wotan" ..On the road as of Jan 8, 2007 with Historic Tags

Thursday Update
I flushed the injectors. Not a one had a consistent pattern, but all delivered some fuel. I re-installed them, hoping they would dribble enough fuel to let the engine run long enough to warm up.
It did start right up, but died after 20 seconds. It would re-start but not run consistently. I think I have to decide if I want to invest in a set of new injectors if there is any hope of it running.
What is the value of a M103 and its transmission?

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1982 300SD " Wotan" ..On the road as of Jan 8, 2007 with Historic Tags

Try running with the pump relay bridged; if that does not help the fault(s) may be in the FD. The system has been inactive for a while and all the metering components stand to be partially plugged with gummy stuff. Disassembly and cleaning of the FD may be in order.

this causes most of the rough running cases:


1. Remove the hard buildup on the posts of the inside of the distributor cap with a hard tool (I have to do this every 2 months, same engine)

2. measure the resistance of your ignition wires 1k ohms just the wire, 2k if you measure from inside the distributor cap to plug end, wire to the coil no resistance

3. If you don't have records then replace the ignition coil (insulation inside breaks down and you can't test it, $25 ebay one works)

4. remove the plugs and see what they look like, clean

The M103 fuel distributors rarely go wrong and because of the cost/difficulty of reassembly it's the last thing you should do.


You can check for even delivery like I posted in post #4

I recently worked on my 2.3-16v replacing the oil cooler lines. What a total pain. Required removing the intake manifold. Once i put it all back together and started the car, it barely idled. It ran fine before i took it all apart. My son inspected my work and he noticed I had not reinserted the injectors with air tubes correctly. That was the problem. Make sure the injectors are properly seated with the o-rings and all providing a good seal. Check for any vacuum leaks. good luck.
Henry

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63 190d (sold)
69 220D (sold)
69 280SL (sold)
76 BMW 2002 (sold)
86 190E-16v (Demised at Laguna Seca Turn 9)
87 300SDL (sold)
87 300SDL 135k
87 300TD 280k (sold)
95 E320W 211k
95 E320w 111k
05 C320 4matic
06 E320 CDI 90k (Totaled by a texting 19 year old girl in a nissan)
2013 GLK 250 Bluetek 4MATIC

Thanks for the responses.
It appears that the problem is not the FD. I have good fuel flow all the way to the injectors at all positions of the air flow plate with the fuel pump real contacts bridged.

I think the major problem is still the injectors, themselves, and I will replace all injector tubes and seals when (if) I get new injectors. I understand that air leaks cause performance issues. I will also do a complete ignition tune-up at thay time. But first I need to be certain that the basic CIS works and doesn't need a $ 1000 in parts just to find out that the transmission is FUBAR---until it moves under its own power I can't be sure---even though, historically, the transmission is not a suspect item.
I believe the FSM has the procedures for checking all the electrical sensors and actuators even on a non-running engine, so that is the next objective

Again, THANKS for your help. Its good to know I am not alone--even though (because of COVID-19), I am pretty much alone.

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1982 300SD " Wotan" ..On the road as of Jan 8, 2007 with Historic Tags

I knew that stuff got real when they closed the fine wine and good spirits stores


Anyway back to m103s


1990 and newer M103 suffer from cracking/breaking ignition rotor flanges:


FYI Broken M103 camshaft rotor adapter distributor rotor bracket 1031580840


It's about $20 and mine was heavily cracked and almost broke off:


https://www.pelicanparts.com/More_Info/1031580840M253.htm?pn=103-158-08-40-M253&bt=Y&fs=0&SVSVSI=3092




And while you're in there take a good look at the "suppressor plate".


If it's cracked/has burn marks/looks tired then your spark will jump to the engine block instead of going to the cap post: