SLK/R172: 380 SL won’t start
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Newbie
Joined: Apr 2023
Posts: 7
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From: USA North Carolina
1984 380SL
380 SL won’t start
Hi, I am new to this forum and I am looking forward to contributing and getting some help too.
I recently purchased a 1984 380SL It has been seating since 2014 and I am trying to get it to start. New fuel tank and strainer, new fuel hose, new; pump, filter, fuel accumulator, in-line filter at the fuel distributor, new injectors - holders and seals, working cold start valve, new fuel relay and new battery. Engine cranks but will not run. I have fuel pressure at The input of the fuel distributor and at the cold start valve, the round silver plate next to the fuel distributor is hard when pressed down ( sorry, I do not know it’s proper name) evidence that I have fuel pressure according to some YouTube videos. If I remove all of the injector lines off the top of the fuel distributor and press the round silver plate, gas pushes out of the ports on top of the fuel distributor. If I spray starting fluid in the cold start valve port, the engine starts and stay running as long as I keep spraying. QUESTIONS:
1. How and where do I check for proper fuel pressure? How many PSI or Bars should it be? 2. Why is my cold start valve not energizing? Even when I have the coolant temperature sensor disconnected? 3. Fuel pressure regulators (2) other than checking for a rapture diaphragm evident by seeing fuel drip from the vacuum hose port, how do your check these? Mine are not dripping fuel, so I am suspect they are good. Any ideas? Any help is greatly appreciated. Thank you for reading my long message. Lastly, any suggestions of what fuel gage kit to buy?
I recently purchased a 1984 380SL It has been seating since 2014 and I am trying to get it to start. New fuel tank and strainer, new fuel hose, new; pump, filter, fuel accumulator, in-line filter at the fuel distributor, new injectors - holders and seals, working cold start valve, new fuel relay and new battery. Engine cranks but will not run. I have fuel pressure at The input of the fuel distributor and at the cold start valve, the round silver plate next to the fuel distributor is hard when pressed down ( sorry, I do not know it’s proper name) evidence that I have fuel pressure according to some YouTube videos. If I remove all of the injector lines off the top of the fuel distributor and press the round silver plate, gas pushes out of the ports on top of the fuel distributor. If I spray starting fluid in the cold start valve port, the engine starts and stay running as long as I keep spraying. QUESTIONS:
1. How and where do I check for proper fuel pressure? How many PSI or Bars should it be? 2. Why is my cold start valve not energizing? Even when I have the coolant temperature sensor disconnected? 3. Fuel pressure regulators (2) other than checking for a rapture diaphragm evident by seeing fuel drip from the vacuum hose port, how do your check these? Mine are not dripping fuel, so I am suspect they are good. Any ideas? Any help is greatly appreciated. Thank you for reading my long message. Lastly, any suggestions of what fuel gage kit to buy?
Thread Starter
Newbie
Joined: Apr 2023
Posts: 7
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From: USA North Carolina
1984 380SL
A quick update, wile researching this issue further online, I found a seemingly great resource in YouTube. I will share who once I experience for my self his help and product. I am buying a fuel gage from him with manuals, procedures and additional resources when dealing with a KE Jectronics issues. The next step is to measure the system and control fuel pressure. The results will indicate the step to follow. I have convinced my self that I will need to rebuild the fuel distributor and probably the warm up valve, probably sooner than later. Will keep you posted
Thread Starter
Newbie
Joined: Apr 2023
Posts: 7
Likes: 0
From: USA North Carolina
1984 380SL
here is an update on my no start condition. I received the fuel gage, great product. I did the system and control pressure test as well as the leak down test on the fuel system and here are the "disturbing" results. both the system and control pressure are at 10 bar. there is no change in pressure when I turn of or on the valve on the test rig on the WUR side the specifications calls for System 5.0 - 5.6 Bar cold and Control .5 - .8 bar cold. why I am getting 10 bar for both its still a mystery. A it of good news, the leak down test failed, pressure should stayed no less than 2.5 bar after 30 minutes and it dropped to .5 bar after 15 minutes. I discovered the hose that connects form the output of the fuel filter to the line that goes to the front of the vehicle was leaking. I replaced the hose and the leak down test stays at 2.8 bar at or after 30 minutes. Since, I rebuilt the fuel distributor and the disassembled, cleaned and reassembled the WUR. I am still at 10 bar for both pressures.
Next step, to find out why my system and control pressure read 10 bar. Any suggestions is greatly appreciated. thanks
Next step, to find out why my system and control pressure read 10 bar. Any suggestions is greatly appreciated. thanks
Thread Starter
Newbie
Joined: Apr 2023
Posts: 7
Likes: 0
From: USA North Carolina
1984 380SL
I am starting to wonder if anyone uses this forum or my challenge is not of interest. for al is worth, Update - I discovered I had a clogged fuel return line causing the 10 bar pressure for both system and control. the clogged returned fuel line issue has been fixed. I run the system, control and leak down pressure test and I believe my results are within range. currently, System Pressure is 5.2 Bar, Control pressure is 1.4 bar @ 70 degrees ambient and leak down test is at 2.8 after 30 minutes. after reconnecting everything to run the car, I tried to start it and it cranks, but does not run, still. I could not hear the fuel pump run when the switch is turned on, so I direct connected the pump and crank again and it cranks but does not run. if I spray starting fluid the engine starts and stays running as long as I spray starting fluid. I think I have a couple of issues now; 1. power to the fuel pump under normal start condition, I replaced the fuel pump relay at the beginning so I need to check for voltage at the pump under normal crank and start condition. 2. Cold start injector and cylinder injectors not spraying. I have new injectors, seals, holders and air tubes. I also have a known good cold star injector. I voltage checked the cold start solenoid, it passed and I have also rebuild the fuel distributor and cleaned inside out the warmup regulator. I need to check again if I have pressurized fuel at the cold start valve and if I see fuel feed out of the top of the fuel distributor where it feeds the injectors, when I gently pressed the air flow plate. I think I am missing something here, I hope that someone out there can redirect me as needed. I am disappointed but not deterred that after all of the work I have done on this fuel system, is still not running.
Newbie
Joined: Mar 2015
Posts: 2
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From: Charleston, SC
1984 380SL
Hey Jairo. Shame nobody added any insight. I'm wondering if you identified the cause to your no start issue? I've been experiencing a similar issue with my 1984 380SL. It ran fine one week and then would not start the next.
Newbie
Joined: Jun 2024
Posts: 12
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SLC 43 AMG
Jario, this is the SLK/R172 forum. Sounds like you have a SL. Perhaps that is why you have not got much response.
The 380SL was a two seat convertible made from 1980-1985 part of the R107 series. It was not part of R172 series. There is an R107 form that you probably would get better information from.
My guess is that it is the WUR. Good luck.
The 380SL was a two seat convertible made from 1980-1985 part of the R107 series. It was not part of R172 series. There is an R107 form that you probably would get better information from.
My guess is that it is the WUR. Good luck.
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