Previous commenter is correct - operating pressure should be 2 bar and residual pressure around 17/18 psi so no leak. I have a leak in mine and the pressure goes to 0 instantly when switched off.
Thanks for sharing. I believe your D-Jet has a pressure of 32psi with the engine running and the residual pressure of 16psi is about right as well. And I think your car has no leaks in the fuel circuit.
Hi Ed. You have answered me a few days back, I’m looking around in your videos trying to troubleshoot my car. I talked with Pierre Hedary and he said injection leak is unlikely and he gave me two other options to look into: check valve being old or losing pressure at the regulator. But what’s weird for me now that I watched your video is that even after disconnecting the fuel pump and emptying the system from fuel, your car started on first crank. Since my hot starts are excellent, I’m starting to suspect something else: I’m not losing pressure (I’m, but within what’s normal), but simply when I cold start, the pump can’t pour enough fuel to the engine in one try. So my pump could be bad ? To be fair, even when I rotate the keys twice, it doesn’t start as fast as yours. Yours started like it was a hot start. I’m impressed and confused. If these info give you a new idea of troubleshooting I’ll take it. Love your videos!
Yes it does sound like for some reason you don’t have sufficient pressure and/volume at cold start. It could be all of those things Pierre suggests, but if running pressure is OK I would have thought it’s not the regulator. How is the fuel filter, could that be restricting flow?
Go to home depot or ?? buy a gauge that read around 60 psi , get a braze barb fitting to attach a piece of hose , with 2 clamps .disconnect the cold start valve , attach the hose to the rail , you are ready .Also looking at that video , you must organize the spark plug wires away from any fuel line . There is a fire waiting there [ common ]
such a beautiful car! must run perfectly because of its elegance, this is a real Carl Mercedes Benz concept with Robert Bosch D-Jetronic Injection Masterwork system . first check the pressure regulator . see which fuel pump is installed? Original Bosch with 2 bar? Is that a nice V8 sound from a raceway alloy 350 slc engine :) ? Good Work this is realy "Made in West Germany" ! Thanks Germany
Yes I think you may be right, someone may have fitted either in ignorance or because they could not find the correct one. Possibly explains why pressure is on the high side.
@@classiced1416 I had to use a K-Jet pump on my 350 SL many years ago until I found a replacement D-Jet pump. It works but the extra high pressure stresses the fuel system up to the regulator. The regulator does its best to keep pressure to approx 30 PSI. I also believe the D-Jet pump has a higher flow rate than the later pump.
@@ClassicCarMotorsport The D-Jet injection requires an exact system pressure of 2 bar. Everything else cannot work properly. Then check the closing angle of the contacts from the ignition
yes definitely with 4,7 - 5,0 bar . it will only destroy the pressure regulator . make a new video when the car drives. only the 350s had a good V8 sound
Was the issue the injector seals did you figure it out I have the exact same problem and can get it to keep ruining It does run but once I press the gas pedal it shuts off
So I slightly misspoke in the video - replacing the injector seals improved the vacuum sealing, but loss of fuel pressure was probably caused by the injectors themselves leaking, because the fuel pressure is in the fuel circuit, rather than the air.
The original fuel pump has a maximum of 2 bar + - ... It seems as if the pump is not suitable. Someone has exchanged it? You can also adjust the pressure regulator, but it will cause problems later. Best of all everything is original. Very nice sound. these are cars unmistakable :P it is no problem to check the fuel pump , original bosch ?
Hi yes it had a 6 bar pump on it when it came in, I couldn’t find an original D Jet pump for reasonable money but someone who knows D Jet well recommended a 3 bar pump that is similar so I fitted that (I did another video on the subject). I turned the regulator down a bit as well and car seems happier now!
Sorry I wrote a reply and then realised I was thinking of another video! For the pressure test, the correct way to relieve pressure is remove fuel pump relay and then crank. Because my relay board was very stiff and difficult to remove the relays from, I just disconnected the electrical wires to the fuel pump and cranked - that’s what I meant by ‘disconnect’ no need to remove any fuel pipes or anything. The connectors can be removed with a small socket.
Previous commenter is correct - operating pressure should be 2 bar and residual pressure around 17/18 psi so no leak. I have a leak in mine and the pressure goes to 0 instantly when switched off.
Thanks for sharing. I believe your D-Jet has a pressure of 32psi with the engine running and the residual pressure of 16psi is about right as well. And I think your car has no leaks in the fuel circuit.
I hear it's the 1972 Carl Mercedes Benz with Bosch components. Great work !
Hi Ed. You have answered me a few days back, I’m looking around in your videos trying to troubleshoot my car.
I talked with Pierre Hedary and he said injection leak is unlikely and he gave me two other options to look into: check valve being old or losing pressure at the regulator.
But what’s weird for me now that I watched your video is that even after disconnecting the fuel pump and emptying the system from fuel, your car started on first crank.
Since my hot starts are excellent, I’m starting to suspect something else:
I’m not losing pressure (I’m, but within what’s normal), but simply when I cold start, the pump can’t pour enough fuel to the engine in one try.
So my pump could be bad ?
To be fair, even when I rotate the keys twice, it doesn’t start as fast as yours. Yours started like it was a hot start.
I’m impressed and confused.
If these info give you a new idea of troubleshooting I’ll take it.
Love your videos!
Yes it does sound like for some reason you don’t have sufficient pressure and/volume at cold start. It could be all of those things Pierre suggests, but if running pressure is OK I would have thought it’s not the regulator. How is the fuel filter, could that be restricting flow?
there are also alternatives to a pump from pierburg, they work reliably. they have to go back to the original 2.0 bar
Go to home depot or ?? buy a gauge that read around 60 psi , get a braze barb fitting to attach a piece of hose , with 2 clamps .disconnect the cold start valve , attach the hose to the rail , you are ready .Also looking at that video , you must organize the spark plug wires away from any fuel line . There is a fire waiting there [ common ]
such a beautiful car! must run perfectly because of its elegance, this is a real Carl Mercedes Benz concept with Robert Bosch D-Jetronic Injection Masterwork system . first check the pressure regulator . see which fuel pump is installed? Original Bosch with 2 bar? Is that a nice V8 sound from a raceway alloy 350 slc engine :) ? Good Work this is realy "Made in West Germany" ! Thanks Germany
Hi Mate, that looks like a K-Jet fuel pump on that '72 SL.
Yes I think you may be right, someone may have fitted either in ignorance or because they could not find the correct one. Possibly explains why pressure is on the high side.
@@classiced1416 I had to use a K-Jet pump on my 350 SL many years ago until I found a replacement D-Jet pump. It works but the extra high pressure stresses the fuel system up to the regulator. The regulator does its best to keep pressure to approx 30 PSI. I also believe the D-Jet pump has a higher flow rate than the later pump.
@@ClassicCarMotorsport
The D-Jet injection requires an exact system pressure of 2 bar. Everything else cannot work properly. Then check the closing angle of the contacts from the ignition
yes definitely with 4,7 - 5,0 bar . it will only destroy the pressure regulator .
make a new video when the car drives. only the 350s had a good V8 sound
Was the issue the injector seals did you figure it out I have the exact same problem and can get it to keep ruining
It does run but once I press the gas pedal it shuts off
So I slightly misspoke in the video - replacing the injector seals improved the vacuum sealing, but loss of fuel pressure was probably caused by the injectors themselves leaking, because the fuel pressure is in the fuel circuit, rather than the air.
The original fuel pump has a maximum of 2 bar + - ... It seems as if the pump is not suitable. Someone has exchanged it? You can also adjust the pressure regulator, but it will cause problems later. Best of all everything is original. Very nice sound. these are cars unmistakable :P
it is no problem to check the fuel pump , original bosch ?
Hi yes it had a 6 bar pump on it when it came in, I couldn’t find an original D Jet pump for reasonable money but someone who knows D Jet well recommended a 3 bar pump that is similar so I fitted that (I did another video on the subject). I turned the regulator down a bit as well and car seems happier now!
Hi Ed , How did you disconnect the fuel pump safely?
Sorry I wrote a reply and then realised I was thinking of another video! For the pressure test, the correct way to relieve pressure is remove fuel pump relay and then crank. Because my relay board was very stiff and difficult to remove the relays from, I just disconnected the electrical wires to the fuel pump and cranked - that’s what I meant by ‘disconnect’ no need to remove any fuel pipes or anything. The connectors can be removed with a small socket.
@@classiced1416 Thanks Ed, thats really helpful!
minut 1.20 minutes everything can see the pipe ist not the original bosch with 2.0 Bar