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1979 450 SLC R107
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Discussion Starter · #1 ·
Hello,
May I please get your assistance on the following issue with my Fuel Distributor (FD)?

My 1979 450 SLC is having a hard time during a cold start, so based on information provided by this community/forum, it was an issue with fuel system; it was recommended to adjust the fuel delivery system by operating in the 3mm adjustment screw to the point fuel would come to the top of the ports, but I noticed that one of the ports fills up faster than the rest; this could be my source of cold starting issues; any recommendations on how to tackle this issue?
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I have done following things to the fuel system:
Replaced:
  1. Fuel pump
  2. Fuel lines
  3. Fuel filter
  4. Fuel accumulator
  5. gas tank strainer
  6. Cleaned fuel tank
  7. The fuel distributor was sent to CIS rebuilt (according to the previous owner)
Thank you in advance for your assistance and time.
 

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1976 450SL, 1992 190e 2.3, 1984 300D turbo, 1966 VW bus
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1,074 Posts
warm up regulator. Was this also sent to CIS Flowtech? Post a photo, it should be obvious if it looks new.
 

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Hello,
May I please get your assistance on the following issue with my Fuel Distributor (FD)?

My 1979 450 SLC is having a hard time during a cold start, so based on information provided by this community/forum, it was an issue with fuel system; it was recommended to adjust the fuel delivery system by operating in the 3mm adjustment screw to the point fuel would come to the top of the ports, but I noticed that one of the ports fills up faster than the rest; this could be my source of cold starting issues; any recommendations on how to tackle this issue? View attachment 2712428
I have done following things to the fuel system:
Replaced:
  1. Fuel pump
  2. Fuel lines
  3. Fuel filter
  4. Fuel accumulator
  5. gas tank strainer
  6. Cleaned fuel tank
  7. The fuel distributor was sent to CIS rebuilt (according to the previous owner)
Thank you in advance for your assistance and time.
Did you first test the fuel volume from the pump? Did you also check the WUR and control pressure with a CIS fuel pressure test kit?

Is this something that is only happening at cold start?

Have you rebuilt or replaced your idle control valve?

What is your outside temp when this happens?
 

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Premium Member
1979 450 SLC R107
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20 Posts
Discussion Starter · #5 ·
Did you first test the fuel volume from the pump? Did you also check the WUR and control pressure with a CIS fuel pressure test kit?

Is this something that is only happening at cold start?

Have you rebuilt or replaced your idle control valve?

What is your outside temp when this happens?
Yes. I was having issues with a hot start but when I changed the fuel injectors this problem went away. I checked the idle valve, and it checked good. I also checked the voltage at the WUR (10.8v)and idle valve (11.6v).
The temperature was about 90.
 

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Premium Member
1979 450 SLC R107
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20 Posts
Discussion Starter · #6 ·
Did you first test the fuel volume from the pump? Did you also check the WUR and control pressure with a CIS fuel pressure test kit?

Is this something that is only happening at cold start?

Have you rebuilt or replaced your idle control valve?

What is your outside temp when this happens?
Thank you for your assistance and time.
I have not checked the volume of fuel from the pump. I wonder how I can do that. I am sorry I forgot to mention in my post that I got a rebuilt WUR from CIS flowtech . I have checked the idle valve and its voltage; all good here. The outside temp was like 85-90.
 

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Premium Member
1980 450 SL
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476 Posts
Hello,
May I please get your assistance on the following issue with my Fuel Distributor (FD)?

My 1979 450 SLC is having a hard time during a cold start, so based on information provided by this community/forum, it was an issue with fuel system; it was recommended to adjust the fuel delivery system by operating in the 3mm adjustment screw to the point fuel would come to the top of the ports, but I noticed that one of the ports fills up faster than the rest; this could be my source of cold starting issues; any recommendations on how to tackle this issue? View attachment 2712428
I have done following things to the fuel system:
Replaced:
  1. Fuel pump
  2. Fuel lines
  3. Fuel filter
  4. Fuel accumulator
  5. gas tank strainer
  6. Cleaned fuel tank
  7. The fuel distributor was sent to CIS rebuilt (according to the previous owner)
Thank you in advance for your assistance and time.
I think it could depending on how bad this is. I don't know but it should be much better if it was recently rebuilt.
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If several of the lines are not getting fuel while cranking then after running there is positive pressure in the system.
Mine looked like this after I rebuilt it and set the distribution. Flowtech has good reputation and you don't have first hand knowledge that is was rebuilt.
 

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Premium Member
1979 450 SLC R107
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20 Posts
Discussion Starter · #8 ·
I think it could depending on how bad this is. I don't know but it should be much better if it was recently rebuilt. View attachment 2712506 If several of the lines are not getting fuel while cranking then after running there is positive pressure in the system.
Mine looked like this after I rebuilt it and set the distribution. Flowtech has good reputation and you don't have first hand knowledge that is was rebuilt.
Thank you JHTX for the reply.
So, what you are saying that the only way to solve this issue is by getting the FD rebuilt (the WUR was purchase from CIS Flowtech); you are right I dont have the first hand knowledge that the FD rebuilt even if the previous owner claimed, he had it rebuilt by FlowTech, but he also stated that he did other things to the fuel system, which I found out later that they were not done (cleaned gas tank, replaced fuel pump, filter, and accumulator).
 

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Premium Member
1976 450SL, 1992 190e 2.3, 1984 300D turbo, 1966 VW bus
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1,074 Posts
Thank you JHTX for the reply.
So, what you are saying that the only way to solve this issue is by getting the FD rebuilt (the WUR was purchase from CIS Flowtech); you are right I dont have the first hand knowledge that the FD rebuilt even if the previous owner claimed, he had it rebuilt by FlowTech, but he also stated that he did other things to the fuel system, which I found out later that they were not done (cleaned gas tank, replaced fuel pump, filter, and accumulator).
I just had my FD rebuilt by Flowtech and I think you should be able to tell by the outside appearance. If from Flowtech all of the screw in fittings should be yellow zinc plated. Also the FD body will be painted matte black.
If you inspect carefully I would think you should be able to tell. Could still be under warranty from Flowtech ?
 

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1979 450 SLC R107
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20 Posts
Discussion Starter · #10 ·
I just had my FD rebuilt by Flowtech and I think you should be able to tell by the outside appearance. If from Flowtech all of the screw in fittings should be yellow zinc plated. Also the FD body will be painted matte black.
If you inspect carefully I would think you should be able to tell. Could still be under warranty from Flowtech ?
Thank you natejgreene9871; it seems like all the feedback that I am getting from you and other members is that the FD will need to be rebuilt; as you can see in my first post the picture of the FD is like cast iron black color, and to be honest with you I did not see any yellow marks on the screw in fittings; I will call Flowtech and see if they can assist.
Once again thank you.
 

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Outstanding Contributor , Bob's Your Uncle!
83 280 SL- 5 speed-The PIG
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Thank you natejgreene9871; it seems like all the feedback that I am getting from you and other members is that the FD will need to be rebuilt; as you can see in my first post the picture of the FD is like cast iron black color, and to be honest with you I did not see any yellow marks on the screw in fittings; I will call Flowtech and see if they can assist.
Once again thank you.
Ask for Larry. Super helpful.
 

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Premium Member
1980 450 SL
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476 Posts
Thank you natejgreene9871; it seems like all the feedback that I am getting from you and other members is that the FD will need to be rebuilt; as you can see in my first post the picture of the FD is like cast iron black color, and to be honest with you I did not see any yellow marks on the screw in fittings; I will call Flowtech and see if they can assist.
Once again thank you.
If it was rebuilt you don't know how much contamination was in the rest of the system and how long it was run after it was rebuilt. Fuel Distributor should be the last item put on after. New fuel filter, pump, strainer, etc. You don't start with the fuel distributor unless you just want roll the dice on having to clean it again.
I am not saying this is your issue there may be others but just that a rebuild FD should not have this much uneven distribution. Fuel distribution is it's job!
 

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Thank you for your assistance and time.
I have not checked the volume of fuel from the pump. I wonder how I can do that. I am sorry I forgot to mention in my post that I got a rebuilt WUR from CIS flowtech . I have checked the idle valve and its voltage; all good here. The outside temp was like 85-90.
First step is to disconnect the fuel line ( I use the sending line but I believe the correct way is the return line- I use the send line because I want to know if my pump is in good order).
Disconnect the ignition coil wire (in center of distributor cap).
Let the send line go into a container of at least 1 liter.
Turn the car over for 30 seconds continuously.
Measure the fuel in the container. It should be between 750ml and 1 liter. I think 1 liter is what the manual calls for.


So the WUR shouldn't be the problem. I asked about temp to know if it were cool enough to engage the cold start valve. It is not.



On your engine there should be a fuel pressure regulator either on the driver side of the distributor, the rear of the distributor (I am tlalking about the fuel distributor- not the ignition one) or both.
If you can run your car for several minutes, 5-20, and disconnect the vacuum lines to the FPR- if you see fuel leaking then there is a vacuum leak in the FPR itself. It happens more often now as corn gas does not mate well with the older vacuum seals.

From there begin checking your fuel distributor as others have mentioned here. The single best way to do that is disconnect all lines going into it: NOTE- I have found that it is easier to disconnect them at the fuel injectors first or you may be fighting an alignment issue getting them back in. NOW if you do that first you can put 8 shot glasses beneath them (one per of course), energize the fuel distributor by placing the key in the "on" position. Do this for about 8 seconds. Check the gas in the shot glasses. if it is not even then the FD is not putting out an even flow. The second way to check this is to go ahead not and disconnect the injector lines from the FD. Energize the FD again ( really the fuel pump is being energized). Standing over the FD press down on the fuel distributor plate. Fuel should come up evenly at all 8 ports. If not you have an internal fuel distributor problem. This will require a rebuild.

ONE MORE THING- BEFORE disconnecting the fuel injector lines go head and pull all the injectors, place them each in a shot glass and energize the system again. Have someone do this so you can check to see if the injector spray in a conical A(cone like) spray. This is necessary for proper running of these engines.
 

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Yes. I was having issues with a hot start but when I changed the fuel injectors this problem went away. I checked the idle valve, and it checked good. I also checked the voltage at the WUR (10.8v)and idle valve (11.6v).
The temperature was about 90.
Check the resistance of the WUR- ohms. It should be between about 18 and 24 ohms resistance.
 

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Premium Member
1979 450 SLC R107
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20 Posts
Discussion Starter · #16 ·
First step is to disconnect the fuel line ( I use the sending line but I believe the correct way is the return line- I use the send line because I want to know if my pump is in good order).
Disconnect the ignition coil wire (in center of distributor cap).
Let the send line go into a container of at least 1 liter.
Turn the car over for 30 seconds continuously.
Measure the fuel in the container. It should be between 750ml and 1 liter. I think 1 liter is what the manual calls for.


So the WUR shouldn't be the problem. I asked about temp to know if it were cool enough to engage the cold start valve. It is not.



On your engine there should be a fuel pressure regulator either on the driver side of the distributor, the rear of the distributor (I am tlalking about the fuel distributor- not the ignition one) or both.
If you can run your car for several minutes, 5-20, and disconnect the vacuum lines to the FPR- if you see fuel leaking then there is a vacuum leak in the FPR itself. It happens more often now as corn gas does not mate well with the older vacuum seals.

From there begin checking your fuel distributor as others have mentioned here. The single best way to do that is disconnect all lines going into it: NOTE- I have found that it is easier to disconnect them at the fuel injectors first or you may be fighting an alignment issue getting them back in. NOW if you do that first you can put 8 shot glasses beneath them (one per of course), energize the fuel distributor by placing the key in the "on" position. Do this for about 8 seconds. Check the gas in the shot glasses. if it is not even then the FD is not putting out an even flow. The second way to check this is to go ahead not and disconnect the injector lines from the FD. Energize the FD again ( really the fuel pump is being energized). Standing over the FD press down on the fuel distributor plate. Fuel should come up evenly at all 8 ports. If not you have an internal fuel distributor problem. This will require a rebuild.

ONE MORE THING- BEFORE disconnecting the fuel injector lines go head and pull all the injectors, place them each in a shot glass and energize the system again. Have someone do this so you can check to see if the injector spray in a conical A(cone like) spray. This is necessary for proper running of these engines.
Thank you for the well detailed information; I will proceed and follow these steps. Thank you for you for your assistance.
 

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1979 450 SLC R107
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Discussion Starter · #17 ·
Check the resistance of the WUR- ohms. It should be between about 18 and 24 ohms resistance.
The WUR was rebuilt by Flowtech, but I will check the resistance, just in case.
Thank you "una vita"
 

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1980 450 SL
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The WUR was rebuilt by Flowtech, but I will check the resistance, just in case.
Thank you "una vita"
A cold start issue is not going to be the coil in the WUR or voltage to it. The coil heats a metal strip to increase the fuel pressure as the car warms up. From cold start it would be the same connected or not.
The only way to check the WUR, control pressure and inlet fuel pressure is to have a CIS Fuel pressure test setup. It's great to have this but since you just had your WUR rebuilt and it's only from a cold start, I doubt that fuel pressure is your issue. The fuel pump works best when it's cold !
 

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A cold start issue is not going to be the coil in the WUR or voltage to it. The coil heats a metal strip to increase the fuel pressure as the car warms up. From cold start it would be the same connected or not.
The only way to check the WUR, control pressure and inlet fuel pressure is to have a CIS Fuel pressure test setup. It's great to have this but since you just had your WUR rebuilt and it's only from a cold start, I doubt that fuel pressure is your issue. The fuel pump works best when it's cold !
That is exacty correct. That is the function of the WUR. I'm just telling him how to know his WUR is working correctly, how to check that and completely eliminate doubt.
Also correct about the CIS tester. It is a must have and one that was mentioned above. My advice is check-off list. Find the problem by process of elimination.

To the OP: what is your idle RPM? (Warm or cold) So long as it's not 1500rpms.

Also, do me this favor- there is a vacuum line going from the passenger side firewall right at the coolant tank and it junctions into a T. Pull it from the T and plug it. Let me know if that changes anything.
Also- you can check your idle control valve. It can be cleaned with carb cleaner. I'm sure it needs it. Then hook up 12v to it and see if the actuator closes when energized. It will pop.These can have air leaks too effectuating all kinds of problems.
 

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1979 450 SLC R107
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Discussion Starter · #20 ·
That is exacty correct. That is the function of the WUR. I'm just telling him how to know his WUR is working correctly, how to check that and completely eliminate doubt.
Also correct about the CIS tester. It is a must have and one that was mentioned above. My advice is check-off list. Find the problem by process of elimination.

To the OP: what is your idle RPM? (Warm or cold) So long as it's not 1500rpms.

Also, do me this favor- there is a vacuum line going from the passenger side firewall right at the coolant tank and it junctions into a T. Pull it from the T and plug it. Let me know if that changes anything.
Also- you can check your idle control valve. It can be cleaned with carb cleaner. I'm sure it needs it. Then hook up 12v to it and see if the actuator closes when energized. It will pop.These can have air leaks too effectuating all kinds of problems.
Thank you Unavita, I have checked the idle control valve as you indicated. I will check the vacuum lines you mentioned as well. I will keep you posted on my results/findings.
Thank you.
 
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