1985 380 Sl Starting Problem - PeachParts Mercedes-Benz Forum

samonline · #1 06-26-2009, 06:25 PM

Hello;

I put a new battery ,new fuel pump, new fuel filter, new accumulator , new spark plugs, new Fuel distributor and fresh oil and fresh fuel, I have checked all fuses and relays and ovp all running good. The car start for 1 or two seconds than dies again. I put some fuel in the jar in front of the FD, the car start again til the fuel is gone.

What I am doing wrong , can somebody help me please. Thanks Sam

jplinville · #2 06-27-2009, 08:42 AM

Quote:

Originally Posted by samonline

Hello;

I put a new battery ,new fuel pump, new fuel filter, new accumulator , new spark plugs, new Fuel distributor and fresh oil and fresh fuel, I have checked all fuses and relays and ovp all running good. The car start for 1 or two seconds than dies again. I put some fuel in the jar in front of the FD, the car start again til the fuel is gone.

What I am doing wrong , can somebody help me please. Thanks Sam

do you have proper fuel pressure leading to the injectors?

samonline · #3 06-27-2009, 10:26 AM

I have noticed that the "air idle control valve " is getting 4 volts instead of 12 volts when ignition is on . Is that normal also the "frequent fuel valve " located on the side of the FD is getting only 7 volts instead of 12 volts . I guess I have electrical problem, what I should check .

For the Fuel pressure , what is the measurements of pressure that I need and what should I check first with the pressure machine . And is the pressure machine is available at any auto place or I have to order it . Thanks Sam

blueshield11 · #4 06-28-2009, 11:26 AM

Quote:

Originally Posted by samonline

I put some fuel in the jar in front of the FD, the car start again til the fuel is gone.

Are you sure your new fuel pump is placed correctly? When you turn the ignition you should hear it working.

ctaylor738 · #5 06-28-2009, 01:53 PM

Sounds to me like your fuel pump may be running only when the starter is cranking and then shutting off when you release the key, OR that you get a puff from the cold start valve and nothing from the injectors.

Try removing the fuel pump relay. Look at the pins and then jumper 30 to 87 in the socket and see if the car will run. If it does, this would indicate a relay or wiring problem.

samonline · #6 06-28-2009, 04:09 PM

I did run the test and bridge 30 and 87 , I heard the fuel pump running , But car still did not run , I removed one injector to see if it spray , but it does not , what should I do from this point . Should I go ahead and order a new relay or I can test it again somehow . And do you thinks that the voltage that I have mentionned before makes any differences? Thanks

ctaylor738 · #7 06-28-2009, 07:09 PM

The readings for the idle control valve and the frequency valve are fine.

Leave the relay alone, it is probably OK since jumping the contacts didn't change anything.

Try this.

Remove the air cleaner. Bridge the relay so the pump runs. Press down on the air sensor plate and see if it moves down easily and returns quickly to the upward position. If it doesn't then you may have a sticking piston in the FD or some other problem that will need to be addressed.

If that's OK, keep the relay bridged and have someone crank the starter while you press the air sensor plate down a half inch or so with a stick (because you may get a backfire). If you can keep the engine running by doing this, the next thing I would do is to adjust the mixture VERY CAREFULLY to make it richer. Use a long-arm 3mm hex key and turn it clockwise (right) 1/8 of a turn at a time, try a start, do it again, etc., being very careful to keep track of how far you have gone. Do not go more than a full turn.

If this doesn't work, you probably don't have enough fuel pressure to open the injectors and you will need to figure out why. The first step would be to check system and control pressure - lots of posts on how to do that.

samonline · #8 06-28-2009, 08:51 PM

I have noticed that the Fuel frequency valve is leaking gas, I am going to stop here til I receive the new one and continue the rest of the tests later. thank you chuck . I 'll get back with you later next week.

samonline · #9 07-08-2009, 12:09 AM

System and control pressure is my next step , after I have tried to bridge 30 and 87 on the relay, and try to start the car but stil car does not start.Any particular post I can go to help me solving this problem.

ctaylor738 · #10 07-08-2009, 07:50 AM

Does the pump run when you bridge the relay? Sorry, I had to ask.

Did you try the things I suggested in my earlier post?

samonline · #11 07-08-2009, 07:54 PM

Yes the pump run when I bridge the 30 and 87. I did try what you suggest earlier Chuck , the car still does not start and no fuel spray from injectors.

ctaylor738 · #12 07-08-2009, 09:41 PM

Bridge the relay so the pump runs. Loosen a couple of the injector fittings on the top of the FD and see if you are getting gas there. Push the air sensor plate down a bit and see if that makes the gas flow.

samonline · #13 07-09-2009, 10:03 AM

I did Chuck , and the gas flow perfectly from all of them, one by one it flow even more when I press on the plate. I am waiting for the next step please. Thanks again .

ctaylor738 · #14 07-10-2009, 09:40 AM

You are sure that you are getting spark? The plugs are dry?

If this is the case then you need to check system and control pressure. You do this by putting a gauge between the warm-up regulator and the fuel distributor.

About the only possibility left is that you are not getting enough pressure to open the injectors.

This is very puzzling.

samonline · #15 07-10-2009, 11:44 PM

Chuck you are right, I pulled a spark plug and it is burned but dry no smell of gas. I am going to look for a metric pressure machine and go from there . what are the pressure in psi suppose to be . Thanks Sam