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Marty
Marty, Mercedes Technician
Category: Mercedes
Satisfied Customers: 53945
Experience:  Bosch Certified Master Tech. Over 35 years experience.
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I have a 1985 mercedes 380 se.. that will only start when u

Customer Question

hi!i have a 1985 mercedes 380 se.. that will only start when u hold the flapper down some with a screwdriver
JA: Will the headlights turn on? Is the battery fully charged?
Customer: yes
JA: What is the model of your '85 Mercedes?
Customer: 380se
JA: Are you fixing your 380SE yourself? What have you tried so far?
Customer: changed engine due to old one bending a valve...inew one will start if u hold the flap open some
JA: Anything else you want the mechanic to know before I connect you?
Customer: need to no what makes the flap open..if it is vacumm or done by fuel pressure
Submitted: 11 months ago.
Category: Mercedes
Expert:  Lou P. master tech replied 11 months ago.

Hello, my name is***** and i will do my best to assist you.I am going over your story now and will reply back soon with some info,thanks!

Expert:  Lou P. master tech replied 11 months ago.

did you swap over any parts from the old engine to the newer engine?

also fyi the airflow plate is opened strictly by airflow and levers against a pintle in the bottom of the fuel distributor (spider looking unit) so please do not press against it or you can damage the lever or fuel distributor.

Customer: replied 11 months ago.
used the whole fuel distributor of old motor..it ran fine,but put it on new motor and didnt run
Customer: replied 11 months ago.
is there any testing i can do? to see what is the cause of the problem
Customer: replied 11 months ago.
only thing i didnt change was the injector seals..plastic!
Expert:  Lou P. master tech replied 11 months ago.

Yeah plastic on the old cars is never good. So it's possible you have a huge vacuum leak and the reason the car runs when pressing the plate down is because you are actually forcing more fuel pressure and quantity out of the injectors.

Customer: replied 11 months ago.
the plate flutters for a few seconds and that is it..it will not flutter until it sits for a bit...all vaccum lines are good ect..so i should install new injector seals?to solve the problem
Customer: replied 11 months ago.
i just put new boots on throttle body to the fuel distributor
Customer: replied 11 months ago.
It's just puzzling...seeing that it worked fine on old engine...I even put clamps on things just to ensure there is no vacuum leaks
Customer: replied 11 months ago.
Had it apart half a dozen times..trying to find a problem..I am a certified mechanic ..I have access to tools
Expert:  Lou P. master tech replied 11 months ago.

i am here looking over the info, these systems are not that easy to diagnose especially since you had it working on the old engine and not the new.

let me opt out to see if another expert can help, i know there is an expert that has dealt with these many times. hopefully he will jump in.

Expert:  Marty replied 11 months ago.

Hi, my name is***** you keep the car running by manipulating the air flow sensor plate? It would be a lot easier if I called you.

Customer: replied 11 months ago.
it does..revs up and down when you play with it..let it go and car stalls
Expert:  Marty replied 11 months ago.

Do you want me to call you? You will need to accept the phone offer if you do.

Customer: replied 11 months ago.
No thx..if u can point me in right direction,would b cool
Expert:  Marty replied 11 months ago.

Can you get it to idle by manipulating the plate?

Customer: replied 11 months ago.
only if u hold it open a little
Customer: replied 11 months ago.
other than that it will not start
Expert:  Marty replied 11 months ago.

Okay, it sounds like you have an intake leak or a fuel pressure problem. First I would smoke test the intake for vacuum leaks. Next I would run a fuel pressure test. If you have no leaks and the fuel pressure is correct I would adjust the fuel mixture.

Customer: replied 11 months ago.
it has new gaskets ect.all torqued to spec.with it running i sprayed some brake clean everywere and nothing changes
Expert:  Marty replied 11 months ago.

Then I'd adjust the mixture.

Customer: replied 11 months ago.
that would make the plate move?
Expert:  Marty replied 11 months ago.

You're not trying to move the plate by adjusting the mixture you are changing the relationship of the plunger in the fuel distributor to the plate. When you push down on the plate you are adding fuel. You should make sure the fuel pressure is good. You should also make sure that the overvoltage protection relay is good and that the fuses in the relay are not blown.

Customer: replied 11 months ago.
already checked fuses..was hoping for a easy fix..lol..which way would i turn the screw?and were is it located
Expert:  Marty replied 11 months ago.

There is one are two fuses in the OVP relay that power the EHA valve on the side of the fuel distributor. The relay is located at the back of the engine compartment. Turn the mixture screw very slightly in the clockwise direction in order to richen the mixture. The mixture tower is between the air flow sensor plate and the fuel distributor. You need a 3mm Allen. Press down on the spring loaded adjuster with the Allen to engage the mixture screw below.

Expert:  Marty replied 11 months ago.

Just checking in. Do you need anymore help with this?