How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Marty Your Own Question
Marty, Mercedes Technician
Category: Mercedes
Satisfied Customers: 54018
Experience:  Bosch Certified Master Tech. Over 35 years experience.
Type Your Mercedes Question Here...
Marty is online now
A new question is answered every 9 seconds

450 SL: I have a 1978 Mercedes Benz SL the fuel pump has been

Customer Question

I have a 1978 Mercedes Benz SL the fuel pump has been replaced and the fuel is getting to the carburetor as long as we poured gasoline into the air filter area it will run for a few seconds then it just cut off no matter how many times we try we bled all the lines it still will not stay started any suggestions
Submitted: 2 years ago.
Category: Mercedes
Expert:  Marty replied 2 years ago.
Hi, welcome to Just Answer. My name is***** you give me some background? Has this car been sitting for a long time? Are you a mechanic?
Customer: replied 2 years ago.
Yes Marty the car with seating for approximately five years in North Carolina in a yard we cleaned out the fuel tank and all the lines redid the spark plug wires made sure they were set to the right numbers put a new fuel tank fuel filter on sorry fuel pump on no I am NOT a mechanic my husband has been a mechanic for several years but he's never worked on a Mercedes so we're lost we can get it to start but it will not stay started no matter what we do
Expert:  Marty replied 2 years ago.
Ok, assuming that the work done on the fuel tank and the pump is good and that there is fuel getting all the way to the fuel distributor the problem will be a faulty control pressure regulator and a faulty fuel distributor. I restore a lot of SL's that have sat for a long time. Anytime they sit the fuel distributor and the control pressure regulator will inevitably need to be replaced. The fuel distributor is the part in the middle with all of the fuel lines coming out of it. The control pressure regulator is the part at the front of the intake manifold with two fuel lines and an electrical plug. Fuel comes from the tank and into the fuel distributor where it goes through a pressure regulator and some orifices and leaves out the top of the fuel distributor and into the control pressure regulator where the pressure is reduced and eventually returns to the tank. Both of these items tend to plug up from the old fuel sitting in them for so long. Cleaning them usually does not work. If your husband wanted to try something he could remove the fuel distributor and turn it upside down and check the plunger in the bottom of the fuel distributor. The plunger will most likely be stuck. He can try freeing it up and getting it moving in the bore again then reinstall it and see if it will work. He must be very careful not to damage the plunger or the bore that it slides in as it is a very precise fit. He also must NOT disassemble the two halves of the fuel distributor. If he has no success he will need to locate a used fuel distributor and control pressure regulator on ebay. I've had better success with used parts over the so called "rebuilt" parts. The control pressure regulator is commonly referred to as the warm up regulator.
Let me know if you have any questions. Please be sure to rate my service if this is helpful.
Customer: replied 2 years ago.
Okay Marty we're going to try that tomorrow morning because it's dark here and we been working on this car all day it sounds very reasonable and something we were looking at but didn't really understand how it worked so we will let you know if that's what the issue is thank you
Expert:  Marty replied 2 years ago.
You're quite welcome. I'll be here if you need anything. Please remember to rate my service in order for the website to credit me for my help. Rating my service does not close the question. You can still reply back if you need further assistance.
Expert:  Marty replied 2 years ago.
Hi, I'm just following up with you on the Mercedes. Was my answer helpful? Please let me know.