1984 Mercedes 380SL R107 Checking cold start valve and fuel pressure regulator

[@dosullivan6594]

Great looking SL. I wish I had your mechanical mindset. Good work.

[@sophiathe380sl]

Haha. Thanks. Lots of youtube research 😂

[@tonyreyes9969]

As far as I know that is not a fuel pressure regulator, its called a fuel damper and its function is to deaden the noise of the fuel flow. On a K-Jetronic fuel injection system, the primary pressure regulator is incorporated in the fuel- distributor housing, it maintains the primary pressure at about 5 bar. Due to the fact that the electric fuel pump delivers more fuel than the engine needs, a plunger shifts in the pressure regulator and opens a port through which excess fuel can return to the fuel tank.

[@sophiathe380sl]

Thanks for the comment. You’d know more than I do. 😀

[@excelerater]

So I am having an issue. Can't figure out fuel pump is buzzing and acting like it's starved. Added a new pump and some fuel and car ran great and went for a ride. A few days later problem came back. Pump is buzzing and car is acting like it's out of fuel .

[@sophiathe380sl]

The pump buzzing is kinda normal but depends on how loud it is. You may need a mechanic to hook up some fuel pressure gauges to identify the issue. Report back.

[@excelerater]

@@sophiathe380sl Fuel tank is not venting..Took off gas cap and all is normal..Not sure if its the cap or something in the lines

[@sophiathe380sl]

@@excelerater ahhhh. You’re the guy that posted on Facebook. 😄

[@excelerater]

@@sophiathe380slyes sir. the green 450 that's me. I checked all my vent lines. It's either the purge valve or the gas cap so I ordered both. Car runs perfect without the gas cap .

[@excelerater]

@@sophiathe380sl added a new pump,ran good for a day then did the same thing again..I have hoses,filter and accumulator on the way

[@touiederosas2013]

What brand did you use as a replacement for your Fuel Accumulator?

[@sophiathe380sl]

I believe it was Bosch. I made a video on the replacement with the pump and filter.

[@touiederosas2013]

@@sophiathe380sl Gotcha. Good thing I didnt order the URO part and found a brand new Bosch part online, waiting for it to arrive to sort my hot start/fuel starvation issue.

[@sophiathe380sl]

@@touiederosas2013 good luck! Not sure if you’ve been following along but first it was my accumulator. 6 months later it was a part on the back of the fuel distributor. All good now.

[@touiederosas2013]

Yes! Ive been following :) did that one already, accumulator not yet. Opposite of what you did haha. Cant wait for my accumulator!

[@inovahightechltd]

Have you checked / tested your warmup regulator?

[@sophiathe380sl]

Just got back from the mechanic. It was a regulator holding a plunger behind the distributor. I’ll do more research and make a video. $500, fixed it.

[@arlingtonrva1780]

@@sophiathe380sl I will be eager to see that video. A plunger behind the distributor? Your videos are really helpful. Like you, I have limited experience and am not a mechanic. I am trying to give it a go myself based on online posts and videos. My 83 380SL also seems to have a lot of the same issues that your 107 does.

[@sophiathe380sl]

@@arlingtonrva1780 that’s awesome to hear. I’m glad my non-mechanic videos are helpful 😂

[@mercedeske]

As for the cold start valve - on your car it has to be working up to about 60 degrees F. You should have hooked up the pressure gauge to see if you have pressure loss or not.

[@travisedson4101]

@@sophiathe380sl Having the same issues here. Fuel distributer was changed in mine so I'm wondering how often these regulators go bad...

[@grantbellinger7403]

Beautiful matey,thank you for videos cobba,much appreciated!

[@louisgualtieri4960]

Did you get it sorted out I have exactly the same issues on my 380sl done exactly what you have done except taking to a mechanic.

[@sophiathe380sl]

Yes. I had to take it to a mechanic to get it fixed. I made a follow up video that shows the part that was changed.

[@nickyborrisino]

Your air plate is too tight. It should have minimal play(2-3mm) when system is pressurized. Because of this, your fuel distributor is circulating fuel with just key on and pumps priming which floods your engine. Crack an injector line with key in on position and pumps priming, you should not get fuel flow from the top of the fuel distributor until you depress plate. This is what which gives you hard starts with engine at normal operating temperatures. You have to keep in mind that your fuel system was the last most updated iteration of mechanical fuel injection systems. Even though it is old, it was state of the art in its day and it needs to be rebuilt and calibrated every once in a while to keep it running at acceptable parameters.

[@sophiathe380sl]

Thanks Nicky. I got this issue resolved in another video down the line. It was some piece that goes behind the fuel distributor. Unfortunately, the mechanic did it.

[@nickyborrisino]

@@sophiathe380sl Electro Hydraulic Actuator valve….

[@sophiathe380sl]

@@nickyborrisino sure..😂😂… it had a few shims. I guess that’s the one. Anyway, 500 bucks later, car is perfect again.

[@nickyborrisino]

@@sophiathe380sl still keep in mind as the system ages, the plate height and free play will need to be adjusted eventually along with mixture screw.

[@sophiathe380sl]

@@nickyborrisino thanks for the info. May be more than I can do. Also, I don’t have any of the fuel gauges.

[@albertmagnusson9098]

Hey man, we just got a 1984 380sl last year and "Cold start fuel injector" is not functioning. Anyone know where to get a replacemwnt unit?

[@sophiathe380sl]

Hey. Apparently, in my climate, I was told mine will never fire. You should look that up. Unless, it’s really cold, it may never activate. Double check with a mechanic before replacing it.

[@albertmagnusson9098]

Yes, we have cold weather here in Iceland. The mechanic has confirmed this is the part needed but we are just looking for the part itself, any suggestions?

[@sophiathe380sl]

@@albertmagnusson9098 Iceland seems cold enough. 😂 probably not a lot of junk yards with r107s there. Probably eBay is your best source

[@TanveerAhmed-gl5jk]

Crap engineering