Hard Starting SOLVED!! READ THIS!

This is a message for all those MB owners who have had a problem with hot starts. This is usually when the car sits for about a half hour after the car is shut off. The problem is a vapor lock caused by a leak in the fuel system. Many people will tell you a relay is bad or something to that effect. This is not the case. The main part to check is the fuel regulator under the air cleaner on the car. It is in the fuel system chain right after the fuel distributor. We changed almost everything else in the fuel system before we discovered that the pressure regulator was bad. We changed the fuel accumulator, pump, filters(several times), all the lines leading from the tank to the pump assembly,the injectors, and were going to try the in tank filter next. We just got lucky enough today to find a 190 that someone just gave us some parts off of.

Just remember that if the car starts fine when it is cold but has to crank for 10 or more seconds after it has been running then you should have this checked. Make sure and look at the FUEL PRESSURE REGULATOR!!!

I felt obligated to make my first post an important one. I have been reading messages about hot starting for a while but I have not heard any success stories or and solutions that proved to be correct.Well I hope this can help someone out there. Have fun with your MB's everyone. Happy motoring.

[David C Klasse]

Yes, but first try the Overvolt Protection Relay (OVP), because this is the cause of 90% of the no hot-starts. Then the fuel relay, then go further as to what you, 190Beast, suggested.

[Machnumber2]

The info very much appreciated

[stevebfl]

Actually I perfer not to try any thing. I prefer to use the proper testing and replace only what fixes the problem. I have fixed (and writen about) hundreds of cars with fuel leak down. I have fixed and writen about hundreds that wouldn't cold start because of OVP relays; and numerous other problems.

Proper direction, proper testing, equals quick results.

OVP can cause the problem, but i would like to comment to the fact of testing. I did not mind paying the costs, as i would rather find and fix the problem myself rather then go pay a ridiculous amount to have someone else find the problem. Thats just my opinion. I think its more fun that way.

Anyway the only reason I made the post was to see if it might solve a problem for someone else who wasnt finding the cause to that annoying hot start.

Thanks for the replies.

[stevebfl]

In your first post you state:

"We changed the fuel accumulator, pump, filters(several times), all the lines leading from the tank to the pump assembly,the injectors, and were going to try the in tank filter next"

I suppose that paying a trained tech (or doing the tests yourself) would be more expensive than this. In hundreds of fuel pressure leak down problems, I never charged more than two hours labor for testing. And never did I replace anything that wasn't needed. I'd say that the testing would have solved your problem for much less than the coin flip method or the "wow" it worked for me method.

I'm always glad to try and help someone do the testing themselves, but when the facilities aren't at hand, I am the first to say that you need to find a trusted craftsman.

Listen buddy the whole point was that the parts arent theat much and who cares about the cost. I feel a lot better knowing that i have the whole fuel system replaced because you dont know the history of the car. you would have to know that it sat for two years with gas in the lines. you know what happened next?

thats right. all the fuel varnished inside the entire fuel system. good guess. now my whole point was that i dont mind paying the costs cause i think it was a fun project and who cares if i enjoyed the project. the entire point of my original post was to convey the message the none of you so called "pro MB techs" had been saying. check the fuel pressure regulator as well as the stupid ovp relay. i have never heard so many people talk about the overvoltage relay as a problem. i have yet to hear of changing that solve a thing.

now that i am all riled up about this i feel it was a mistake to try and help anyone, because so many of you so called experts constantly try to discredit people. well let me tell you something you technical genuises, i figured out the problem on my own. guess what i am 16!!!!! so thanks alot.

for all the other plain folk MB owners like me, keep up the good work and dont take to heart what these "master technicians" have to say about hard starting.

thanks

[David C Klasse]

Beast,
Everyone is different. And everyone appreciates your advice as possible problem for hot starts.
The techs are just saying what they would have done. No one is discrediting you. There is no need to lash out like that. We are all very glad your problem was solved, I am sure I speak for everyone, and I thank you for posting what you did. The techs are just trying to be helpful also, remember that. They are why the site is here!

sorry about that last post guys, but sometimes i would just like to hear someone reply to my post and not get smug with me about what i should be paying to fix my mercedes the way i want to. that steve guy basically told me that i was wasting my money. well i dont think i was. i had fun working on it and i appreciate steve and everyone elses thoughts on this post.

one more time i will say this. the original post was not to start an argument or anything like that. i simply meant to let people know that my fuel pressure regulator went bad, and i never heard a word about checking that part for possible hard starting problems. i just wanted to let people know if they are diy'ers then thats a good place to check.
thanks

P.S.
you can get really cheap used parts at the site http://www.oklahomaforeign.com they are really nice people and they are prompt about shipping stuff out. great place to look for spark controllers. mercedes told me 2300 for a new one. i got one from that site for $50. worked like a charm.

[stevebfl]

You proposed a sure fire solution; which there never is. You bad mouthed my profession and seem to have no interest in "how it works". This is a technical forum. If you wish to promote "faith healing" so be it. Its never about money to me.

If you just like replacing pieces of your car, have fun. If you go back through the archives you will find numerous posts on the vapor lock condition you experienced. Your particular experience is a valuable contribution as it is not in the top two causes of that leak down condition. (They would be fuel pump check valve and accumulator)