The Mystery Deepens

Welcome to the continuing saga of a rough running gasoline smelling C280, which in the past week, has received the following:
New plugs, new wires, new end caps, new boots and, finally tonight, a new OVP relay. And, after all this - guess what?

IT STILL RUNS ROUGH AND REEKS OF GASOLINE

Still no "Check Engine Light" but, after replacing the OVP, the ABS light goes out like it should.

Could the problem be vacuum related? O2 sensor? Or am I looking at the dreaded "Wiring Harness" problem.

Please, any suggestions at this point will be greatly appreciated.

I'm sure as heck out of ideas.

Thanks!

[JimSmith]

americanrm,

The statement the car reeks of gasoline sounds like a fuel leak. Check the thread "Hot Start Problem Solved" on this board where a fuel stink, and some hot starting problems were cured and improved respectively by replacing a fuel distributor O-ring. Good luck, Jim

Jim:

Thanks for that advice. I will check it out in the morning. However, the car exhibits absolutely no hesitation in starting. It's just that, when it does fire up (immediately) it runs like an old John Deere tractor - rough.

Also, when I give it gas, it hesitates and you can hear a swishing sound like a laboring engine, trying to digest the fuel coming in. You know the sound - same sound an old afb four barrell carb used to make when out of adjustment and flooding.

Thanks again for the tip. I'll check it out. ANy other ideas?

Bob

[yal]

Its most likely fuel related. Everything you changed above has to do with spark. Fuel distributer is a good place to start, also check your regulator and see if your injectors are leaking. Have you done a fuel pressure check yet?

[Richard Eldridge]

A friend of mine once had a problem with a 1957 Oldsmobile. The fuel line had somehow gotten a tiny hole in it (aparently not a severe or noticeable leak) and was sucking air. This was discovered by hooking a compressor to the line and pumping air through it. It made a whistling sound and was discovered that way. The problem was discovered on the car's fifth trip to the shop.

Could this happen on a Mercedes? I am assuming that fuel lines are made of better stuff on a MB, and they are much beter positioned. This Olds had the line running down the frame rail, easily exposed to the elements.

Just a thought.

[RPM55]

Its very possible that the fuel pressure regulator is bad and leaking fuel into the intake manifold through the vacuum line connected to the regulator.The pressure regulator is located on the front end of the fuel rail. Try pulling the vacuum line off of the regulator to see if there is gas in the line.

Yal:

Thanks for those tips. Now, if I can figure out where to find the distributor and regulator, I'll be on a roll.

In the meantime, do you think the problem could be vacuum related? I ask this because of something I noticed this morning.
Normally, the brakes on this car (new 3 mos ago) are very firm and responsive. Today however, they felt mushy and very unresponsive.

Could this indicate a vacuum leak? And, could such a leak (if there is one) be causing or contributing to the problems?

Anybody else ever have a similar problem?

Originally posted by RPM55
Its very possible that the fuel pressure regulator is bad and leaking fuel into the intake manifold through the vacuum line connected to the regulator.The pressure regulator is located on the front end of the fuel rail. Try pulling the vacuum line off of the regulator to see if there is gas in the line.

Thanks. I'll try it as soon as I can be sure I'm looking at the right thing. With your instructions, I think I can find it.

Bob