weird starting problem
 

I have a 1992 300D 2.5 turbo. It used to start up perfectly, but recently it has been taking me 2 trys. It always starts on the second try. The car doesn't require me to give it any gas to start it, it always fires right up on the second try. Sometimes it will start on the first. It is so reliable that if it doesn't start within a second of cranking on the first try I just turn the key back off and right back to start and it fires right up on the second try. What could be making it take 2 trys all the time?

glow plugssssssssssssss

I don't think its the glow plugs because I don't even let them warm it up the second try. If it doesn't start after first I cycle key straight back to off and then straight back to start with now warm up time and it always fires right up.

fuel filters!

Maybe the vacuum is not bleeding off the shut off valve on the first try. Pull the hose off the shut off valve manually and see if it starts on the first try.

X2
Could be the vac switch on the ignition switch is on the way out or a tube is kinked or blocked.
It would not hurt to test your GP's as well.

Quote:
Originally Posted by kerry
Maybe the vacuum is not bleeding off the shut off valve on the first try. Pull the hose off the shut off valve manually and see if it starts on the first try.
Thanks for the helpful suggestions guys, I am new to these cars so I need a little more info. Kerry: I'm assuming your talking about the fuel shut off valve? I'll try to locate that and check out the vacuum lines.
Layback 40: I'll try to check the lines for the ignition switch too. According to the previous owner the glow plugs were changed last august.

Update: Yesterday the car was parked on a steep hill with the front up hill. I couldn't get it started after multiple attempts. Yesterday was also the first day temps have been in the 80s. I figured it could be an issue with fuel not making it from the tank to engine up the steep incline or a heat issue such as an ignition switch or a starter solenoid going bad and having more resistance with the increased temps. I rolled the car to a flatter location and left windows and hood open for a few minutes to cool it down. Then I noticed how dirty the air filter was so I pulled it off. The car started. I'm figuring it can't be as simple as not getting enough air, but wouldn't that be nice? I'm about to replace the filter and then start looking into the vacuum lines. I'll let you guys know what I find out. Thanks again for the help!

Allright, sorry for being an idiot, but whats the IP? Ignition something? Intake plentum? My manual doesn't have a complete vaccum diagram and I havent been able to find an engine manual for this car yet which is where the fuel system info is I assume because its not in my regular manual.

From under the dash I see two vac lines coming in the back of the ignition, one black one black with double green stripe is one of these the one to unplug to test the shut off valve? And where is this shut off valve anyway?, I can't figure out where these lines go

IP = injection pump. it's the thing with the lines coming out of it that go to the injectors. i think on your model the shut off valve is very conveniently located right on top. there should be a vacuum line going to it. the colors you are mentioning are different than on the early 80s w123s, so someone else will have to chime in here

Sleepster: OK I know where the injection pump is and where the manual shut off valve is. So I guess it is a fuel shut off. I'm about to take a look and see what vac lines are going in there. Thanks

Looks like the shut off lever was catching on the fuel lines going into the injection pump and wasn't popping back up. Thats probably why it was always starting on the second time before. After being jarred loose the first time. I just slightly bent it out away from the injection pump and the car is starting and the vacuum is bringing the lever back up every time now. Hopefully this is the extent of my problem. Thanks a lot to all that helped!