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Discussion Starter #1
this is 1984 300td
i had to change ignition switch due to glow plug light giving me hard time after achange it now ihave this problem the car start for 3 seconds and shut off and then if i unplug one the vacum hose next to the switch the car start but it will not a shut off from the key what could be the problem thanks
 

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How is it connected under the hood?

If it's tied in after the Locking system one way valve, your shut off valve will continually have vacuum, resulting in shut down. The only time the shut off valve shoud recieve vacuum, is when you are shutting the car down, Get a mity vac and start testing.
 

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Discussion Starter #5
rrgrassi said:
How is it connected under the hood?

If it's tied in after the Locking system one way valve, your shut off valve will continually have vacuum, resulting in shut down. The only time the shut off valve shoud recieve vacuum, is when you are shutting the car down, Get a mity vac and start testing.
IS IT EASY TO DO .WHERE CAN I FIND MITY VAC?
 

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What is your location?

You can get a mity vac for $30-$40 at AutoZone or O'Reilly's

It is easy to do.

Under the hood, it is the brown line that feeds the fuel shut off valve. You can disconnect that from the vacuum connector, usually a rubber 3 or 4 way connector, but plug where you disconnected it. Start and try to shut down the car. If it still shuts down, the fuel shut off valve is suspect. If it does not shut down, use the mity vac to creat vacuum to shut it down, or use the "STOP" lever.

The fuel shut off valve should not get anny vacuum while the ignition switch is in the run or start position. The ignition switch acts as a block when it is in the run or start position. Any other position, and the ignition switch allows vacuum to get to the fuel shut off valve.
 

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Discussion Starter #7
rrgrassi said:
What is your location?

You can get a mity vac for $30-$40 at AutoZone or O'Reilly's

It is easy to do.

Under the hood, it is the brown line that feeds the fuel shut off valve. You can disconnect that from the vacuum connector, usually a rubber 3 or 4 way connector, but plug where you disconnected it. Start and try to shut down the car. If it still shuts down, the fuel shut off valve is suspect. If it does not shut down, use the mity vac to creat vacuum to shut it down, or use the "STOP" lever.

The fuel shut off valve should not get anny vacuum while the ignition switch is in the run or start position. The ignition switch acts as a block when it is in the run or start position. Any other position, and the ignition switch allows vacuum to get to the fuel shut off valve.[/QUote
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i`m from CT we do have AutoZone so tomorrow i`m gonna give it try.thanks
 

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Discussion Starter #8
I fixed it I started all over from scratch and I make sure ignition switch is on position 1 using flat screw driver than i attached it to the lock .Now my Benz is working great again .thanks to everyone.
 

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rrgrassi said:
Under the hood, it is the brown line that feeds the fuel shut off valve. You can disconnect that from the vacuum connector, usually a rubber 3 or 4 way connector, but plug where you disconnected it. Start and try to shut down the car. If it still shuts down, the fuel shut off valve is suspect. If it does not shut down, use the mity vac to creat vacuum to shut it down, or use the "STOP" lever.

So, you want him to disconnect the line to the ignition shut-off at the key (which then leads to the IP valve)?
How could the car still shut off without vacuum to the shut-off circuit?
I don't get it.
 
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