84 300D Why can't I keep this thing running!? - Page 2 - PeachParts Mercedes-Benz Forum

kerry · #16 12-08-2016, 08:38 PM

Are you sure you aren't getting an unknown vacuum signal to the shut off valve, shutting down the IP?

caswda · #17 12-09-2016, 11:35 AM

Quote:

Originally Posted by Diesel911

The Vacuum Shutoff on the Fuel Injection Pump pulls the Fuel Rack into the shut off position. It won't work well if there is a Vacuum Leak in the system or the vacuum pump is not supplying enough vacuum.

Disconnect the hose at the Vacuum shutoff and see if there is Oil residue in it. If there is the diaphragm in the shutoof has holes and is passing oil through it. However, you can see oil and sometimes they still work normally.
As viewed from the drivers seat on the top right of the Steering Colum Lock is a vacuum shutoff valve. That could be worn out. Also the hoses on it need to go in the proper position. If you swap the positions it willnot work well.

You can have a vacuum leak anywhere in the vacuum system and it can effect the shutoff. To check the vacuum sustem you pretty much block disconnect one part of the vacuum system and plug the vacuum source and see if your vacuum situation improves. If it does the section you disconnected is the source of the leak.

For the under the hood you can visually look at and bend the rubber connectors and see if there is cracks in the rubber.

Note that the tiny plastic nipples that are on the main vacuum line snap off easily. Merely leaning on the line can break them (that happend to me during an Oil Change).

Thanks Man! Yea I want to redo that whole vac system top to bottom since these cars are so reliant on vacuum. where can I get the t's, canisters and the like, Mercedes, Hope Not! Vacuum line's easy...

caswda · #18 12-09-2016, 11:52 AM

Quote:

Originally Posted by kerry

Are you sure you aren't getting an unknown vacuum signal to the shut off valve, shutting down the IP?

I know I'm having vacuum issues because my door locks are rock solid they will not push down! What I need to get straight in my head is can the original shutdown issue be caused by the aforementioned vacuum issues? Will the engine actually shutdown do to vacuum problems? Or is it an air issue in or around the pump somwhere?? ...

kerry · #19 12-09-2016, 12:14 PM

Yes, if somehow vacuum is getting to your shut off valve, it will shut down. Something is wrong with your door locks. I would remove the brown line from the shut off valve and rely on the shut off lever under the hood for a while and see if that resolves your problem.

caswda · #20 12-09-2016, 12:38 PM

Quote:

Originally Posted by kerry

Yes, if somehow vacuum is getting to your shut off valve, it will shut down. Something is wrong with your door locks. I would remove the brown line from the shut off valve and rely on the shut off lever under the hood for a while and see if that resolves your problem.

sounds good! I will try that... Thanks!

caswda · #21 12-09-2016, 02:55 PM

Quote:

Originally Posted by kerry

Yes, if somehow vacuum is getting to your shut off valve, it will shut down. Something is wrong with your door locks. I would remove the brown line from the shut off valve and rely on the shut off lever under the hood for a while and see if that resolves your problem.

OK, Kerry, So you are a genius! Disconnected the brown vacuum line from the shut off valve, I have never been able to run that car so hard since I bought it 2 months ago... Shifts and downshifts beautifully and is not shutting down till I hit that lever!... lol Thank you!

Oh while running drivers door lock locks fine, other three doors hard and spongy. So I guess the question is now? Where exactly does that leave me?

kerry · #22 12-09-2016, 03:05 PM

Ok, I'll accept that designation and request that the moderators replaced 'Registered User' with 'Genuis' under my name.

Diesel911 · #23 12-10-2016, 12:35 PM

Quote:

Originally Posted by caswda

I know I'm having vacuum issues because my door locks are rock solid they will not push down! What I need to get straight in my head is can the original shutdown issue be caused by the aforementioned vacuum issues? Will the engine actually shutdown do to vacuum problems? Or is it an air issue in or around the pump somwhere?? ...

Added: I had not read Kerry's post when I posted the below info.

That is easy to trouble shoot. Disconnect the Vacuum Line at the Vacuum Shutoff on the Fuel Injection Pump and plug the vacuum line end you disconnected.
If you can start and drive with out the problem showing up
then it is likely you have some vacuum issue.

Altenativly you can disconnect that Vacuum Hose at the Vacuum Shutoff and connect a Vacuum Gauge to it. Start the Engine. You should be getting no vacuum reading.

High crankcase/blow by pressure can push the Vacuum Shutoff towards the shut off position. Make sure the vent on the valve cover and the related tubing are not obstructed.
You can start your Engine and remove the Oil Fill Cap and see how much blow by chufs out.

kerry · #24 12-10-2016, 01:45 PM

If it runs fine with the brown line removed it is highly unlikely that it is internal crankcase pressure activating the shut off valve. It is likely an errant vacuum signal in the brown line.

caswda · #25 12-10-2016, 02:41 PM

Disturbing Update!
It acted up with the same symptoms today only it took longer to start acting up!
Sorry kerry!, I thought you were a genius...

caswda · #26 12-10-2016, 02:45 PM

Quote:

Originally Posted by Diesel911

Added: I had not read Kerry's post when I posted the below info.

That is easy to trouble shoot. Disconnect the Vacuum Line at the Vacuum Shutoff on the Fuel Injection Pump and plug the vacuum line end you disconnected.
If you can start and drive with out the problem showing up
then it is likely you have some vacuum issue.

Altenativly you can disconnect that Vacuum Hose at the Vacuum Shutoff and connect a Vacuum Gauge to it. Start the Engine. You should be getting no vacuum reading.

High crankcase/blow by pressure can push the Vacuum Shutoff towards the shut off position. Make sure the vent on the valve cover and the related tubing are not obstructed.
You can start your Engine and remove the Oil Fill Cap and see how much blow by chufs out.

Thanks bud... Back to square one... I guess I'll keep plugging away at the vacuum since that seems to be at least part of the cause...

caswda · #27 12-10-2016, 02:48 PM

Quote:

Originally Posted by kerry

If it runs fine with the brown line removed it is highly unlikely that it is internal crankcase pressure activating the shut off valve. It is likely an errant vacuum signal in the brown line.

This time before loss of power the engine would start to miss or make like a jumping movement...

What are your thoughts on a bad injector.. seems to happen after she's hot! and she is smoking a little bit more than I remember but its not really a dark black smoke...

kerry · #28 12-10-2016, 03:03 PM

A bad injector won't shut the engine down. Try driving it with the oil fill cap off to relieve any crankcase pressure.

caswda · #29 12-10-2016, 04:41 PM

Quote:

Originally Posted by kerry

A bad injector won't shut the engine down. Try driving it with the oil fill cap off to relieve any crankcase pressure.

Did that.. No change just a big mess...

I'm stumped! I can make it bog down if I lay into it that's when it really starts to get bad I would still go for fuel supply but I've had that auxiliary tank hooked up and there was definitely no air getting to it then and I had the same issues. I just don't know these cars are crazy....