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  #1  
Old 06-21-2022, 12:55 PM
E300d 1995
 
Join Date: Jun 2017
Location: Near Lake Texoma
Posts: 395
95 E300D Questions about how vacuum relates to start of engine

On my 95 E300D, 135,000 miles. It's suddenly become consistently hard to start the first time of the day. Takes about 4 tries of fairly long cranking. Then it starts easily the rest of the day.

I've tried parking it pointed downhill on a pretty good slope with a full fuel tank and it is still hard to start in the morning.

I think the most common reason is the fuel drains back and the air has to be pumped out of the lines. But I've tried to eliminate that by using viton o-rings and replacing clear plastic lines with high quality Gates fuel lines and small fuel hose clamps.

When the problem occurred it was immediate. All previous days it would start immediately.

I do not know how the vacuum relates to the fuel shutoff valve.

Does the 95 have a vacuum reservoir or does it need the engine turning to build a vacuum?

Does the ignition switch vacuum valve block the vacuum to the shutoff valve?

Should the vacuum system hold vacuum overnight or does it need to crank to build vacuum?

If I connect a vacuum gauge what should it show before trying to start, while starting, and after shutoff?

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  #2  
Old 06-21-2022, 01:07 PM
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Join Date: Oct 2012
Posts: 5,919
Just remove the vacuum line from the shutoff. First thing before you start it in the morning. Starts right up you know the problem is in that circuit.
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  #3  
Old 06-21-2022, 02:22 PM
E300d 1995
 
Join Date: Jun 2017
Location: Near Lake Texoma
Posts: 395
Thanks much ,
I'll look for a way to remove it without pulling the intake manifold.

Guess that means the ignition switch vacuum portion applies vacuum to energize the shutoff?

If so, that should mean it doesn't have to have/build vacuum to start and run?
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  #4  
Old 06-21-2022, 08:55 PM
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Join Date: Oct 2012
Posts: 5,919
Yes, vacuum shuts it off.
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  #5  
Old 06-21-2022, 09:08 PM
Diesel911's Avatar
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Join Date: Sep 2007
Location: Long Beach,CA
Posts: 44,471
Out of curiosity you did not mention if you are using your glow plugs or if you checked them to see if they were working.

Also, people have rebuilt or purchased a new fuel supply lift pump.

A more bizarre issue is crankcase pressure can build up on the opposite side of the Vacuum Shutoff on the fuel injection pump and push it in the shut off direction. If you remove the oil fill cap and it reliably stats faster, it could be something causing the crankcase pressure, or your crankcase breather system is restricted.

Is your EGR on when it is not supposed to be?
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  #6  
Old 06-22-2022, 12:48 PM
E300d 1995
 
Join Date: Jun 2017
Location: Near Lake Texoma
Posts: 395
Thanks for the replies,

I've a lot of delayed preventative maintenance issues including a new lift pump. That might be it. Parts are purchased but we've been snowed under trying to help younger relatives with their kids and issues while they suffer through a home remodeling project.

The EGR is blocked with thin aluminum from a soft drink can.

Guess I'll have to start the maintenance tasks sooner than hoped. I plan to replace the glow plugs, injectors, water pump, thermostat, alternator bearings and brushes, fan clutch, fan, most hoses, fuel pump, belt tensioner pulley, and a few other things. Probably start with the ' starting ' related items first, I don't want to burn out the starter.
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  #7  
Old 06-28-2022, 09:58 AM
E300d 1995
 
Join Date: Jun 2017
Location: Near Lake Texoma
Posts: 395
Read a few more comments posted on the internet about hard start issues for the 606 engine.

Read a couple that discussed failure of the glow plug circuit to turn on any glow plugs.

Decided to plug in my block heater. After a couple of hours heating the block, the engine fired off immediately. So guessing that is where the hard start problem is.

I did notice another clue mentioned by some of the posts that pointed to a problem with the glow plugs and not a fuel related issue.

During the latter long cranking periods while trying to start the car, there was unburnt fuel vapor/smoke coming out of the exhaust. When it did start there was a big burst of smoke that cleared immediately.

I'm surprised the engine wouldn't immediately fire off on the hot 100 degree days without glow plugs working.

Will be using the block heater til I have time to work on the glow plug issue.
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  #8  
Old 06-30-2022, 02:32 PM
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Join Date: Oct 2012
Posts: 5,919
Your description indicates to me that the engine does possibly have some wear. Not unusual with really old cars. Does not indicate it is on it's deathbed.

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