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  #1  
Old 10-10-2001, 10:37 PM
scuba
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Vacuum diagram

I have a 1980 model 450SL and wonder if anybody has a vacuum line diagram.
My vehicle does no have a catalytic converter anymore since the person I bought it from must have taking it out.
The engine gets fuel and the plugs spark to, but my car won't start.
I like to see if the vacuum lines are hooked up correctly.

Thank you very much

Gunter

I need some help please.
My car still wont start, just installed new spark plugs, new coil, new cable between the ignition modul and distributor.
I aslo checked the cylinder compression and have between 11 and 12.5 Kg/cm2, but I noticed that a lot of gas mist came out of the cylinders when I checked the compression.
Is it possible that my injection system just dumps to much fuel into the cylinders ? The spark plugs are creating a good spark, but the car just wont start.
Any help would be appreciated

Gunter


Last edited by scuba; 10-22-2001 at 05:30 PM.
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  #2  
Old 10-11-2001, 03:22 PM
sixto's Avatar
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I believe the Chilton manual has vacuum diagrams for US cars. Email me directly (there's an email button below this post) if you don't get a better offer.

I doubt that vacuum lines are the problem with your car. It might be difficult to start or keep idling, but it will start even with all the vacuum lines disconnected.

Sixto
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  #3  
Old 10-11-2001, 06:22 PM
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Make sure you have fuel pressure while turning over the engine and you have spark into the cylinders.
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  #4  
Old 10-14-2001, 08:21 PM
scuba
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Quote:
Originally posted by Benzmac
Make sure you have fuel pressure while turning over the engine and you have spark into the cylinders.
Thank you very much Benzmac,

I'm sorry that I just get back with you today, but I just returned from a trip to Augusta, Ga.
I must have enough fuel pressure, because my sparkplugs are soaked with fuel after I try to start the car.
I have a spark on the plugs, but I have to check on Tuesday if the spark is strong enough to ignite the fuel.
I still like to find a diagram or photograph from a 1980 model 450SL, just to see if my vacuum hoses are hooked up correctly.

Thanks again for your help and good luck with your shop.

Gunter
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  #5  
Old 10-15-2001, 12:14 AM
sixto's Avatar
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Have you checked ignition timing? Spark + fuel should be enough IF the spark comes at the right time. Did you just replace the plug wires? Did you remove the distributor?

Sixto
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  #6  
Old 10-15-2001, 01:41 AM
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If you just replaced wires, did you put them back in the correct firing order?
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  #7  
Old 10-22-2001, 05:34 PM
scuba
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Help please

Thank you
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  #8  
Old 10-26-2001, 11:54 AM
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I had a simalar problem on my 88 190E. The shop ran test and found it to be the cold start valve. It would pump too much fuel and flood it out. Replaced the valve and car runs now. This helped mine and may help yours. There are many things that can go wrong , this is only one.
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  #9  
Old 10-26-2001, 04:13 PM
MIKE FREEMAN
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FIRST THINGS FIRST,MAKE SURE YOU HAVE GASOLINE IN THE TANK AND NOT DIESEL OR WATER.
IF FUEL IS OK CHECK THE AIR FLOW METER(THE LARGE ALUMINUM DISC UNDER THE AIR CLEANER)IT SHOULD BE NICELY FITTED IN THE BORE BUT NOT TOUCHING OR STUCK.
THE AIR FLOW METER SHOULD OFFER SOME RESISTANCE WHEN BEING DEPRESSED AND SHOULD RETURN TO THE TOP WHEN RELEASED.
MF
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  #10  
Old 10-26-2001, 09:03 PM
scuba
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vacuum

Thank you for your help guys, I think I narrowed the problem down to the fuel distributor. I checked the fuel pressure today and it was at 65 PSI, which is right on the money. But then when I turn the ignition off the pressure drops in half a second to zero. When I take the spark plugs out and start the engine, a fuel - air mix is just gashing out of the cylinders. So I think my fuel distributor is missed up, even though its brand new.
Does anybody have any ideas what it could be ?
Thanks again for your help.

Gunter
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  #11  
Old 10-27-2001, 11:37 AM
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If your distributor is new, it sounds like you are massively out of adjustment.

The fact that your system pressure drops to zero is also a problem DEPENDING where you are measuring it at. This problem is NOT the one keeping you from starting.

First you should check to see if the piston doesn't bind as you push down on the airvalve with the engine off, but the fuel pump running (remove relay and jump circuit for testing).

While doing this you will be pouring fuel out of the injectors so do it quickly. Next you should set the base setting for new installation of fuel distributor. To do this remove a few injection lines from the distributor (maybe all of them - to get a better view). Next by-pass momentarily the fuel pump. If fuel comes from the distributor, turn the adjusting screw counterclockwise until fuel no longer comes from the output ports. Then turn clockwise until fuel starts rising again (use a cloth to absorb the fuel so that you can see it raise in the threaded port). Now again turn the adjuster counter clockwise till the fuel just stops flowing.

Now press down the airflap and view the flow. It should start and stop with plate movement. The flow should be visably similar. Reattach the injector lines, clean the plugs and try again to start. I tend to like to error on the lean side of the basic set-up as the engine is full of fuel. Also one can easily add fuel during testing by resting ones finger on the airflap. Its harder to remove fuel (but it can be done by lifting the airflap with a needle nose pliers)

AND BE CAREFUL, you are likely to have fuel all over the place, a random spark will make it a torch*******************
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  #12  
Old 10-27-2001, 09:37 PM
scuba
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Thank you very much for your help Steve, I'll check my fuel distributor according to your information.
I checked the fuel pressure on the fuel feed line at the distributor.

Thanks again

Gunter
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  #13  
Old 10-28-2001, 07:26 AM
scuba
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Fuel distibutor

I have one question before I take on steve's advise and do a basic setup on the fuel distributor.
I purchased this vehicle in June of this year basically strait from a MB mechanic who did about $ 2,800 worse of work on the car. This included a new timing chain, new new fuel distributor, brakes and so on.
I drove the car for about a week before I started to take everything of to get it ready for a new paint job, and noticed that I always had a hard time starting it.
Before I took the bumper and all the chrome parts of I changed the Engine oil and filter, Transmission oil and filter and the fuel filter, and installed a new steering coupling since the car had quite some play in the steering wheel. Since a couple of the small rubber vacuum line's where in bad shape, I replaced them too.
Is there anything I could have done in that process for my fuel distributor to dump excessive fuel in the cylinders ?

Thanks for everybody's advise.

Gunter
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  #14  
Old 11-01-2001, 08:43 PM
scuba
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" PLEASE HELP " Still won't start

I really need some help now.
My car still won't start and I'm running out of options here. I just replaced the check valve on the fuel pump, three new fuel injectors, new coil, new spark plugs and a new ignition cable.
The injectors I replaced are the once which just squirted out fuel when I checked the compression and their fine now.
Does anybody have any ideas ?, what else it could be ?
My cylinders are getting fuel and I have a spark and it seems like when I first crank the car that it will almost start, but then the engine just turns and turns but won't start.
By the way, the compression on my engine is between 155 PSI and 168 PSI.

Any help would be greatly appreciated.

Gunter
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  #15  
Old 12-09-2001, 09:27 PM
Claude Jones
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Non starting 450SL

Gonna go with the feller on the cold start valve on this one. I do not presume to know your car, but had a very similar problem on a Volkswagen van. Drove me nuts. If none of these other suggestions work out try this: First remove all the plugs, get them dried out, and turn the engine for short period without plugs and the cold start valve connected. Leave the cold start valve disconnected (electrically only), replace the plugs and try starting the engine. This is assuming, of course, that you have good spark and that it is correctly timed. Addendum: You should check the complete cold start system. When a cold start valve, itself, fails it generally fails with an open coil meaning the valve would be closed passing no fuel. These are two wire systems meaning one wire is grounded through the controller for operation. Consequently, a failure producing an, appearently, open valve would be a failure prior to the valve such as the time-temperature switch, or hopefully not, the controller. The Bentley Series VW manuals give the best description of the Bosch Fuel Injected system and are available at reasonable in cost.

Good Luck


Last edited by Claude Jones; 12-10-2001 at 06:00 PM.
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