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  #1  
Old 12-29-2001, 06:40 PM
daniel
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Angry 1978 450SEL To much fuel

1978 450SEL 4.5 liter getting to much fuel. The car stop running. I pulled the plugs and they were all fuel wet. Determine that all the plugs are firing but much fuel coming out of the cylinders when turning over the engine. Is there a quick way to try and pin point what may be the problem? Trying to determine if its the injectors, fuel distributor of cold start valve!

Thanks!
Just put a new fuel filter on it, I thought it was being starved. When I ran the capacity test I got 1.5Liters in 40 seconds.
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  #2  
Old 12-29-2001, 10:24 PM
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Join Date: Mar 1999
Location: Suwanee, GA, USA
Posts: 4,712
I would hot wire the fuel pump and check for the leak. You can pull out the cold start valve to see if it is open all of the time.

BEWARE! Do not do this for long periods then try to start the engine. Liquid lock will bend rods!
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  #3  
Old 12-29-2001, 11:02 PM
scuba
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Daniel,

I have the same problem with my 1980 model 450 SL. I also installed a new fuel filter among a lot of other things.
My fuel distributor would not adjust, it would always supply fuel to the cylinders when I jumped the fuel pump.
I'm getting my new fuel distributor next Friday and hopefully that will solve my problem.

Gunter
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  #4  
Old 12-30-2001, 01:44 AM
daniel
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I am not sure I understand what the issue is with hot wiring the fuel pump. The pump seems to run as soon as the ignition key is put in the on position (just before starter). Are you saying if I turn on the ignition so that the pump is pumping that I should get no fuel pumping through the injectors? So if I crack each of the injector line no gas should surge out? Is the pump only suppose to run for a few seconds until you hit the starter? There is a distinct whinning sound coming from the fuel distributor!
Thanks for the help!
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  #5  
Old 12-30-2001, 08:16 AM
scuba
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Daniel,

When you turn the ignition on, the fuel pump runs for a few seconds to build up pressure. But at this time no fuel should go to the injectors or the car floods.
This is exactly what my car is doing, its flooding before I crank the engine.

Gunter
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  #6  
Old 12-30-2001, 10:22 AM
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Join Date: Jan 2000
Location: Maryland. USA
Posts: 180
Daniel,

Need a bit more info.

Has the engine been serviced recently? If so, details please.

Did this happen right after:
- purchasing a tank of gas?
- you poured in a fuel additive?
- poured in the remaining gas from a gas can?
- you loaned the vehicle to someone else?

If this is something out of the blue go to your local autoparts house and purchase Bentley's "Bosch Fuel Injection & Engine Management" book. ISBN 0-8376-0300-5. It's a wonderful compliment to the Mercedes shop manuals.

Hang in there.
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2000 G500 LWB Obsedian Black
2005 Toyota Tacoma Access Cab Off Road Sport
1993 Volvo 240 Sedan Anthracite
1980 450SEL Champange (owned it for 15 years. Great car)
1986 280GE LWB Anthracite (Sold it and kinda wish I hadn't)
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  #7  
Old 12-30-2001, 07:31 PM
daniel
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I just started doing it out of the blue. I noticed before it happen that I had to move the gas peddle around to maintain a constant speed!
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  #8  
Old 12-31-2001, 09:17 AM
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Join Date: Jan 2000
Location: Maryland. USA
Posts: 180
Daniel,

I own three vehicles all with Bosch fuel injection. Based on my past experiences and to a much greater extent, Benzmac's, I would put the cold start injector at the top of my list. However, don't go down this path without a service manual. If the injector is simply leaking, then it's a simple diagnostic. But if it's not, there is an electrical logic path that needs to be worked through.

For this job my Haynes/Chilton's has enough info. If you don't yet own the Benz service manuals, get them (they sell them at this site on CD). They will pay for themselves within a job or two, not to mention the number of parts it will save you by not doing the "blind squirrel" method. Also, your public library will have automotive maintenance manuals. THey usually have the jobber type (the brand name escapes me right now).

OBTW, double check that the airflow sensor plate moves without friction. If the plate has a lot of gunk around it, clean it off with a good carb cleaner. The clearance between the plate and the body is minimal and sometimes gunk builds up and causes it to stick.

Keep us posted.
__________________
S, J.R. Brown
2000 G500 LWB Obsedian Black
2005 Toyota Tacoma Access Cab Off Road Sport
1993 Volvo 240 Sedan Anthracite
1980 450SEL Champange (owned it for 15 years. Great car)
1986 280GE LWB Anthracite (Sold it and kinda wish I hadn't)
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