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  #1  
Old 11-04-2004, 05:46 PM
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Replacing fuel injectors on an '86 300E - DIY job?

My wife owns a neglected '86 300E that has developed a chronic case of cold starting difficulty. It's often necessary to crank the starter for 30 sec. before the engine fires. Once started, the engine runs fine. Two mechanics have told me, independently, that leaking fuel injectors are the likely culprit. I'm going to try a tune-up first, but if that doesn't work, I may try to replace the fuel injectors.
Is this a task that I can do at home with simple tools and limited experience, or is this a job best left to prfessionals? What's involved?
Thanks for the input!
Mika
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  #2  
Old 11-04-2004, 06:37 PM
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Location: East Coast U.S.
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cold start, warm start

Is it also hard to (re)-start once warmed-up? If you stop the car and start it again, how does it go?

I'm not familiar wtih your car but could the cold start valve be part of the problem?
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  #3  
Old 11-04-2004, 06:52 PM
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If you warm the car up, turn it OFF, then immediately turn it back ON, it starts easily the 2nd time. However, if the car sits for more than about 30 minutes, it becomes difficult to start. I don't get it!
Mika
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  #4  
Old 11-04-2004, 06:59 PM
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Is your anti-lock brake light also on?
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-Marty

1986 300E 220,000 miles+ transmission impossible
(Now waiting under a bridge in order to become one)

Reading your M103 duty cycle:
http://www.peachparts.com/shopforum/831799-post13.html
http://www.peachparts.com/shopforum/831807-post14.html
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  #5  
Old 11-04-2004, 07:00 PM
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It has come on and off on occasion... once every few weeks. why do you ask?
Mika
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  #6  
Old 11-04-2004, 07:06 PM
Ta ra ra boom de ay
 
Join Date: Jun 2004
Location: Pittsburgh
Posts: 1,915
Quote:
Originally Posted by mwaller
. It's often necessary to crank the starter for 30 sec. before the engine fires. Once started, the engine runs fine.
Mika
Sorry I did not read closely enough. There are an OVP relay and cold start relay that can cause hard start but it would not run fine when cold.
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-Marty

1986 300E 220,000 miles+ transmission impossible
(Now waiting under a bridge in order to become one)

Reading your M103 duty cycle:
http://www.peachparts.com/shopforum/831799-post13.html
http://www.peachparts.com/shopforum/831807-post14.html
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  #7  
Old 11-04-2004, 07:12 PM
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Replacing injectors is a pretty easy job on a 103 motor. And injectors are fairly inexpensive on a 103 - used to be under $20 each (but everything has gone up so much lately). But it doesn't sound to me like bad injectors. When injectors leak down it is usually only one or two of them. And then when you start it up it runs quite rough for a few seconds - because some cylinders have fuel at start up and others don't. It doesn't smooth out for a few seconds when all cylinders get the same fuel pressure.
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  #8  
Old 11-04-2004, 07:13 PM
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Oh...
Well, it does run rough until you give it gas. It often won't take unless you pump the gas pedal while cranking. Once you rev it, everything smooths out. Not sure it that helps narrow anything down...
Mika
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  #9  
Old 11-04-2004, 08:04 PM
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Does anyone know where I can find a shop manual or instructions that would show me how to replace an injector? It looks like many of the service manuals are out of print...
Thanks,
Mika
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  #10  
Old 11-04-2004, 08:14 PM
Ta ra ra boom de ay
 
Join Date: Jun 2004
Location: Pittsburgh
Posts: 1,915
Read this first.
M103 hard start, rough idle, hesitation SOLVED
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-Marty

1986 300E 220,000 miles+ transmission impossible
(Now waiting under a bridge in order to become one)

Reading your M103 duty cycle:
http://www.peachparts.com/shopforum/831799-post13.html
http://www.peachparts.com/shopforum/831807-post14.html
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  #11  
Old 11-04-2004, 08:21 PM
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Join Date: Aug 2001
Location: Evansville, Indiana
Posts: 8,150
Mika:

Fuel injectors don't cause hard start problems unless they also cause rough running problems. If they leak into the manifold, it should do just hte opposite of what you describe -- hot starts would be a problem from flooding, accompanied by black smoke for a second, while cold starts would be slow from lack of fuel until the accumulator pumps up.

I suspect (in spite of the advice of your mechanics) that you have a bad accumulator (leaking down) and/or a bad cold start valve.

Pumping the gas does nothing but open the throttle up more, it's not activating enrichment on that car while starting.

I would have a shop check the accumulator leakdown before putting in new injectors, since new ones won't fix the problem in my opinion. Note that leaking injectors can cause a loss of pressure too, but they will dribble with the engine off.

Another thing to check is the air meter flap under the air filter -- if it' dirty, clean it out, it will stick closed cold and cause a no start condition due to no fuel delivery. You can test that by pressing down gently on it while you wife tries to start the car -- if it starts right up, thats the problem.

I would also check for vacuum leaks -- the idle control hoses are a common culprit (and the cold start valve plugs into one of them). If they are hard, replace them, it may cure the hard start.

ABS light coming on means the overvoltage protection relay is bad, replace it (I'd do that anywhat, as it is probably bad unless replaced already). If the fuel pump relay gets hot, replace that, too! -- you don't have an intermittant stalling problem do you?

Peter
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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!
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  #12  
Old 11-04-2004, 10:52 PM
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Location: Phoenix
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Quote:
Originally Posted by mwaller
Does anyone know where I can find a shop manual or instructions that would show me how to replace an injector? It looks like many of the service manuals are out of print...
I can think of 3 sources - the search function herein, seems to me like there has been some good posts on changing 103 motor injectors, 2) the Haynes 124 manual, about $35 @ 303-237-0911, and the 124 service CD, available from the dealer or sometimes on Ebay for less. I don't it's a bad idea to replace the injectors - they're not that expensive on that car and they're easy to replace. That may not be the principal problem - but you'll have new injectors. If original they're probably on their last legs anyway.
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  #13  
Old 11-05-2004, 12:12 PM
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Thanks, everyone, for the great info!
Mika
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