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  #1  
Old 10-11-2002, 02:41 PM
buddysdad5005
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Question 90 300 E Fuel Injectors

I have a 90 300E and my local shop says that the reason my car starts rough is that the injectors are not holding the fuel while the car is off. He says there is a pump that keeps a small pressure on the fuel to keep it ready to fire upon startup. And that when they leak some fuel into the cylinders, its like a mini flooding. And that's why it starts rough. It runs fine once its running.

Ok after all that....

My question is...I see the fuel injectors on line to purchase and they are not that expensive. The injectors seem pretty easy to get to on this straight 6....

Is changing the injectors something I could do myself or are there many tricks that could cause alot of problems if not done right.

I would like to try if it's feasable.
Maybe a good shop manual could help?

Thanks
Steve
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  #2  
Old 10-11-2002, 03:13 PM
J.HIDALGO's Avatar
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Location: Jax, FL
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It is a DIY project.

However, use all the precautions while working with fuel i.e. Disconnect the battery. Also change the all the seals associated with the injectors.
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'86 300E
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  #3  
Old 10-13-2002, 04:28 PM
buddysdad5005
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Looking for Help....

I have decided that I relly need ot change the injectors.

If anyone has any diagrams on how to do this I would really appreciate the help.

Thanks
Steve
90 300E
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  #4  
Old 10-13-2002, 05:29 PM
Jackd
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There is no ''little pump'' keeping the pressure on.
That' the fuel accumulator job's to do that.
My opinion, your troubles are not caused by leaky injectors
JackD
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  #5  
Old 10-15-2002, 08:10 AM
buddysdad5005
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Diagnosis..??

Thanks for the opinion...
If the injectors are thought to be ok, what then could cause the car to cough and sputter so much when it is started until it is running?

Thanks
Steve
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  #6  
Old 10-15-2002, 02:48 PM
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Join Date: Apr 2002
Location: Portland Oregon, USA
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Hmm... Same here

I have the same symptom on my 92 300e (2.6).. On most attempts to start the car, the car hesitantly shakes/runs rough for that first initial second-or-so of startup, then it runs great.. I replaced plugs and ran Techron Fuel cleaner in the tank, which hasnt helped.. I too am considering replacing the injectors, because of their low price.. (and, they *appear* at least, to be easy to replace)... What other areas of the M103/M104 engine could cause this odd initial rough running of the engine during startup? Could one suspect the fuel pump(s) perhaps?? (don't these cars have like... 2 pumps?) I'm stumped!

-Miles

92 300e 2.6
120k
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  #7  
Old 10-15-2002, 05:06 PM
J.HIDALGO's Avatar
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Long shot but, try this...

Turn the key until you have all the dash lights on but DO NOT start the car. You should here the fuel pump activating. Wait a few seconds (the longer the better) then try to start the car. If it starts with no problems you have a fuel pressure leak somewhere, most likely the fuel accumulator, check valve at the fuel pump, leaky fuel injector/seal among other things. If you want more specific help, have your mechanic do a fuel pressure test...Good luck!
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  #8  
Old 10-15-2002, 07:31 PM
Jackd
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Like the previous post said , a fuel pressure (leak down) test would most likely identify the problem. But there could be so many other reasons for your problem:
*Ignition system (cap, rotor, wires, spark plugs (only use OE, not any other make/type.)
*weak coil
*Cold start valve
* temperature sensor,
*vacuum leak
*Fuel pump, (2)
*Fuel accumulator
*Fuel filter
* Others less likely:
* Stretched timing chain
*low compression
You really have two options:
1) Throw parts at it until you are lucky enough to replace the right one.
2) Have a good/solid diagnostic made by a knowledgable/competent pro.
In most cases, solution no.2 is less expensive.
Good luck
JackD
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  #9  
Old 10-15-2002, 10:53 PM
ILUVMILS's Avatar
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Hey buddy How long long does your car have to sit before it starts rough? If it sits all night and then starts rough, and then clears up after a few seconds it's probably a leaky injector(s) or leaky fuel distributor. If it starts rough after only a short time of being off, it's probably a REALLY leaky injector(s) or fuel distributor! Have your mechanic connect a fuel pressure guage and verify correct pressure when running, and then shut it down. If there is a large pressure loss that will eliminate an ignition problem. You may need to keep the pressure guage connected overnight. If you find a pressure loss it's easy to determine if it's a bad injector. You can remove the injectors and re-connect them to the fuel lines, and then turn on the key to pressurize the system( don't worry, they won't spray unless the air flow sensor plate is pushed down ). If any nozzles are leaking you'll see droplets on the tips. If no droplets form, the leak is someplace else ( most likely the fuel distributor). If you lose fuel pressure rapidly, the check valve in the pump is probably bad. Don't forget to check the distributor cap and rotor! You'd be surprised how often this is overlooked! Good luck and let me know how you do.
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  #10  
Old 10-15-2002, 11:55 PM
buddysdad5005
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Lightbulb The diagnosis sounds right

Thanks for the help...

Your analsys sounds correct. The car must sit for a while before it starts rough. An immediate restart is "fairly" smooth. But when is sits over night...It's a bumpy morning! So I really believe it is one or more injector.

I am going to order the injectors, seals and clips tomorrow from my on-line parts place and I should have them by Friday.

I am one of those visual kind of guys...If I can see the steps on paper and then in my head I can do the job. But if I can't visualize it..It's a rough task. That's why I keep hoping that someone has had experience changing injectors and would be willing to share some steps...written or visual.

I'm going to get a Hanes manual tomorrow and hope that will help some.

I'll report to you guys in the forum after the jos is done and let you know how it goes. Hopefully, I'll be able to do the job this weekend.

Thanks again for all your help.
Steve
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  #11  
Old 10-17-2002, 12:31 AM
bareftr02
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I have a 92 300sl with the same symptoms as your 300e. I took it to a mechanic who replaced the fuel filters, checked the fuel pumps and determined the rough starting was caused by the injectors. Instead of replacing them he cleaned them and told me to drive the car. It didnt run much better. ($400 later)

He told me the next step would be to replace the injectors. (another $400) It looks like a easy project. Please let me know how you job turned out.

p.s the prevoius owner of my car took it to another mechanic who replaced the timing chain and then told me the next step was to replace the fuel pumps. Its hard to find good mechanics.
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  #12  
Old 10-17-2002, 12:57 AM
Kyle Blackmore's Avatar
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Location: almost beyond Hope...B.C.
Posts: 897
88 300CE

I'm experiencing the same rough hot starts,though mine won't pass the idle test of our Aircare program.I failed miserably the first oh so innocent trip through,took it to a local import shop and he said O2 sensor,bring it back next week .So I replaced it myself and tried again,failed,but only the idle test this time.Hmmmm,pulled the plugs and noticed they were NGK resistors ,in went Bosch Super's and a bottle of snake oil guaranteed to make your exhaust cleaner than clean,failed again.
So I went by the repair shop today,really nice guys btw at Valley Eurotec in Abbotsford,and they figured it was the injectors being worn out,sputtering too much fuel at idle,making it fail the idle test.It's going in on Friday to have injectors installed ($240+ labour)and another Aircare test (@$24ea).It BETTER pass!!
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  #13  
Old 10-17-2002, 01:06 AM
buddysdad5005
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Injector mania !

3 local autoparts stores turned up a ZERO for the Haynes manual. Undaunted, I will pursue further tomorrow (phone this time). I have found the injectors online for 23.81 ea. + 1.10 for each seal and about 3.00 for each holder that totals about $167.00 for parts. Including shipping. Not Bad!

Had a weird one today...started smelling a burning (i thought) through the vents so i stopped..and the battery sizzling and was spitting fluid out the side! Yikes! pulled it before it blew. I've never seen that before.

Steve
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  #14  
Old 10-17-2002, 01:29 AM
Kyle Blackmore's Avatar
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Join Date: Sep 2001
Location: almost beyond Hope...B.C.
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Hi Steve,I don't know if Haynes makes a 124 manual,if you find one let me know.I have the MB cd but it's a pain to use sometimes.
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1985 380SE- 160,000km 'Blistu' - Sold
1988 300CE- Eva,my garage mistress
2007 R350 4matic- The Black Pearl
2011 Ford Ranger-Work truck
1974 25' Trojan Sea Raider- 'Grannyknot'
2002 215 cm Atomic DH skis- Canadian SDH record holder, 175.5km/h- Vars 2010
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  #15  
Old 10-17-2002, 07:01 PM
ILUVMILS's Avatar
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Hi Buddy Save your money and forget about the Haynes manual. It won't help you with replacing the injectors. Let me give you a few tips that will make the job a piece of cake. Remove the gas cap. Residual pressure will cause fuel to dribble out of the lines long after they're disconnected. Crack the lines loose at the top of the fuel distributor just a bit to bleed off system pressure. Be careful when you loosen the lines at the injectors. Look carefully at the bracket that holds the injector in place. When you turn the 14mm fitting, sometimes it spreads the bracket open before it comes loose. A 16mm open end wrench fits perfectly around the outside of the bracket and keeps it from spreading. Once the lines at the injectors are loose the hardest part is over. Loosen the lines at the top of the fuel distributor a few turns and this will allow you to easily move the lines out of the way when you pull out the injectors. The 5mm allen screws that fasten the brackets to the intake manifold can be a bit stubborn sometimes. Make sure you use a quality tool for this step. There isn't much room next to the fuel distributor to get at the screws. A 1/4 " drive bit and ratchet will make it easier to loosen the allen screws in this confined area. Use a bit of lube ( anything will do ) when sliding the new seals onto the new nozzles and DON'T FORGET TO REPLACE THE FUEL FILTER! It's really a simple job if you take your time. Good luck and let me know how it goes.
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