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Old 02-18-2000, 07:52 AM
Registered User
Join Date: May 1999
Posts: 33
Car : 94 S420 with about 80,000 km.

Problem : Car starts easily while cold (ie sitting overnight). When the engine is hot, it is easy to restart (ie restart within about 5 minutes of shutting off the engine). When the engine is warm (ie. sitting for about 30 minutes) it takes about 10 to 12 seconds to restart.

Fixes thus far : replaced fuel pressure regulator (at the fuel rail) and replaced check valve at the fuel pump under the rear of the car. There was a bit of rust on the old check valve.

What's the next thing to check?


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Old 02-18-2000, 09:20 PM
Registered User
Join Date: Mar 1999
Location: Suwanee, GA, USA
Posts: 4,712
Take out the distributor caps!!!! They fail often!!! If any green is inside get new caps and rotors. They have been updated. (We sell 'em)

1981 280GE SWB
1987 16V

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Old 02-18-2000, 10:52 PM
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Join Date: May 1999
Posts: 33
Thanks for you reply. I really feel like kicking myself now. That's the answer that the local benz dealer mechanic told me, but it didn't make sense to me. That's what I get for second guessing the guys who know.

Thanks again.

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Old 09-29-2000, 12:50 AM
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Join Date: May 1999
Posts: 33
Well, finally got around to changing the distributor caps & rotors. The points on the old ones were green.

However, the problem of being hard to start persists. After the car sits for about 30 mins, the engine cranks for about 15 secs before starting. Left overnight, starts right away. Any ideas?

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Old 09-29-2000, 01:10 AM
unkl300d's Avatar
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Join Date: Jul 1999
Location: San Francisco, Ca
Posts: 2,207
Spark plugs overlooked?

1979 300D
133K miles
1989 300SE
1995 C280
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Old 09-29-2000, 10:03 AM
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Join Date: May 1999
Posts: 33
Plugs, fuel filter were changed. Injectors cleaned.
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Old 09-29-2000, 10:51 PM
Posts: n/a
Still sounds like fuel pressure leakdown to me. Do a fuel pressure test. Test it while running and test it when you shut it down. See if the pressure is droping too quickly when it shuts down. If the pressure gets too low with a hot engine/injectors, the fuel will vaporize causing vapor lock. Engine won't start until pressure is built back up and vapor is expelled.
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Old 09-30-2000, 02:32 AM
akry's Avatar
W140 Maniac
Join Date: May 1999
Location: Burnaby, BC, Canada
Posts: 960

I have a similiar problem with my car, too. However, when I start the car warm, and engine starts right away, but when the rpm would dropped down below 500rpm, and went back to normal idle. By any chances if the engine stalls, the car won't start no matter how you try, and would have to let it sit for 30 min or so, and the car will run again just fine. So far, my local MB has clean up the distribution caps(which I replaced in 1998). But the problem happens once in a while still....any thoughts??

Note: It only happens if the car is warm...

Andy Kuo

<LI>1992 Mercedes-Benz 400SE
<LI>Pearl Grey/Black Leather
Mercedes Owners ICQ ActiveList ID#61730549
Mercedes S-Class Page
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Old 10-01-2000, 12:08 AM
Posts: n/a
i have seen some previous postings with this symptom suggesting an EHA leaking problem...
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Old 10-08-2000, 11:16 PM
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Join Date: May 1999
Posts: 33

If it is a pressure leaking problem, what part failures would cause that?


What is EHA?

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Old 10-09-2000, 10:09 PM
Posts: n/a
Could be the fuel pressure regulator; check valve; or a fuel injector leaking. However, you've stated that you've replaced the regulator and check valve. I would do a pressure check before I spent any more time or money on this problem. If it's not a fuel problem, that will tell you. It's an easy test.

[This message has been edited by ARJAY (edited 10-09-2000).]
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Old 10-09-2000, 10:20 PM
Posts: n/a
You may be loosing enrichment via Base control module. Have the vehicle checked for codes. If the base module is bad of one of the fuses blown, you would exhibit hard starting cold.
Good luck

Mercedes-Benz Master Guild - 2 years
Shop Foreman - 20 + years - dealer.
Part owner - MBZ Transmission remanufacture
2000 SL500
1995 E320
1989 300SE
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Old 10-10-2000, 10:26 AM
Posts: n/a
To Marlboro:

EHA stands for "electro-hydraulic actuator"..
Search Tech Help, there are topics discussing the EHA....
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