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Old 01-03-2007, 12:13 PM
Registered User
Join Date: Jan 2007
Posts: 3
Another cold hard start problem

Hi, just joined after reading the threads pertaining to my problem and I've checked the OVR, cold start valve, the dist. cap, rotor, plugs, wires, O2 sensor, pickup from flywheel, throttle switch and also bought new battery. This thing will start: I try it 1st time for 20 sec. will not try to fire. Wait 10 min try again this time pedal 1/2 way down after 3 sec. and it tries to fire. Wait 10 or 15 min and try again. This time with no pedal it starts to go and will if I give it a slight bit of pedal. Also, this thing gets terrible milage. I don't know where to go from here. Please help!

PS- Fuel tank has been dropped & cleaned,new filters,new temp sensor.

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Old 01-03-2007, 12:37 PM
Registered User
Join Date: Jul 2003
Location: Montreal, Quebec
Posts: 508
How about fuel line check valves?
First, I'd check fuel pressure.
The fuel pressure at the pump outlet should be around 5 bars when the pump (or pumps) is running.
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Old 01-18-2007, 11:58 PM
Registered User
Join Date: Jul 2005
Posts: 18
possible items..

my ovp relay was fine but, the connections it plugs into were completely corroded. A quick trip to the local wreckers, a pair of wire cutters, and a smashed 89 300e later - then a couple of hours soldering in 'new' relay recepticle (did the fuek pump relay one and while I was at it) -- all is well.

another issue was the cold start valve some 2 years later - I thought it was working but it made a huge difference once replaced. I posted info on that earlier today - you should be able to see it.

Anyway - ideas.
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Old 01-19-2007, 11:27 AM
david s poole
Join Date: Mar 2005
Location: dallas
Posts: 1,822
did you replace ovp relay or just check it and if so how did you check it?
David S Poole
European Performance
Dallas, TX

"Fortune favors the prepared mind"
1987 Mercedes Benz 420SEL
1988 Mercedes Benz 300TE (With new evaporator)
2000 Mercedes Benz C280
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Old 01-19-2007, 01:47 PM
Registered User
Join Date: Aug 2006
Posts: 141
Hard start 300E

What year 300E? Those 300Es equipped with 104 engines have a fuel pressure regulator on the fuel rail,with time they develope leaks and flood the engine while sitting.
If so equipped remove the vacuum line and look for ANY fuel coming from the nipple, If you get any fuel from the nipple replace the regulator.
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Old 01-19-2007, 04:10 PM
Registered User
Join Date: Jul 2005
Posts: 18
I did not replace it - the new connections seemed to cure the problem. I know for 86 the 'weather' protection for those relays behind the battery was very poor - in fact the newer design of plastic rain gutter above the OVP/fuel relay etc. includes a rain gutter of sorts to direct the rain away from hitting the relays and running down to the plug/pin area. (I took one from that same wrecked 89 and now it's protecting my repaired connections) Also - this may be risky - but I suppose one could bypass the OVP relay with a wire into the correct pins for test purposes only. If that seems to cure it then sounds like the OVP may be the issue?
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Old 01-19-2007, 04:12 PM
Registered User
Join Date: Jul 2005
Posts: 18
I forgot to mention - I didn't know the OVP was fine - I just know the plug was very suspect and decided to fix that first which solved the issue.
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Old 01-25-2007, 05:47 AM
Registered User
Join Date: Jan 2007
Posts: 3
I've been off the internet for about 2 weeks due to the winds here in So. Cal. During this time, the car sat for 4 days. I pulled it over to my dads house and replaced the crankshaft position sensor. I turn the key to start it and in .5 seconds it starts. It has never started this easy. After a 20 minute drive, I shut it off and turn in for the nite. Get up at 4:30 AM and it will not start! This thing is causing me such mental anguish, it may end up at the bottom of Cadillac Cliff here in Riverside CA. I tested the OVR as per the service manual.
Is it possible for that relay (OVR) to be bad without triggering the ABS light?
Does anyone know the purpose of the sensor located just above the harmonic balancer. It has a wire running from it that goes to ? (will trace it in AM)
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Old 01-25-2007, 06:08 AM
Registered User
Join Date: Jan 2007
Posts: 3
It is a '91 and has no fuel rail- fuel injection system is the ElectoMechanical type.

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