Hello all,

I have a 1992 300e 2.6 w 103 inline 6. The vehicle for some time now has been hard to cold start. I seem to have luck by cycling the key on and off two times to allow the pump to build pressure. Not sure but that seems to help.

Second symptom has been getting progressively worse over time. The car stumbles upon acceleration after a stop. This morning I actually needed to get on the car and it stalled completely and would not start for about 5 minutes.

This stalling stumbling problem seems to occur when the car is just warmed up on a cold morning.

I am at a loss so far on this one. Any guidance would be greatly appreciated.

Thanks!!!

How does it run once it has warmed up? I didn't catch any mention of that. Have you checked the plugs, or the OVP relay for your second issue?

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1993 190E 2.6 135k
1989 Ford Thunderbird SC 5 Spd 79K

You could start out by measuring fuel pressure. How old are the ignition components plugs, wires, cap, etc...? It might be due for a tune-up? Check engine lamp on?

Also, do you know if your engine wiring harness has been replaced? If not, inspect it for cracks as your model year is affected by this very expensive problem... If it hasn't been replaced, there isn't much point in troubleshooting the car until it's healthy again...

How many miles on your car?

-GH

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For Now:
1992 Mercedes Benz 500SL
1998 BMW 528i
2003 Honda Element
2002 CBR600F4i
1977 Coachmen Motor Home

That was a much better response than mine.

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1993 190E 2.6 135k
1989 Ford Thunderbird SC 5 Spd 79K

Thank you for your responses.

The car seems to run much better once fully warmed up. Seems odd to me that the stalling stumbling does not occur when the vehicle is very cold, rather when it is 90% to normal operating temperature.

The car has 86,000 miles. Ignition components were all replaced about 15k ago when I replaced the head gasket/stem seals.

I am very aware of the harness issues having spent some time working at a MB dealer while in college. The harness looks good to me, insulation doesnt seem to be disintegrating but who knows. I had the nightmare thought that the harness might be the culprit. At least I have not had a check engine light as of yet!

I have not checked the overload protection relay. I just checked to see if the fuse was alright. I have heard of several people just replacing this item as a tryout.

Thanks for any advice you all may have.

Possibly a temperature sensor gone bad, or a bad connection, or the wire fallen off?

When I forgot to reconnect the sensor after some work, the car was very difficult to start, but would run, badly, once started.

It affects the starting enrichment and, to a lesser extent, the running mixture once warmed up.

Just a thought, but relatively easy to check.

AJME
1989 190E 2.6

Where the coil packs replaced along with the little connectors for the plugs? If not, you may have the coils tested. The plug connectors are cheap and guys here say they are problematic.

My car's wiring harness needs replacing (diagnosed by 2 separate shops) but my check engine light has never come on. You really need to peel some of the insulation back and have a look. I was shocked at how much rot I had with only 79K miles on my '95. With only 86,000 miles, you might still be on your original harness.

OVP is also something to check as mentioned earlier...

-GH

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For Now:
1992 Mercedes Benz 500SL
1998 BMW 528i
2003 Honda Element
2002 CBR600F4i
1977 Coachmen Motor Home

* All the ideas are good but I think ajme is on the best track. If your coolant temperature sensor is broken/stuck at a hot setting, it would cause all the things you're experiencing.
* Whenever I get a customer who would like to fix up an older, higher mileage MB, even one that's running ok, I recommend replacing all the temp-related sensors on the motor. That step alone will get rid of numerous, often inconsistent and intermittant (mysterious) symptoms. And temp sensors are, for the most part, inexpensive.
* Speaking of temp sensors, I believe that $100 will buy all the temp sensors (3 or 4) in your climate control. Think of the hundreds of dollars worth of controllers and relays that use that temp information.

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ASE Master Tech
Quality Enterprises
Mercedes Svc. & Restoration
Sheridan, IN
317.769.3536

Well believe it or not I added a can of Techron Fuel injector cleaner to the fuel tank as just an afterthought to see if it would help at all.

The hard start problem is gone! I no longer need to cycle the key to prime the pump to get the car to start.

The verdict is definetely out as to the stumbling and stalling of the vehicle on a cold morning however. So far so good but I am thinking this problem will soon resurface.

To be continued.

Thanks for your ideas.

Well the Techron cleaner has in fact helped immensely with the hard start problem. The vehicle starts fine now.

The hesitation stalling issue is now very consistent and predictable. Every reasonably cold morning (I live in CA and realize it isnt really cold) after startup when the vehicle reaches its cold morning operating temp around 80 C the vehicle will hesitate. This happems when at lower RPM in first gear when given more than half throttle. This happens mostly when acclerating off from a start. If I go at it smooth and easy the vehicle runs fine. If however I need to get moving quick the car it hesitates.

The stalling only occurs when the above symptoms are occuring followed by a quick lift of the throttle. If I keep my foot in it the car eventually gets over the hesitation in the higher RPM range.

So I am in agreement with the recomendations thus far on temperature sensor replacements.

Any other thoughts with the new and more consistent symptoms.

Thanks to all!

I have a 1990 300te 103 inline 6 with 130,000 miles in CA. Similar symptoms as you. Cold morning starts would take 5 minutes then the car would run fine for the rest of the day. Cylcing the key on & off several times seemed to help for a while but the problem got progressevely worse. Occasional hesitation on acceleration and once stalled completly in traffic. I have replaced many of the parts suggested by some of these posts on past occasions. I then tried techtron in the tank, replaced fuel injectors (had them past 6 months, due anyway) fuel accumulator, fuel check valve, fuel filters. Each part I threw at the problem seemed to help and the car would perform great for about a day or two and then the problem would come back with a vengence. Another thread suggested the ignition coil so I replaced that along with the two fuel pumps. Car has now started for the past month every time the instant I turn the key.

My guess is that I had a failing fuel pump.

I know many here do not believe at throwing parts at a problem. But I try to take a systamatic approach and start with the least expensive fix first. I do not always have the time to remove each part and test it. I figure each of these parts (original to the car) are due to be replaced and once I have done so, I will probably never have to address them again in my lifetime.