90 300E 3.0L Won't start - PeachParts Mercedes-Benz Forum

Bobcin5859 · #1 10-09-2010, 01:14 PM

Anyone,

My car won't start unless I depress the air sensor plate a slight amount. Then when I let go of the plate, it stalls.

I initially misdiagnosed the problem as fuel pump and replaced the pumps and accumulator in the back.

My Calfornia model with the counter is blinking codes: 7,10 and 27.

The car started to hard start over a 30 day period, then the idle got bad and lastly it just won't start.

Recent, 5 months, R&R includes, plugs, rotor, caps, wires, air filter, all new vacuum lines, OVP relay, O2 sensor, hoses for the Idle Speed Valve on both sides, water pump, radiator, fan clutch, bearing bracket, idler pully, belt, power steering pump reseal, vacuum pod job, instrument cluster renovation, paint job, wheels and tires, interior reconditioning by the people who prep cars for used car delaers - So clearly Im in for the long haul.

Im about ready to have it towed to my local independent Benz Doctor.

If anyone has any insights, let me know. Thanks

ps2cho · #2 10-09-2010, 01:49 PM

Does it start ok when warm?

Bobcin5859 · #3 10-09-2010, 02:55 PM

Thanks, it hasn't moved since it died in the garage.I can't keep it running long enough to warm.

ps2cho · #4 10-09-2010, 07:23 PM

Are you absolutely sure the idle control hoses are intact? Sounds like a vac leak...Since if you increase the air and fuel via pushing the throttle open the car runs, something weird is going on.

Bobcin5859 · #5 10-09-2010, 09:14 PM

Thanks, tomorrow I will go back make sure the idle air valve hoses are fully connected.

Bobcin5859 · #6 10-10-2010, 11:32 AM

Bingo! The Idle Valve Hose on the air side was on, but split down the entire length of the nipple. This is odd since it was a new hose from Autohouse AZ.

A Massive Vacuum Leak it must be.

Unfortunately, all local European part stores are closed and I will have to wait until tomorrow.

PS2CHO - thanks for the insight. After I change the hose I will fire it up and confirm good operations. Also, after that I will change a few more variables: new Injectors, insulators seals and o rings and used but new looking Fuel Pressure Regulator. Then I will attempt to address duty cycle with a volt meter.

If you know of any good references for the volt meter ratio adjustment, please pass it on.

Again, thank you PS2CHO.

ps2cho · #7 10-10-2010, 01:10 PM

Yeh....ask me how I know....

Reason for this -- AutoH carries the URO for that particular item. Chinese Junk. I replaced all mine with URO about a year ago and it split on me a few months back and I had the exact same symptoms.
Replace it with an OE hose. It sucks since its about $15 @ the dealer, but at least you know it will last a lot longer than 6 months that's for sure.

I always wondered if there was a product that would prolong the life of these hoses by keeping them supple...?
You can always wrap some tape around the hole if you need the car today, although it sounds like a bad crack.

Why do you think you need a new FPR? They generally never need to be replaced. If the diaphragm is broken inside you will see raw fuel going through the vacuum tube out the other end. If you don't see that, I would leave it alone.

You check the mixture via the X11 connector on the driver-side fender. Unscrew the cap and probe pin's 2 and 3. (2 is ground...3 is the mixture ratio). You want 50% or ~.65v fluctuating.

Bobcin5859 · #8 10-11-2010, 04:10 PM

Confirmed - the problem was the idle valve hose to the air intake.

Replaced it and it runs great.

I also replaced the fuel presure regulator because it was missing the rubber connector to the tube that went onto the air breather hose. I wasconcerned that if the diaphragm failed, I'd self emolate like a VW. Got a great deal on a used one, so I cahnced it. Turned out super.

Again, thanks to PS2CHO for the insight - it was on the money. In two weeks I'm moving on to the injectors. Why replace them, some might ask - because they are there and it's one more major future failure off my mind. After all, I did buy this car, instead of a new one so that I could work and think outside of work.

ps2cho · #9 10-11-2010, 05:17 PM

Not sure what mileage you are at, but being proactive is always good if you can afford it and the car is long term. The earlier injectors can be replaced for ~$150 which is pretty reasonable compared to the later models.

I've found these injectors can last anywhere from 90-150k.

Can't find the thread, but somebody talked about how Chevron Techron injector cleaner product is close to useless for CIS systems. Put a good dose of Redline Injector cleaner since it is uses more PEA detergent compared to Techron.