'91 190E (201 chassis) 2.6**no start**
 

Hello--
I am looking at a '91 190E w/2.6L (US) for a friend. Car is currently a no-start (cranks fine). Things that he has done include: replace MAS, check electro-hydraulic actuator current/OK, check timing and Dwell/OK, check Crank sensor/OK, check 4-pin engine coolant sensor/OK, replace coil. My friend says that he can get it to start with ether--I haven't been able to. I checked the Cold start injector-no power to it w/ 10Kohm resistance in place of ECT. I've checked spark--present but appears 'weak'. I've just pulled the distributor cap--it looks 'original'--that is, worn and corroded.

I'm guessing thinking that I have two problems here--weak spark and no cold start.
As the coil has been replaced, I feel that a new cap and rotor are in order. As for the cold start valve, what actually turns it on? The ECU? I know that in slightly older models the fuel pump relay provided power, but with this unit, I haven't got a clue.

If you have any spare clues, they'd be much appreciated.

Bhill

What about fuel?
 

I think there is a fuel pump relay, but there are definatly fuel pumps, two of them. You should hear them run for a second when the ignition comes on. They are located under the drivers side back seat.

Fuel pressure checks ok...
 

just checked pressure between the two pumps-spec is, I believe 2-4 bar, actual is 45 psi--ok. Also checked fuel pressure at the fuel distributor--also OK.

Thanx

BHill

If you say spark is weak, that's what you want to diagnose first. Do the rotor, leads, plugs (do NOT use platinum plugs) if you haven't already, then perhaps check coil, trigger box etc

later

What about charging system?
 

If the distributor is original so could be the voltage regulator.

These can cause poor running problems and stalling...

Not very much money to replace and it is cheap piece of mind.

Don't even hesitate about the fuses either change all of them for something like 2 or 3 bucks.

Take off your air cleaner and have a look at the throttle body....

How long has the car sat not running?

Take a look at your spark plug wire boots, if they are corroded like mine when I bought my car, change those out and enjoy much better fuel economy and a silk smooth idle.

Good luck and keep us updated.

Mike McKinney

I just checked my records when I last checked the fuel pressure. The running pressure was 74 psi and the pressure with the car off for 30 minuits was 44psi. If your pressure is only getting to 45 psi max then I beleave that it will not start because the mechanical injectors do not open at that low of a pressure. I have a 92 190E2.6.

Rod

The pressure AT the fuel distributer was about 75 pounds. I checked the pressure BETWEEN the pumps to see if both pumps were working (that is, if the pressure had been low, the #1 pump would have a problem, and if it had been high, then #2 pump would have had a problem).

Thanks--I'm probably going to look at a new cap/rotor tuesday.....I'll keep all y'all posted--I still have to figure out why the cold start injector isn't getting a signal to open.....

BHill

I believe the OVP fuse/10 amp sends current to the cold start. Check this fuse very carefully. On my 90 190E 2.6, I had a very small break in the 10 amp fuse that wasn't immediately seen. Had someone else look at the fuse also and they saw the break.
Also, don't hesitate to replace the rotor and cap.
According to the pressures noted at the fuel distributor, you should be fine. Try using the ether/starting fluid again. I don't see why it shouldn't start with the ether sprayed into the intake.
Depending how long its been sitting, there may be some gunk in the fuel filter. Wouldn't hurt to replace it also.
Keep us all posted as to what you find.

Fixed/thanx to all.
 

Thanx to all who responded--New cap/rotor fixed it. I have no idea why the cold start injector didn't work, now does--as SHYNE and jay123 suggested, I checked most all the fuses--if these behave anything like the old volvo fuses, maybe just moving them cleared up any problems...

Yes, these MBs always have problems with the fuse connections. I would replace all the fuses in the box with new ones - it gives you peace of mind and will make sure you never have a fuse related problem again (I used to have them all the time before finally giving in and replacing them all).

later

Putting a touch of greese on the fuse contacts will prevent them from corroding and causing related entertaining problems.

Heh.. entertaining indeed, my wiper completely quit while driving in heavy rain :rolleyes:

later