Mechanics

REPEATED ENGINE FAILURE

1990 Mercedes Benz 300ce

Engine Performance problem
1990 Mercedes Benz 300ce 6 cyl Two Wheel Drive Automatic 50,000 miles

Our very low mileage vehicle loses engine power about 5 miles after starting. It does not respond to further cranking. Points to note are -
1. If ether is fed into the air inlet, the engine fires.
2. The motor starts up quite normally after about one and a half hours and then performs normally.
On the electrical side -
a) The ECU has been checked out and is OK.
b) Coil replaced
c) Plugs and leads replaced
d) Battery peplaced
e) Voltage overload replaced
f) Top dead centre sensor replaced.
g) Rotor button and spark suppressors replaced
h) Immobiliser removed to check if it at fault. It was not. Replaced
On the fuel side -
A) Filters replaced
B) Tank removed and was clean
C) Fuel pumps replaced 1 years ago.
D) EHA replaced
E) Recon fuel divider fitted
F) Fuel pressures tested
None of fixed the problem.
Any help appreciated
Avatar
Bilsun
January 8, 2009.




Dr. Haggerty is probably the best mod for this, but I'll throw in a thought.

When it isn't starting, was the fuel pressure tested then?

When it isn't starting, was the ignition tested for spark?

Fuel pressure has not been tested at failure which occurs on open road. On reflection, there is no strong smell of gasolene that might be expected with repeated engine cranking
Spark has been tested at the coil where a strong blue spark is noted. As the engine fires is fed with ether, spark is available.
AD

Tiny
Bilsun
Jan 9, 2009.
Interesting.

What brand of fuel pump was it replaced with last year?

Fuel pressure needs to be checked during failure time.

Mercedes Benz (local subsidiary not an agent) worked on the car in June 08. They replaced -
1. 2 fuel pumps
2. 1 filter
3. 1 EHA control unit
4. 6 seals
They supplied the parts and there is no reason to suggest that they are not of Mercedes origin. Pump part number is MBA0020918801. Maker is not known but will check further. Is there a preferred manufacturer? Mercedes indicated traces of water in tank which was cleaned. Source of water unknown and tank was removed in November to check for blockages and was found to be clean.
The above action has not improved the situation and it has worsened slowly. It seems to be slightly worse if the vehicle is left standing for a week or so.
The desire to check pressure when stopped is understood. Can easily fit light up to fuel pump and tell if pumping. In time taken to have vehicle towed to workshop, problem has rectified itself. Is there an easy method of measurement in situ?

Tiny
Bilsun
Jan 10, 2009.
OEM part is preferred and you have that.

The best way is to talk to the service manager and ask that he use it a personal vehicle with a gauge hooked up so it can be monitored when it happens.

Intermittants are brutal if the don't happen in the shop.


AD