QuestionPLEASE HELP! I OWN A 1997 MERCEDES E 300D AND THE CAR WILL RUN FINE FOR 3-4 WEEKS AT A TIME AND THEN DOES NOT WANT TO START. I HAD THE INJECTION PUMP O RINGS REPLACED AND IT WAS BENCH TESTED BY A REPUTABLE SPECIALIST. WHILE THE INJ. PUMP WAS OUT, I REPLACED ALL THE GLOW PLUGS AND A NEW FUEL FILTER WAS INSTALLED. THIS PROBLEM IN VERY INTERMITTENT, THE CAR WILL DRIVE LIKE A DREAM, AND THEN A SHORT WHILE LATER, WILL NOT START UNLESS YOU GIVE A SHORT BURTST OF STARTING FLUID. COULD THIS BE A RELAY OR ELECTRONIC PROBLEM? ANY HELP WOULD BE APPRECIATED. THANKS IN ADVANCE.
AnswerBest guess = Typical E300 fuel problem.
Answer: Sucking air:
There are rubber O rings on the (roughly 19mm) plastic insert attached to the top of the fuel filter housing, between fuel filter mount bolt and head, return fuel flows through the tube, transitions through the insert, and is returned to the fuel filter.
You remove the tube, remove the retainer, and remove the transition insert to replace O rings.
I can not recall if there are three or four O rings, replace all other O rings on fuel filter housing lines.
Inspect all plastic fuel lines for age cracking, yellow clouding and abrasion wear, replace if any of these signs are found.
With the car on a hoist; inspect the main fuel lines for any visible leaks under the car.
Question: When you remove the fuel tank cap, does it blow pressure out, or suck air in?
Check under all fuel line mounting clips for signs of corrosion = micro pin hole = vacuum leak only = sucking air.
Check rubber fuel hoses from fuel tank to steel lines for signs for age cracking or ANY trace of dampness = micro pin hole = vacuum leak only = sucking air.
Clean or replace the fuel tank vent, if equipped with one.
