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74 450SLC Euro , 72 350SL Euro , C180 Estat W205 , ML500 W164
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96 Posts
Discussion Starter #1
Hi folks
I bought a nice w164 ML500 2006 here in Brazil. Car is fine 70.000 km , but the previous owner told me to not drive with less than 1/4 fuel because the engine will die in random situations. This anomaly started couple months ago . I tought it was a fuel pump related problem and got a new one from ebay during my last trip to USA last week.
Google the DIY job only to realized that there is also an fuel filter on the other side of the fuel tank. Should buy the filter too....
After changing the fuel pump , car wont start. I can hear the pump prime each time I turn the key. There is some fuel flow but no pressure. 0.6 bar only at fuel rail port. if I pour some gas at intake car will start and run for 5-10 seconds. So I believe there is spark and CPS is also good .
I removed the whole fuel delivery system from the car, pump , filter, tubbings etc... To bench test them. Powered the pump alone = almost 7 bar at pump outlet (both pumps, old and new) . after that I connected the tubbings and clocked the pressure at fuel filter outlet , same 0.6 bar clocked in fuel rail.
I am assuming the problem is at the filter side. Next I opened the filter housing to check the inside paper filter element. It was dirt but nothing absurd. Just to test the whole thing ,I put all housing parts together but with NO paper filter inside. Still no good. There is some fuel flow but no pressure. I can feel a lot of resistance ( by blowing) in the brown tube going to filter. Inside the filter housing I can see a small metal valve next to this tube. This valve must stay open or closed? I can bet it is almost closed now.
All fuses in engine bay are OK. Battery is brand new. Any help is more than welcome
 

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Registered
74 450SLC Euro , 72 350SL Euro , C180 Estat W205 , ML500 W164
Joined
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96 Posts
Discussion Starter #3
Solved! Problem was that small check valve inside fuel filter. New filter, truck is good again.
 
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