lclimited1

i have an Ml500 it started stalling randomly and taking a lot of cranking to start. So I put in a Bosch crank sensor. That took care of the stalling but not the excessive cranking so I bought another crank sensor Bosch from a different location and it performed the same ie. no stalling but still long cranking. I got to playing around and found that if I turn the key on wait 10 sec. Then off then on for 10 then off then on for 10 and turned to start she fired right up so I figured fuel pump so replaced fuel pump Bosch and still long cranking unless I do the key cycle. Is there a back flow preventer or check valve on the car. I always thought check valve was part of fuel pump. Please help

Maj. Dundee

There is a check valve in the fuel pump and another in the fuel filter. You should have replaced the filter when you changed the pump.

lclimited1

Thanks maj. I'm from the old school where a filter was just a filter. This lesson will make me very fast at this operation. I ordered a filter after ur reply oh wise one.
Thanks sir.