It's possible the fuel check valve is bad. Search for that on here. Is fuel two years old?

 

Replaced that today with no change . What has me stumped is there is plenty of pressure at the fuel rail after running the car and turning it off . Even 15 mins later . With the gauge showing 45 psi after 15 minutes it’s still takes a lot of cranks to start ? What else could cause this ? Read somewhere the ICV could be the culprit? The car runs and drives very smooth with no lag or sputtering . The problem seems to be intermittent with the hard to start issue .

 

You need a new fuel pump. Don't buy aftermarket - VDO only. Get the filter later.
18 to 20 is a failed pump, nothing to do with the filter.

The pump is not driven by the engine. It is supposed to provide constant 50psi at all speeds, including primed with the engine off, and has no variable output. So if it is not providing it when priming it, it is not working.

 

It puts out 50 - can't be that tired. If it won't hold residual pressure, could be check valve. And yes, that's in the pump, but Someone on here used an separate inline valve. If money is tight.

 

Delphi will work too.my E53 3.0 has Delphi as OEM.

 

Filter’s a super cheap and easy thing to replace. I doubt that’s the problem, but if you have any doubts about it just replace it. A quick look shows a Bosch for about $40 at FCP.

 

It's not 'just' a filter, it has the pressure regulator as well. The Boschs are hit and miss here, while the Kayser is $58.99 right now on FCP and is OE.

OP, what was the replacement filter brand?

Here is a recent Bosch fuel pressure regulator that after only 500 miles leaked fuel through the regulator diaphragm and flooded the intake with fuel.

https://www.e46fanatics.com/threads/fuel-coming-out-of-fuel-filter-vacuum-line.1323021/post-19211343

 

Maybe time for smoke test to check your work on various gaskets?

 

It's possible the fuel check valve is bad. Search for that on here. Is fuel two years old?

Replaced that today with no change .

You replaced the entire fuel pump?

The car runs and drives very smooth with no lag or sputtering . The problem seems to be intermittent with the hard to start issue .

So no more running issues (lack of fuel at full throttle mentioned in post 1), just occasional hard starts?

 

Correct no more cutoff at high rpm’s . I didn’t replace the fuel pump I just put in a check valve . The problem ended up being a bad spark plug on cyl 5 . But still having intermittent hard to start issues .

 

Sad looking plug. Where did you get check valve?

 

Amazon . Think it was about 9 dollars .

 

Retest fuel pressure. When it primes before starting, at idle and higher rpms, and whether it holds above 46 psi for 20 minutes after shutdown.