Fuel pump and pressure question

[Henn28]

Hoping to get some clarity on what else I might need to change, if anything, when I put a new fuel pump in. I’m struggling to find the great write up I read previously on this topic so I apologize for coverings ground that has been covered before.

I’m on the second pump in my E53. This one went in in 2007 and has about 80k miles on it. I’ve noticed a stumble on hot starts where the car needs a bit more cranking than normal to catch, or it stutters a bit when it does start. Once running it seems fine, and cold starts are always fine.

I have a new Delphi pump I was going to put in when I swapped the motor, but ran out of time. I’m planning on dropping it in soon and I also finally broke down and bought a pressure gauge/tester:
- 50 psi on the battery
-43ish with the motor running
-loosing about 2psi every 20 seconds or so

The first two seem normal according to my Bentley manual, but the pressure loss with the key “off” doesn’t and might explain the odd hot start behavior.

I have the early fuel filter without the pressure regulator, so my question is: will a fuel pump fix the pressure loss and if not, what else should I replace while I’ve got the seat out? Is there a separate regulator somewhere to keep the pressure from dropping and which should be changed on the 2002 and earlier builds?

Thanks all

[crystalworks]

You check your injectors for leaking when you did the motor swap?

Man, the separate fuel pressure regulator for that is not cheap. https://www.fcpeuro.com/products/bmw...or-13531436110

[80stech]

Can you not use the filter with the more built in regulator ??

[Henn28]

Thanks for the replies gents.

****Update
So the FCP fuel pressure regulator listed is for the later fuel filter that doesn't fit my car. 16126754016 is the one that does fit and it does not have a replaceable regulator. Although RealOEM lists it as a "fuel filter with pressure regulator". I have read elsewhere that these (much smaller) filters don't have a regulator function. Curious.
******

I don't think that the injector(s) are leaking because I had them cleaned, leak checked, and flow tested when I was putting the motor together by a place in Houston that specializes in such things. Just like my kids, they came home with a report card. The report on the injectors was glowing - everything within BoschBMW OEM specs. Thats not to say that something hasn't gone south though. The entire intake assembly is from ebay as I wanted the long runner intake and still have dreams of rebuilding my 4.4 so I didn't want to cannibalize it totally.

The only reason I know there are two different fuel filters (early and later models) is because the first one I ordered to swap out during my build didn't fit. It was the later model, wtih the regulator integrated into it and the fittings don't match at all.

Yep, $150ish sucks for sure for such a small part, but probably worth doing. Just need to dig into RealOEM and sort out where it goes. I didn't find it when doing my homework on this issue yesterday.

My plan then is to put the new fuel pump in, replace the o-ring on the other side per many great discussions on this forum, and R&R the regulator.

[Happy]

https://www.fcpeuro.com/products/bmw...709535#fitment

This is the one my pre Feb. 02 uses.

[Happy]

Originally Posted by crystalworks

Man, the separate fuel pressure regulator for that is not cheap.

I do not understand why the regulator by itself, cost more than filter and regulator combined.

The regulator you posted is the same one installed on the filter I posted.

[Henn28]

This is my fuel filter: https://www.fcpeuro.com/Parts/?keywords=16126754016

No integrated regulator on it. I think they cut over shortly after mine was produced in June of 2002.

I’m just guessing that there is a simple valve on the pump that is supposed to keep the pressure in the system.

[Happy]

February, 2002 changes were made to the original form. My build (01/2002), was the last month they were built completely in original form. Thereafter changes were made.

There seems to be some discrepancies with the dates though. But from my experience, (02/2002-2006) E53’s have some subtle, to substantial changes. You should be fine with your (06/2002) build. The dates in question are Feb. and Mar.

Anyhow, it appears that the part number for your build does come with a pressure regulator. They have it at (04/2002-2006). I’ll post the link below, I hope it helps.

https://www.turnermotorsport.com/p-2...is-42000-2006/

[crystalworks]

I thought I remembered you having someone in Htown go through your injectors before install. Just thought I would mention it.

At least you're saving some money with 16126754016 . I went with an early model diagram on RealOEM and chose the one with separate FPR per your first post which I read incorrectly. As Happy mentioned, the FPR is supposed to be built into the style of filter that yours needs.

Originally Posted by Happy

I do not understand why the regulator by itself, cost more than filter and regulator combined.

The regulator you posted is the same one installed on the filter I posted.

That's BMW for you. Interesting that they had 3 different iterations of the filter/FPR setup.

[Henn28]

My fuel filter is only six months old or so. There is a definite possibility that it’s a bad part then. I’ll swap the new pump in and test the pressures. If it’s still leaking down then it must be the filter. I’m not smelling any gas at all around the car so I doubt a leak elsewhere.

Thanks all