Turkey Day Help Needed!!! (e46 won't start)

My 2003 e46 threw a lean bank 1 code a while back and started idling rough so this is what I've done:

Found vacuum leak and replaced appropriate tubing (behind MAF to engine).

Replaced fuel filter with OEM filter (Hadn't been done in quite some time)

Replaced MAF with new OEM MAF

The car started hard a couple of days ago and the CEL came on. I popped the hood and checked all the connections and realized I hadn't retightened the battery terminal under the hood so I clamped that down but I have not had time to get the CEL read at AutoZone.

Tonight I came out of the grocery store and when I started it the idle was real rough and it died. I tried once more and it didn't stay started as long, even when I put my foot in it to try and urge it on.

When I swapped my fuel filter I removed the pump fuse and ran it until it died and I feel like when it died tonight it behaved very similarly to that. I tried to prime the line before I started it the second time and I could hear the pump working so I don't think it's the fuel pump.

I'm at a loss- I had to call someone and get a ride for myself, my 3 month old, and my wife and now I'm gonna bike back to the store and see if I can figure out what's wrong.

The car needs three things to start: fuel, air, spark. I'm wondering if my fuel filter could be clogged? It's brand new so it boggles my mind and I've driven at least 300 miles since I replaced it.

Any ideas?...

Oh, and Happy Thanksgiving!

Probably a sensor, but no telling without codes.

Yep....gotta get the codes read, otherwise you`re just stabbing in the dark.....

I'm gonna guess a vac leak from PCV or valve cover.

Update:

I went back to the parking lot today after and it started right up- I drove it home as fast as I could and got it in the garage and by the time I got it home (less than 5 miles) it was running rough again.

I'm trying to find an OBD II reader that I can plug into it and check the code(s) and I'll post more then but I still feel like it's a fuel issue. It runs when it's cold but then when it warms up it starts running rough again.

Any other thoughts?

OK, I went and bought and OBD II reader (probably should've done this long ago). The codes I'm getting are the same as previously:

PO171 CNF - Bank 1 System Too Lean

PO174 CNF - Bank 2 System Too Lean

PO171 PND - Bank 1 System Too Lean

PO174 PND - Bank 2 System Too Lean

What is the difference between the PND and CNF codes? Seems redundant but I guess maybe it's just the generic reader I bought.

I've seen this thread:
http://forum.e46fanatics.com/showthread.php?t=897616

And this one:
http://forum.e46fanatics.com/showthread.php?t=929501

And I'm starting to wonder if I might have made this problem worse when I replaced my fuel filter... There are lots of things I can continue to try but I don't want to keep throwing money and fix it with the very last thing I try. I am mechanically inclined but I don't know a ton about the car- I enjoy driving it and think it's fantastic when it works so I'm eager to track down the problem.

The only other thing I've done recently is replace the oil filter housing gasket which took care of most of the oil leaking I had previously but it doesn't make sense that this would have anything to do with my current troubles.

Any more thoughts for me? Thanks in advance for the help, I really appreciate it!

Anyone?...

Sounds like the same symptoms I had when fuel pump went out. Pump is easy to change, if it is this, get one from OEM Bimmerparts.

Is there any way to measure the pressure in the fuel lines?

Also another thing I noticed after changing the fuel filter is that my instant mpg gage is all screwy- it swings all the way to 12 mpg when I'm decelerating instead of staying on the 50 mpg side. Could this reflect a pressure problem in the vacuum hose off the fuel filter? As I understand it that vacuum line is one of the inputs the computer uses for the instant mpg gage.

Pump is getting power but I can't hear it so I guess it has to be the pump at this point.

The only other thought I had was that maybe that isn't enough power?

If you have not ever changed the pump, just change it. It is most likely the issue.

Matt, are you not getting 12v to the pump? check the fuse. I think there is a link on the wiki that shows what fuse powers what.

Originally Posted by CRJ900

Matt, are you not getting 12v to the pump? check the fuse. I think there is a link on the wiki that shows what fuse powers what.

No I'm not getting 12v, somewhere around 5v is what shows up. I checked the fuse and it looks good. Is there some other relay I should be replacing first before I order a fuel pump?

Found more information at this thread:

http://forum.e46fanatics.com/showthread.php?t=934787

Says I should only get 12v for a few seconds when the key is turned and I'm not so could this be a faulty relay? It seems to me that if the relay is faulty I wouldn't be getting the "supervisor voltage" to the pump...

Do not know what Scan Tool you are using, but I assume the PND reference is "Pending" which means the codes have not triggered the CEL light "YET". The other reference may be the codes triggered the CEL?

No issue making the problem worse by changing the fuel filter or pulling the pump fuse.

You likely were/are having a soft fail fuel pump that then hard failed due to the cold outside temps?? The fuel pump is a standard brush DC motor and when the brushes and commutator wear, the brushes do not make good contact.

A mallet to the bottom or top of the tank may "jar" the pump enough to start.

If your fuel gauge is around 1/4 tank, you should check the fuel tank levels with the Hidden OBC Menu and make sure the drivers side of the tank is empty. After about 1/2 tank, the drivers side should pump down to empty except under hard cornering, then it should pump down again. Fuel left in the drivers side is usually a sign of a soft failing fuel pump, low pressure & volume.

Fix the no start with a fuel pump, then worry about your Lean codes. The fuel pump may fix your lean codes, if not, check your CCV lower oil return line, intake boots and put your original MAF back on for a while.

There have been a lot of wrong MAF's showing up for some reason under reporting the airflow. I see you say you have an OEM MAF, where did you get it?? What brand is it??

Good luck.

I used the OBC menu and it says 076 161 for test 6.0

I'm assuming this to mean 7.6 on the left side of the tank and 16.1 on the right side of the tank? I have about 3/8 of a tank right now showing on the gauge so I'm guessing that it shouldn't all be on the passenger side yet.

I'm going to order the pump and a relay and replace both but I've found conflicting information about the relay location- is it behind the glovebox or under the hood on my car? Is this a generic relay I can get at AutoZone or another parts place or does it need to be OEM?

Relay is behind the glovebox. I would order a relay, if they can identify the correct part number, but the relay would be a when I get around to it task. You could try Autozone, but order your pump from BMAparts.com and add the relay to the order. With discount code and shipping you are looking at about $155?

Put a pump in it. I reuse the gaskets all the time, but you decide. Just make sure the pump gasket is installed in the tank on the lip. The old gasket will likely come out with the pump.

No need to order the relay. Just switch the horn relay and the fuel pump relay, unless the car has been garaged in NYC or Italy.

Sent from my MB865 using Bimmer App

We don't blow our horns in the city unless you drive a taxi.

Well I've ordered a pump and am now in waiting mode so since I don't have anything else to do and it's in the garage I adjusted my parking break, checked and cleaned my DISA, cleaned my ICV and then switched my horn and fuel pump relay just for kicks. I also ordered an oil level sending unit and have everything to change the oil when I get the part.

I'm still not seeing 12v to the pump at any point, even when I just turn the key to prime the pump (if it worked). I can't decide if this should concern me or not so I put it to you all- is there some other problem I should be trying to track down or is it normal to always see around 5v to the fuel pump?

Since you have already ordered the pump, I would say just install it and see if the car works properly. It is a 20 minute install except the time that it takes to take off that damned seal ring from top of the tank. If it does, don't worry about the 5V or 12V, but do keep us posted

I'd guess you need the 12V. Cannot imagine why you only have 5V.
Did you change or swap the gas pump relay to try?

Originally Posted by GoForthFast

I'd guess you need the 12V. Cannot imagine why you only have 5V.
Did you change or swap the gas pump relay to try?

Yeah I swapped the fuel pump relay with the horn relay and still didn't get 12v to the fuel pump wiring harness after the initial key turn. It doesn't really make sense to me that you would need the 12v to start the motor if the pump normally runs closer to 5v.

Perhaps the system uses the 12v to quickly pressurize the fuel rail and then once the system is up to pressure the voltage drops regardless of the vehicle having been started or not.

Though I'm thinking voltage correlates to electric pump speed which may be incorrect, I'm not very familiar with electric motors.

What else would control the voltage supply to the pump that could cause problems?

Originally Posted by Matt_N

Yeah I swapped the fuel pump relay with the horn relay and still didn't get 12v to the fuel pump wiring harness after the initial key turn. It doesn't really make sense to me that you would need the 12v to start the motor if the pump normally runs closer to 5v.

Perhaps the system uses the 12v to quickly pressurize the fuel rail and then once the system is up to pressure the voltage drops regardless of the vehicle having been started or not.

Though I'm thinking voltage correlates to electric pump speed which may be incorrect, I'm not very familiar with electric motors.

What else would control the voltage supply to the pump that could cause problems?

Lots of electrical components in modern engines run on 5V instead of 12V, don't know if the fuel pump is one of them. It sure sounds like you'll be all set with a new pump.

Honestly, I have seen the pump, and I see no reason why that little motor would need 12 V to run. I mean it could, but I would just put the new one in and then see if everything is fixed. You would need a new one anyway after all these years even if that is not the issue (I am 95% sure it is)

Fantastic news: my e46 is now running better than it has in quite a while. It started right up with the new fuel pump and I replaced the oil level sending unit and changed the oil, oil filter, and air filter while I had it on jack stands. Thank you guys for all your help, you no doubt helped save me lots of time chasing down my problem.

I've reset my SES light and now I'll wait to see if it throws more codes but it is idling under load significantly better than when I started chasing down the problem with vacuum leak fixes, fuel filter, and a new MAF. I also think cleaning my ICV and the buildup on my DISA probably helped. Ordered a new gasket for the DISA that I'll throw on when it gets here as well.

The only problem I do have is my MPG counter is still not quite right: the instant gauge swings to 0 when I come to a stop instead of heading toward 50 like it should. My average computed MPG also counts down rapidly when I'm stopped at a light but then when I'm driving it seems to be fairly accurate.

For example: when I reset it and then take off on the highway it'll jump up to about 20.0 MPG average but then as soon as I come to a stop it counts down 19.9, 19.8, 19.7, 19.6... and it does it fairly rapidly if I've just reset the counter.

I'm gonna fill up the tank and see if maybe that resets it. Anyone else encountered this or a thread somewhere with a similar problem? Overall the problem isn't exactly crushing to me since my car is now running like a champ.

Got a slight valve cover leak so I'm thinking it's time to swap the seals on the Vanos and replace the valve cover gasket next! I have a friend with a 330i and I'm trying to talk him into doing it with me so we can do his after (in considerably less time I hope).

Thanks again for your help all!

Oh yeah, plug for oembimmerparts.com: they got all my parts out the door on Monday afternoon in Texas and I received here in Oregon this afternoon and the prices seemed great for OEM.