E46 fuel relay, filter, or pump

[rlanzone1]

Interesting issue, trying to isolate exact root cause.

2004 330i SMG sedan Sport Package with 50 K miles

Car failed to start in am, found blown 54 fuse 20A for fuel pump.
Replace fuse, car started. Car starts all day long no issues regardless of # of times.
In the am only, car does not start. For 3 of 4 attempts performed the following:
After 2 to 3 attempts to start, pulled fuse to see if blown, was not blown, reinsert fuse and car starts and runs fine all day as before.
On one attempt did not pull fuse but car started on 3rd or 4th attempt.

Root cause potential 1.
Fuel filter as can suppose a restricted filter is root cause as when car sits for 10 hours the pressure is reduced and upon am startup, it take a few attempts to repressure past fuel filter restriction

Root cause potential 2.
Fuel Relay is bad and pulling / reinserting the fuse resets the relay, then fine throughout day. Not sure why this would be time dependant (?) thoughts. Relay is cheap but located behind glove box.

Root cause potential 3.
Fuel Pump / sender bad and overnight with loss of pressurization, fuel pump not bringing up pressure until multiple attempts / cycles. Once pressurized, no issues with restart as long as not too long duration without starting.

Therefore I plan to do the fuel filter (good maintainance item), then the relay (inexpensive), then eventually the pump / sender. ($ 280 parts).

Was advised be BMW and indy BMW mech that it is the pump. They also advise to replace pump and sender at same time as sender goes bad first then the pump.

Interested to hear opinions on root cause. I am an engineer by trade and root cause analysis is part of my professional business.

Will advise my findings - Thanks

[rlanzone1]

Update for post, this am removed fuel pump fuse and reinserted prior to morning start up attempt.

Car did not start again, until 3rd start attempt. Therefore removal and reinsertion of the fuel pump fuse is a red herring.

Therefore my assumption is pressure related vs. electrical although the fuel pump itself could still be bad.

Next item is to replace filter which should be received in a day from Pelican, then the relay.

[Manolito]

You don't mention whether you can hear the pump spin up for a second when you turn the key on. That is a key piece of information.

The hose clamps on the fuel filter are designed to be single-use. Did you order new ones?

You don't need them, but here are instructions for replacing the fuel filter:
Cabin_Filter
(sorry about that link name, I have some typos in the HTML code on my web page that I need to clean up)

[rlanzone1]

Thanks - I did not know they were designed for single use. I did not do the job yet so I will go get some new clamps from BMW.

I can not hear the pump spin up, I think it is too quiet. Basically every am takes e to 4 start attempts then once starts up you can start it all day long. I am leaning towards restricted or clogged fuel filter as root cause. Will keep posting. Should get the parts today. Thanks

[JhwShark]

Not sure about the am thing; however if it is cold in the am, a weak Bat would/could not provide sufficient energy to start. Check Bat off and run and Alt output.

On some models & makes, due to high press Fuel systems the car needs to be switched on to charge up the pressure in the fuel system a few seconds before turning to Start. As you have ?'nd Fuel system check the components with suitable troubleshooting routine; someone point to any references would be helpful.

Try jumping the FP relay socket to get the pump to spin. Pin socket 30 (Hot) to 87 (path) in most German rigs. Since you are an Eng find the current or wiring diagram to determine possible circuits as well as.

Jon

[rlanzone1]

The only way I will know for sure if it spins up in the am, is to remove seat and housing during the am startups. I can do this over the weekend but weeksdays too busy.

Typo before 3 to 4 attempts, hit e instead of 3.

[rlanzone1]

Thanks Jhwshark, it is not Temp issue. I am Phoenix AZ and the coldest it gets in the am is just mid high 50's more like 60.

Thanks for details on electricals.

[rlanzone1]

Also Battery is strong, no slow cranking at all.

[Manolito]

Re: Picking up hose clamps at the dealer - a bit off topic and not important for this job, but I recently bought BMW hose clamps on line to use on power steering hoses on an e36. I was impressed with how round, smooth, and strong they were. When I did the PS hoses on my other e36 a few weeks later, I ran short of clamps so I picked up a couple at the dealer.

I paid 3x what I had paid on line.

Both clamps stripped when I tightened them.

I looked at them carefully, and although they appeared to be the same design, the ones I got from the dealer were not BMW branded clamps.

Gotta be careful these days.

[JhwShark]

Do you lose any performance at higher rpm's??...this could indicate cloged/gummed Filter.
How long have you had the car and when did this start occuring (and after any/what work?)?
It seems that the FP relay is good since the car runs. You just have challenge starting in the morning (or after a period of not using the car; i.e.: overnight or longer) and not temp related.

I am leaning to the system pressure waining, as you believe is a could be. In tomorrow am before getting to the Start on the ig switch turn it to ON wait a few seconds, turn off repeat a couple of times, then just go to Start. This can tell you if you are pressurizing the system. and/or to look for any leaks...fuel accumulator??
Jon

[rlanzone1]

Thanks all, went to BMW they do not even have hose clamps and said they are regular clamps. So I will see when I change the filter.

I picked up the FP relay for $18 (behind glove) as even Pelican says before buying a Fuel Pump to change the relay first.

This am I tried the ignition B position on and off a few times before start attempt, did not make a difference. It started on 3rd attempt, this time sputtered a little when it started, before always ran fine when started.

I am still thinking there is a filter restriction that takes a few FP cycle pressurizartion attemts to overcome. This issue began this past weekend.

So first the filter, see if happens in am, then the relay, see if happens in am and will advise - Thanks again.

PS. Once running everything is perfect, great power, no rpms moving around, nothing at all.

[JhwShark]

IMHO...The dealer is not always the most knoweldgeable. They sell and service according to protocol.

EFI cars typically require better than standard hose clamps for in-line faastening. The main reason we do not like to use standard hose clamps is that they can, in lots of cases, not fully secure the hose to the fitting. Those open segments throughout the clamp (which allow the screw tightening mechanisim to screw it tight) can provide flex to the hose and compromise fuel pressure. A lot of people use them, if at all possible get the right type of hose clamp.

It does seem to be pointing to something compromising fuel pressure???

adding: some models/makes have an in-line mesh filter in the intake part of the FP. Check your pump diagram for this element. It would be able to be pulled out and simply cleaned by removing the line. I had this problem on a 2002 years ago, though it was a mechanical pump.

[rlanzone1]

Ok, here is the final root cause. Ran out of time to repair with parts on order as needed to travel this week. Therefore brought to my Indy Mechanic.

Pump getting electrical power on start-up but fuel pressure low. Pump overamps trying to build up pressure and can blow fuse which it did again recently.

Pump is bad and being replaced along with Sender unit as Indy mechanic and BMW advised need to do both when replacing Pump. Of course changing Fuel Filter as same time which is advised.

Thanks all for support.

[330ci 2002]

Hey rlanzone1,

Just wondering who you are using as your Indy shop in the Phoenix area and if you would recommend them. I'm in Chandler and have 1 shop I use occasionally but would like to have another trusted option.