Fuel delivery problems? 4.4 04
 

Hi! My 4.4i started acting weird around christmas. First i noticed that the engine would stall for a sec or so from time to time, and then suddenly it just wouldnt start a cold day (5F'). I got it starting once temperature was rising and with a can motor starter (would only ignite on that for a couple of tries), and once i got her running she was running poorly with misfires and wouldnt respond to the throttle for a couple of minutes. But after that she was running fine.

I took her to my garage and changed the fuel filter, in case it would be clogged. But didnt notice anymore problems 'til last week; i was about 1 mile from home when she started stalling and misbehaving. It took me a couple of restarts and some foul language getting home.

Today i started her up, and she's acting all weird again (i got a video that ill upload once i get home).

So; what do you think? No CEL and it only occurs sometimes. I figure it has something to do with the gas delivery since she would only respond and ignite on motor starter on christmas.

I can upload a tourqe report and a video later tonight.

Sounds like maybe the fuel pump. If you are near 1/4 tank, put 1/2 tank or more in it and see if the problem persists.

Never use motor start or starting fluid to start a fuel injected engine with a MAF. The MAF operate a hot wire or hot film and as air is passing through the MAF the computer can determine the amount of air passing through the MAF by the time it takes to cool the hot wire or film to a certain temp. The hot wire or film can be hot enough to ignite any motor start or starting fluid that is present in the MAF. This can damage the MAF, or cause a backfire that can start a fire in the engine compartment. Motor start or starting fluid is only advisable to be used on carburetted engines.

Read my thread on fuel system, if you are "running out of gas" when the tank reads 1/4 or 1/8 of a tank almost certainly it's the o-ring on the left side of the fuel tank.

The gas sprays out into the left tank rather than going into the siphon jet so the gas stays in the left side of the tank.

Use the hidden menu #6 to track the number of liters in the left and right tank.

If the left side is zero and the right side is 1.4 or so the pump is failing.

If the left side has 10-20L and the right side is less than 1.4L then the siphon jet is the problem and almost certainty the o-ring has failed on the siphon jet and you can fix for free with a few wraps of Teflon tape and some zip ties.

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Every siphon jet I've ever worked on over 120,000 miles has had this failure, it's a design defect and you can expect every BMW with this style of siphon jet to have this problem about 130-150,000 miles.

The problem will bite you in the ass if you don't periodically run your gas down to the low fuel light or even single digits distance to empty..

Yes, i checked the numbers in the hidden menu; 34,5/5,4L. So you seems to be right. I´ll take care of it this week. Thanks alot.

Yes, i was aware of that, but i was getting desperate. Buit thanks for the heads up.

Fuel delivery problems? 4.4 04
 

surely a leaky connection at the siphon jet.

If you have a digital caliper (heck of you don't get one) measure the size of the opening vs the o-ring then the o-ring in the groove.

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Here was my inside diameter, fixed outside with Teflon above.

I disassembled in place so I didn't have to remove the actual siphon jets from the car.

There is a second seam that does not have a real seal, test for leaks by reassembling and put the sender unit mostly in and turn the key to on where it primes the fuel system

If that seam also leaks, take apart wrap with Teflon until the fit is tight radially and put a hose clamp around it

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And the fix for the design defect.

Install a nylon zip tie as shown. It will force the fitting up tight as opposed to the factory design which does not. Think about it: where have you ever seen any o-ring connection that we held only from the side where soft plastic was involved and it's holding high pressure? Moron Engineer came up with that. If they had just included a bump to push out on that left post so the right one acted like a fulcrum it would have literally saved owners MILLIONS of dollars!

Think about how many 14/20 year old cars were towed, had expensive stealer estimate more expensive replacement of a perfectly fine part with a leaky 30¢ o-ring!

I bet the average total cost per owner of this failure is about $500-700. For you thanks to xoutpost, 1-2 hours of your time and pennies of tape (and perhaps $20 for a digital caliper)

So: i brought her to a makeshift garage (a parking lot). I miss my garage.... and removed the engine cover and checked the fuel rail valve, no fuel there. So i removed the fuel pump and i tested in up in the air, it's not running at all..... im gonna get a multimeter tomorrow and find the problem. Either if its the pump, relay or cable harness.

On top of that i also got this siphon jet problem andrewwyn spoke about. Im also checking that out tomorrow.

A soft fail pump will also cause the siphon jet problem. If not enough pressure generated not enough pressure left to operate the siphon jet.

I've never personally witnessed a pump relay failure. If the pump's not spinning my bet is on the actual pump.

Measure voltage going into the pump. If 12ish pump is shot.

You should check the o-ring on the siphon jet at the same time since the failure is visible it doesn't need to be running.

Wondering how you got to the parking lot with zero psi fuel

Made some progress today; nothing wrong with the siphon sealings, the fuel pump is in order, the relay is clicking and there is current right after the relay in the socket, but there is no juice at the pump. So i measured the resistance in the positive cable but it was fine. So then i found out there is no juice on the connector on the fuse box....

I'll dismantle the fuse box tomorrow when i have some spare time.

I towed on a flatbed

You need to measure voltage to some other ground it could be there ground is a problem also. Find voltage to the pump and make sure the pump spins?


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