I haven't had to add any coolant in the year and a half I've owned the car. I went out and bought a bottle of Prestone just incase but haven't had to crack the bottle at all.

After watching some of the horrors of a cracked head gasket or it just being brittle after so many hundreds of miles... I've considered replacing it as preventative maintenance but haven't had the need to yet.

I have noticed some use of oil though.. which is one of the only gaskets I haven't replaced is the oil pan... which is a TON of work, but it might be on the table if this all debacle doesn't go away...

On the YouTube I also found this playlist of videos for various repairs on the E53... well worth checking out from AutoDoc.

Example of a fuel pump.
https://youtu.be/gKkml7AMJ64

On a side note it did occur to me that I also replaced the fuel pump when I first got the car, after putting UV dye in the tank to check for any leaks. I've used it for oil and coolant, so I thought why not gas? Which I never saw any UV fluid at all.. which means more than likely my fuel filter did it's job and I probably killed it.

Which could be an issue, but this has gone on for as long as I have owned the car.

Fuel filter is ginormous on x5. It should last half a million miles as a filter. The fuel pressure regulator is more likely to fail but should last a quarter million miles.

Reading hundreds of threads on fuel system repairs on BMW I've seen in every case that when the fuel filter was considered as a fail point and replaced that eventually the real fault (usually the siphon jet or the electric fuel pump).

If fuel pressure at the rail waivers more than 1 psi time to figure out where the lies.

If the fuel pump is over 4000 hours old it's the most likely candidate.


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*EDIT - It has the factory fuel filter on it, just rolled over 251k miles last month.

I figured getting a fuel pressure regulator down the line as part of the "next on the list" should the current parts on order not work out. On BAVAuto... they only have Fuel Filter / Fuel Regulator Combos... which the Genuine BMW and MANN both have the same part number and serial number on the side. So... maybe they're the same with a 70$ price difference? Would you care to look at the links and tell me what you think?

https://www.bavauto.com/bmw-fuel-filter-wk532

https://www.bavauto.com/bmw-fuel-filter-13321709535

As of my initial purchase of the car the fuel pump was replaced with Genuine BMW parts, placing it down inside the tank was a chore, with that double lipped sealing gasket but once my level lock ring came in from Amazon it was easy peasy.... but this is first I am hearing of this siphon jet. I will have to do some research on it. Any pro-tips for testing it?

AndrewWynn is the expert on the siphon pump, but ...

tell me if I'm wrong, but I think if you keep your gas tank FULL and the problem persists, it would rule out the siphon pump being the cause of this problem. I'm lazy, so I always look for troubleshooting that does not actually involve any work. Not that this test would rule out any problems with your siphon pump - it just effectively removes it from the situation, while your tank is full.

Ah, well I’ve teated that a number of times. It does happen with a full tank.
Perhaps we can still get his input on it...

To Misfire or not?
 

• FPR not 10% as likely a low fuel pressure problem as a worn fuel pump (brushes) carbon apparently is slightly soluble in pure gas. Exoect 3000-4000 hours with pure gas, 5000-6000 hours with 10% ethanol
• siphon jet has zero effect leaky or not until the total fuel level is about 30 liters.
• "the problems" you were describing sound like CPS or spark plugs/coil problems. Since CPS is waaaaay overdue and plugs already swapped, next logical step is CPS then swap coil packs is problem persists but parallel check: test rail fuel pressure.
• test for siphon jet failure is simple: put a can of gas in your trunk and drive down to a DTE of a couple miles. With OEM pump/sender you have about 10-15 miles left when the DTE reads zero (3.6L when I measured to the gram the amount of fuel I siphoned from the tank at 0.0dte in my wife's car)


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There was an odd occurrence a little while ago which led to the replacement of the fuel pump... I was on the highway going 65MPH, all of a sudden the RPMS started dropping, throttle unresponsive, RPM dropped until the car died and I had to coast to the side of the road and put on my hazards. It gave an error which I can't remember for the life of me... but all signs pointed to it being DEAD. But swapping the fuel pump got it up and going again.

Just did some searching through my Internet History... (Scary right?)
April 4th, 2018 - So I guess it wasn't right when I bought the car, but sometime after the fact. I searched for 2002 BMW X5 3.0i -- TRANS FAILSAFE PROG

Which at that point it wouldn't turn over at all. I was able to add more gas and it started up.

Would that indicate an issue with the fuel jet siphon?

*EDIT
The pump that I changed out was on the passenger side. Is there another one on the drivers side? I put a brand new BMW Genuine Fuel Pump on it.

To Misfire or not?
 

By passenger you mean starboard (this forum has lots of people with RHD cars). Anyhow yes the electric fuel pump is on the starboard side and there is a siphon pump on the left hand side (port) side that uses excess fuel volume returning from the fuel pressure regulator to suck the fuel from the port side lobe of the tank into the 5L dent on the right/starboard side where the electric fuel pump is.

Quite a lot of fuel goes around and around in circles much more than is actually consumed so when the siphon jet fails (they all will due to a design flaw) it does not take long before you starve of fuel with a reported 1/4 of a tank of fuel.

A trans failsafe that clears itself is voltage related (which can happen from a stall when running).

I'm not sure what problem you are trying to solve at the moment. If you "ran out of gas" with about 1/4 tank it's at least 90% chance your o-ring blew out of your siphon jet: replace the o-ring and put a nylon zip tie in the right place to cure that problem for nearly free.

If you do take it apart and get the o-ring out report back the size: I wrote the book on that DIY repair and forgot to measure the size of the o-ring

Oh Okay. I didn't know that. If standing behind the vehicle, the electric pump I replaced was on the right side. This is link to what I used.

https://www.bavauto.com/bmw-fuel-pump-16116755043

I didn't realize that... Will keep that in mind though, especially because it has "Ran out of Gas" at 1/4 tank several times. Thankfully I was only caused to walk in the rain one time to get gas. I keep it above 3/4 tank now.

That makes sense and seems exactly what happened.

Would this also possibly produce a gas smell on the (from the rear of the vehicle looking forward) left hand side due to that O Ring not being as it should be?

I'll probably go ahead and check this out when I get these parts in so I don't have it inoperable for so long. The Wife's 04' CRV laid down on us recently after 212k miles so this X5 has become the primary means of transport.

In regards to the O-Ring, I found your thread and bookmarked it for later reference.
In this diagram on RealOEM, is it the number 4?

https://www.realoem.com/bmw/enUS/sho...diagId=16_0460

Part #
16116761645

https://www.bavauto.com/bmw-16116761645

Holy crap yes that o-ring. 22x2mm. I think that is the ID (22). You don't have to use a BMW official part of you can find a normal o-ring at a local shop.

Will not cause smell from the o-ring leak it just spills Into the tank.

If you "ran out of gas" more than once at 1/4 tank you definitely have siphon jet leak and almost certainly at that o-ring.

The gas spills from gravity to the right tank down to about 1/3 and people who knew they had the problem have been able to avoid a tow with a sharp left turn which will slosh a gallon of gas into the pump out as they were about to stall. No need to keep more than 1/3 of a tank to avoid the siphon jet issue


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