Ah I did wonder what you were on about!


And yea mine died before getting to that test, we were just moving it off the brake checking machine when it conked. Highly annoying but the tester is a really good guy and messed around for 5 mins and checked the pump and confirmed it died for no extra charge.


Nice to have helpful staff, he'll be getting a xmas 6 pack!

We saw it was the other car but it’s a relatable circumstance.

My wife’s FP died one day we got home and wife wanted me to move the car a few feet to not block the walkway. Wouldn’t restart. Best timing ever to fail.

I got stranded a few times from the siphon jet failure (before learning what the hell was going on).

You said the hose was busted?

The hose has to work or the pump will move all the fuel to the left tank. Have you monitored the fuel tank levels while driving? The hose can be leaking to cause inefficient transfer left to right would give the same symptoms of jet pump leaking.


–awr–

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It's the siphon jet that's failed *presumably - Fuels being pumped to the other side of the tank which is causing the issue so I need to keep it above a certain point or it conks out. I think the secondary pump is taking up the slack.


I used the normal dash test to watch levels on the tanks and it all fits with previous posts about the siphon pump.


Other then shoddy MPG of 23.7 I'm not noticing any other fueling issues. I did have a minor leak at the HPFP but I replaced that hose with a new one from BMW so thats all solved now

The jet pump is usually repairable. There’s a design defect that makes them spray fuel out the side as the plastic part bends over time both our e53 had exactly the same failure and I’ve seen many similar on the forums.

Usually just replace the o-ring and some Teflon[emoji769] tape.

Looks like e53 siphon jet shares some dna with the e36. (Similar connector from the level sensor going down to the feet of the siphons). I’m betting same failure mode similar repair.

The first time I got stranded WA’s because wife never told me she needed to get rescued with a can of gas when the car showed ¼ tank. She just never went below ¼ after that but didn’t tell me.

So when it happened to me it was the start of my learning curve.


–awr–

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Good shout, I'll dig the pipe out when I get the car back and take a look. Hopefully its that easy! Its not a huge bug bear but it's annoying.


I miss driving on the edge of the red line :D


But with diesel prices I may swap back to E36 longer term to save on fuel!

The ¼ tank failure mode is almost always from the o-ring leaking going down to the siphon jets. It just makes the siphons weaker so they need doin some amount of fuel at the bottom of the tank to function.

If they didn’t work at all, the fuel would all stay on the left tank until it can flood over to the right. That happens at about 27L on E53, not sure when in E36.

The positive confirmation on e53 is the right tank will read a constant 1.4L of fuel steady state driving once you get below about 27L but at ≈ ¼ tank the 1.4L will start dropping to zero. You only have a few minutes/miles if that happens. When right tank reads zero there’s about 1 gallon left but your can’t drive 15-20 miles as the fuel pump will be pushing fuel to the left tank.


–awr–

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Yep thats what happens to me, get to a certain point and it dumps all the fuel over the other side.


I'll check that at the weekend, do you happen to remember what size O-Ring it was?


Something you may be able to shed some light on, I have in the boot on the left hand side looking in - Where the amp usually is, it's always wet and I have no idea where it's coming from. The light seals are brand new and fully sealed. I threw a air line over it and nothing came through.


I can't think of any other obvious places it could be coming from. Underside is fine and all the plugs are in place, I considered the roof strips which there was a small crack but that turned out to just be the paint.

Its not the washer as thats been disconnected for a long time. So I'm a little stumped

My e70 gets mystery water same location I don’t check often enough to figure out the source. I drilled a drain hole and it apparently collects slow enough no more puddle. My guess was spray from wheel but I haven’t had a chance to root that one out.

https://chatgpt.com/share/69b0351b-b...1-890b0c77c09c

GPT found an answer on the o-ring in your case. BMW doesn’t list the size but 7.5x1.5 is what GPT came up with.

That’s way way smaller than e53 so it’s less likely the fault. More likely if like e53, there’s a plastic to plastic flare fitting with no seal just plastic to plastic that’s where I put Teflon[emoji769] tape.

Find my awr-fix on the siphon jet to compare.

The connector seems similar from the BMW shop manual and if it’s held together just from one side I’m pretty confident it’s a similar problem with a similar fix.


–awr–

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E36 Is back on the road, so I have wheels to now deal with the E53!

Will attempt a fix at the weekend... then figure out how to get both cars home :D


Ill let you know if the TCC&2/3 Solenoids fix the issue