To confirm o-ring failure open up the left side and lift it just a little bit. Wrap with shop rags you can burn if gas sprays and just turn the key to on.

The pump will prime and send fuel back to the siphon. If the o-ring has failed it will spray sideways.

(And directly into your iphone if you happen to be recording to shown to others).

If you pull out the sender unit it's usually quite obvious when the o-ring has failed it will be pushed out of its groove.

Some times the o-ring itself will fail and leak without visible clue though so the only way to be sure is key on while observing.

You can be 99% sure just from reading test six.

When total fuel is below twenty eight liters, the right side should stay at ab9ut one point four liters. If it drops to zero the siphon pump is not working. Almost always from o-ring failure but can also be from the electric pump end of life so it's not one hundred percent.

[mention]kfm [/mention] which foxwell are you using? Only the 500 and 700 series are useful the others are just like generic.

510 and 710 are the ones I have and they are very good. Mostly because they are bi-directional and have solid BMW modules.


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OP's other thread is on BimmerFest
 

In his parallel thread on BimmerFest, the OP stated he was using a Foxwell NT530, and didn't trust it. I have no experience with the 530, so I can't comment on it, but my NT510 Elite has done all I've wanted from it, and it's paid for itself many times over.

530 should work very much the same but it's non intuitive and there is a learning curve.

In my case, the o-ring didn't blow out. If fact, from outside, it looked perfectly seated in its grove and the two parts that holds the o-ring has no misalignment in angle. Except the o-ring was broken, which became obvious when I separated the two parts. I didn't realize I could test it to confirm it was bad. But I am pretty sure no way that o-ring could have kept the fuel inside. After repairing, - just got my o-ring delivered - I will test.

I have indeed the NT530. My problem is that it give "No Communication" when trying to test the engine and transmission ECUs. And quick scan tells me no error code found.

Also, it took forever, like > 5 minutes, to get VIN, establish communion, downloading info, before I could do any useful diag action when it worked.

Ah, sorry, it was a convoluted story, I dropped some details in between the events. What happened was that after it was towed back home and parked on the driveway which has a decent slop, I could start the car again. I didn't want to risk driving it but also didn't want to leave it out of the garage because rats will at first opportunity get into the engine compartment! I saw rat dropping in there from just that one night outside. So I drove the car back into the garage. But then it stopped runing again. Altogether it run may be 5 mins.

I speculate what happened was that when we loaded the car onto the flatbed tow truck, the car was serious titled front up. When it was parked on the drive way, it was front down. These inclination changes must have sloshed fuels from the sender side to the pump side, allowed me to run it again briefly.

But now the pump side was empty again. Until I put in more gas following CN90 post.

So my question was meant to confirm, when I couldn't start, i.e., no fuel in the pump side, then trying to start the car won't see fuel coming out of bad o-ring. I believe based on all the additional postings here, this is indeed the case.

Typically from low voltage will have a problem with communication. It's recommended to be on a battery tender but they should usually work.

When it won't scan the VIN try manually enter or use a saved scan to start.

Also some contact cleaner can help or the problem can be a damaged OBD port.

higher voltage, better scans?
 

Yep, my NT510 Elite is also definitely slow, but actually speeds up a bit when fed with more voltage, when I use the "stable power supply" feature on my "Clore Automotive PL2320 20-Amp Fully-Automatic Smart Charger" on power supply mode. It even seems to find more modules on quick scan than it does when on battery alone, if at 12.5v or less.

Someday, I'm gonna get the NT710, which is surely faster.

Lifting onto a tow truck almost certainly sloshed some gas to the right lobe of the tank.

It won't last long as more fuel is sent to the left side than is consumed by the car.

When i tested mine to confirm leaking, I was expecting fast dribble but i got garden hose right into the lens of my iphone. Definitely put shop rags around the opening when you do this test.

It's interesting to see age killing the o-ring itself vs. the joint bending.

I was actual on battery tender.

It is not that it wont' scan the VIN, just that it takes at least 2 mins (although I didn't precisely time it) for that part of the start up. It does reads the VIN correctly.

The generic scannere works no problem, so it shouldn't be OBD port problem.

I will need to take it up with Foxwell on this problem. The last time I used the scanner about two years ago, it gave a bunch of error codes related heater, AC, and something else. Although the heater and AC were all working fine. I wonder if the scanner may have already been going bad.