The mystery deepens....Hall sensor etc

[Canyon Runner]

All,

Hello!

First, by way of review:

Bike cut out at 65-70 miles an hor on a ride. Coasted it over to the side of the road. No restart on reattempt, no obvious fluids or leaks, or odors.

No symptoms leading up to failure.

Towed to a dealer.

Diagnostics indicate bad hall effect sensor. OK. Replaced.

Tech reports that Hall sensor now showing green light all the way around.

BUT... no fuel pressure, at all.

They are theorizing that the failure of the hall effect sensor at speed might have created enough back pressure to have blown off a fuel line.

Sound possible/ probable? Possible altenate theories?

Any input appreciated.

2005 R1150R

Cheers!

[iowabeakster]

The bike is still at the dealer?

So you can't say what sounds the fuel pump is making...

I suppose the good news is that if the hose theory is correct, it shouldn't be too expensive (above the cost of the HES).

[sweatmark]

They are theorizing that the failure of the hall effect sensor at speed might have created enough back pressure to have blown off a fuel line.

Interesting theory.

Have to call BS on that one, will gladly eat humble pie should the theory turn out to be true.

My first guess is electrical problem. Broken wire, relay fault, something like that.

[Canyon Runner]

The tech reports all "normal" sounds with respect to the fuel pump/ starting process. Key turns, everything sounds OK, but just no fuel pressure build up at all. In the interest of full disclosure, I was talking to the service manager fronting for the tech. That description of the audible clues (or lack thereof), however, matches my subjective experience after the failure, when I tried on a couple occasions to restart.

I think I am going to try and lean in and learn a bit on picking the bike up, however. Just don't want to bleed unnecessarily. Unfortunately, I am an apartment dweller with no real work area/ tool set up, so I am a bit beholden to the shop for their expertise (although I am slowly trying to rectify that by taking on the little things in my grasp), but this one feels beyond my current depth. And, as these things inevitably go, the part and labor to replace the Hall sensor are covered under a warranty I bought for the bike, but the diagnostic time to figure out what it was, and the diagnostic time to figure out why the Hall sensor did not solve the issue, are on my dime.

(sigh)

I think this might be Robert Persig telling me that I need to become more handy with a wrench.

Cheers!

PS... Sweatmark... your mention of a wiring and/or relay scenario is concerning, yet intriguing. I'll keep you posted. Thanks for being willing to thoerize on my (I am sure) woefully incomplete technical descriptions. I really appreciate all the knowledge on this board!

[jcridge]

What does the dealer charge for replacing the fuel filter? While their there "changing the fuel filter" they can discover or not if the fuel pump line is disconnected.

The fuel pressure regulator controls pressure, that's not in the tank. If you clamp the return line, do you have fuel pressure?

99% of all fuel related problems are electrical...Lucas

John

[CNorris]

I've been following this to see where it ended up since it reminded me of a problem I had a few years ago. It turned out to be spark plug wires. Never thought of it. Went through all the stuff you're doing (to the tune of $475) before a tech thought to check the wires. I think they were around $80. At the very least, check 'em to cross off your list. Good luck!

[Canyon Runner]

So, unless there is sleight of hand afoot, which I have no reason to suspect, the theory of the BMW techs was confirmed. They called to let me know the bike is ready for pick up and that the fuel lines were indeed the culprit, as they had become disconnected. Since they were obviously connected just before the failure (as the failure happened under power at 65 miles an hour), it seems a logical assumption that the fuel lines were disconnected as a function of backpressure from the Hall sensor failure.

I'll know more when I get out there Saturday to pick the bike up, but my extended warranty at least downgraded this from a brass knuckle gut punch to a good hard open handed smack. Strange days when I am happy (in a weird way) for a smack in the face.

The irony is that I had literally just cut the check to pay off the bike the day before I went on this ride. Hopefully, she is done giving me surprises for a bit...

Cheers to all that contributed. I will post one more follow up once she is back in my hands.

[CycleRob]

So, it was the external fuel line QD that caused your flame-out. Replacing the HES was a waste of time and money.

This is an important lesson for our "rider's memory toolbag". The QD looks like it is together, but when the tab latch gets accidentally depressed or it wasn't completely latched in the first place, it will be pushed apart by the fuel pressure. As you should know, the stock BMW QD's are "dry break" fittings, meaning an internal check valve closes when the two halves are separated and fuel flow stops. It doesn't take much of a separation distance for this to happen. Then the engine will not start or run.

I always recommend when diagnosing a problem to make the easy shots first. The QD connection integrity should be first or second on that engine stall out list. Blowing an internal fuel line open (or blowing it off it's fitting) is another possibility.

.

[iowabeakster]

Replacing the HES was a waste of time and money.

I wonder if the HES was bad and did need replacement... and tech just didn't get the QD pushed all the way together when putting the tank back on. We'll probably never know at this point.

[sweatmark]

I wonder if the HES was bad and did need replacement... and tech just didn't get the QD pushed all the way together when putting the tank back on.

Now that's a theory I can buy into.

I still call BS on notion that Hall effect sensor failure would impact fuel pump/connectors/pressure regulator while underway. The fuel delivery system is physically isolated from other bike systems. A partially-engaged fuel line quick connect would more likely fail during startup as fuel pump quickly increases line pressure from 0 to 3+ bar; that same quick connect is not going to care if the Motronic suddenly shuts down fuel injector trigger signals and the mechanical fuel pressure regulator reacts to a bypass flow increase that's some small percentage of normal conditions.

[iowabeakster]

My first reaction was...backpressure?? (huh??)...created from what??...into the fuel lines how??...where the heck was pressure regulator during all of this???

I really, really, hate when mechanics give BS explanations. I left my old car mechainc after some such BS. I could tell the second I asked him about the problem that he didn't even look into it, as requested. I gave him the benefit of the doubt. Of course, the problem was still there. I had to bring it back. Some people can be fed a BS excuse, others just might have a clue.

Don't lie to your customers...

[jcridge]

Being a flat rate mechanic for 25 years, I can tell you from experience that the initial problem was most likely the HES. Putting the tank back on after the diagnosis and not full seating the QD's was a OS moment. Not realizing it and spending too much time chasing it, then finally discovering it on his own, or having another set of eyes looking at it, is all normal shop learning experiences. But charging the customer over and above is not a good practice. Does the HES and or wiring go bad, yep... so at least you have one of the typical failure items checked off. Stick coils are next

John

[CycleRob]

"They called to let me know the bike is ready for pick up and that the fuel lines were indeed the culprit, as they had become disconnected".

The tight area where the QD's are makes it possible for "something" touching the metal tab to push it in and release the QD latch.

I get the opposite of TMI on this one, NEI (NotEnoughInformation).
Are they talking about the internal fuel lines, like the one's attaching to the internal fuel filter? A rider replaced fuel filter with clamps not properly tightened could see a line blow off the fitting even months later. Also, a QD fitting that's partially connected into the latching groove can come apart at any future time.

If the HES was tested and failed the service department's test, then it was bad and the QD was not fully connected by them like jcridge explained. I tend to discount an HES failure because they are so rare. Possible causes are an engine that has been overheated often or a shredded alternator belt that damaged the HES connector wire. A tech drawing a blank on the flame-out could assign blame to the HES from some past experience and replace it, only to have it not be the problem. I have seen this same (incorrect) routine assumption with people replacing their bike's regulator/rectifier when the bike doesn't charge.

An easy roadside test for GOOD fuel pump, EFI and ignition triggers of the HES is to remove the front cover and a sparkplug. Turn the key on and wrench turn the engine past TDC, listening for the fuel pump to come on and the plug to fire. I used that very test to diagnose the same "no spark, no fuelpump" symptoms at our previous NY Bash on CTRider's R1150R that would not start that morning. The complete lack of response said "bad HES" or "connective failure", but it turned out days later to be a broken or loose ground wire on the Motronic support frame. It took the dealer days to find it. Proof that a bad HES test isn't always what it seems -unless- the test is performed directly on the HES plug connector, under the fueltank!

.

[Canyon Runner]

Forgive me for losing track of the thread here... have to keep working to pay for repairs.

Rob, I am afraid that I am probably chronically of the "not enough information" camp right now, at least for those of you who have the depth of knowledge that you, and others gathered here, do. As I say, I am very much just trying to learn, and I am sure that I don't know the right things to tell you in order for you to be able to help me efficiently. I do, however, greatly appreciate your knowledge and instruction as I try to learn more.

For the record/ discussion, they did represent to me that it was internal fuel line failure. They initially put the bike through diagnostics, got red lights on the Hall sensor and replaced it, and then when they went back to run it on diagnostics, the Hall Sensor was green lights all the way around, but no fuel pressure.

This is what led them to check the fuel lines, and they found that internal lines had come off. They replaced those, and the Hall sensor.

So far, so good, but I haven't been able to really shake her out yet. (113 in the shade right now). As to what the cause of the effect was, it looks like the interpretation of the shop is garnering suspicion above all else. But, as I am sure you can guess, I have no alternate theory of my own.

[CycleRob]

More info is good. It sure looks like the blown off internal fuel line was the flame-out cause and a good HES was replaced for nothing. I say that because 2, simultaneous, unrelated failures are like a thousand to one odds.

.

[boxermania]

The notion that a HES will create excessive backpressure in the fuel system is absolute bunk. The pump max pressure is around 90 psi and this pressure is present all the way to the FPR located in front of the airbox, there the regulator feeds fuel to the injectors at 3 BAR (~44 psi) and the additional fuel is returned to the tank.

We have had several recorded instances where the fuel line inside the tank has come loose, as a result of filter replacement and the use of the wrong clamps or due to the ill fated compression bands.
Canyon Runner

I'm almost certain that the BMW Tech didn't know how to diagnose a bad HES just based on his description "the lights went from red to green". This is the basic premise that you can give a monkey a piece of diagnostic equipment without the understanding of how things work.....need I say more.

How the process evolved from here was a combination of the BMW dealer trying to save face (they were going to get paid for the HES replacement under warranty) and at the same time trying to placate you, the owner, for their innablity to diagnose the problem. They should have come clean and split the cost of the procedure with you and leave it at that.

Generally speaking there are some good BMW techs, but the list is short. Forums like this do provide not only collective assistance, but vast amounts of technical expertise. Boxers are faily easy to maintain, become intimately familiar with the maintenance and if you don't have the space, befriend someone with a boxer and do collective maintenance, a couple of beers or dinner can kep things on an even keel.

I'm glad to see that you are back on the road......