'04 No Start- Question re HES function

[tomvv11]

Bike with less than 14K started in the morning like a champ, ran great on the way to work 20 miles distant. 9 hours later, turned over fine but would not start, with neutral light on, side stand up, kill switch centered. Removed both coils and plugs, and there was spark, though they appeared kind of random and maybe irregular. Fuel pump spooled up every time ignition is turned on, and tank's full of premium.

The premium I paid BMWMOA this year for towing paid for itself next day and the bike is in my garage. Fuses are all good, per DVM. Relays are all removed and reseated. The two big ones are different colors and the schematics on their cases indicate they are not interchangeable.

When I remove each injector and crank it, they do spit fuel, though I have no experience with how much to expect or how strong a spray it should be. I think I was expecting stronger squirts, though it is only starting throttle, just off idle. If an in-tank fuel line decided to leak while I was upstairs at work, would I get no fuel or low fuel?

Battery's resting charge is 12.85V, drops to 12.5V with ignition on (headlights and computer I guess), and stays above 10V when cranking. All measured at battery terminals. I have not disconnected the battery but did turn on the ignition and crank the throttle open twice to tell the ECU what the throttle limits are. Was that a waste if I did not first disconnect and reconnect the battery?

My understanding of the HES is that ignition and fuel injection happen based on when the HES gives its signals at TDC and BDC. Not right at those moments, but somewhere in between the two pulses, guided by the Motronic. If the HES up and died, would I still get spark and fuel, just at random times relative to piston/valve timing or would they not happen at all without the Motronic being told where the pistons are?

If the O2 sensor shorted, not opened, would that confuse the Motronic or tell it to send only tiny amounts of fuel?

This is seriously F'ing with my TOR plans. If it turns out to be something major buckish like the ECU that takes care of the TOR budget too. Hoping one of you has a ray of sunshine to pass along.

That pretty well covers everything I've tried. Have not removed the tank yet, partly because it's only about a half gallon off from topped up and that kinda curbs my enthusiasm.

[JimMoore]

Whatever else, I think the tank is going to have to come off. You might as well get to work with a siphon hose and a gas can.

After that, HES issues are less common in bikes of that era. It may turn out to be the HES, but my first bet is a fueling problem. When you turn the key, do you hear the fuel pump prime? If no, you may have a bad fuel pump or a bad sidestand switch.

If the pump primes, does it sound normal? You may have a cracked fuel line or have a line blown off inside the tank. Sometimes that will make the pump sound weird.

Here are two other things to try. Once you have the tank lifted (or removed) spray some starting fluid into the intake and try to start the bike. See if the bikes starts for a few seconds.

Here's a quick check for the HES. Turn the key on and rotate the engine by hand. I'm told that the fuel pump will prime at tdc and bdc.

As a note, I'm pretty sure it's not the O2 sensor, but you can disconnect it under the tank on the right side and see if that helps.

[Groceryrun]

Here is some info on the Hall Effect Sensor ( HES ).
The older versions had insulation that disintegrated over time/temp.
The old OEM version has a hard shiny jacket.
The newer OEM version has a soft loose jacket.
Photo credits go to GSADDICT - a valued member on many BMW forums.

[tomvv11]

Thanks, gents. Probably fuel related, and I'm procrastinating the inevitable. Didn't necessarily think it would be HES on an '04, but then I wouldn't figure it to have needed starter innards repairs and stick coils at this tender mileage, each of which were previous non-start culprits.
Fuel pump cycles when ignition turned to ON. If kill switch or sidestand are in lockout position when switch is on, the pump does not cycle until I correct that switch position, which tells me the interlocks are all good.
The last time a non-start happened I checked the fuel pump assembly. I briefly turned on the ignition when the pump was dry and it seems like it's been whinier since then(maybe it's just me). Also could have put it back turned such that some part of the assembly is touching the tank that was not before. I carefully uncrimped and recrimped the factory "geez, was it really necessary to use those?" clamps, so there are lots of opportunities to screw up in reassembly.

[phlam]

I'm new to the Oilhead & ECU arena, but I do have a few years of Airhead points and condenser repair and maintenance experience trickling through my brain cells. Did it rain on the bike in those 9 hours while you were at work? Have you checked the connections between the HES and the ECU, the ECU and the coils? Do the Coils have any cracks? Is the battery fully charged?
I trust you've gathered from my questions, that corrosion is a problem where I'm located (Florida). It's been the cause of a few electrical gremlins. Good luck finding yours.

[tomvv11]

Took off the tank to check for obvious disconnections. Found none. Did test HES by turning over engine with back wheel in 6th gear, and the fuel pump cycles a couple times per wheel revolution, so HES is giving signal, I assume top and bottom. Disconnected O2 sensor, with no change.

Reset throttle limits when I reconnected battery. Starter turns over at a good clip but it just will not fire even a sputter. Rechecked injectors and they're still injecting. Beru coilover mains only have a few thousand miles on them, same with plugs. I have switched around relays that have the same pinout and functions. Don't really know which is the Motronic relay as there is no key on the covers and my Haynes manual is off a bit on what fuses and relays do what.

I'm beginning to fear ECU.

Does anyone in the greater Seattle area have a GS-911 for loan or rent? The diagnostic plug info I have for checking codes by counting DVM voltage dips is current as of Motronic 2.2, written in 1996 and I don't know if my Motronic 2.4 on a 2004 bike is the same. Counting voltage dips seems akin to interpreting smoke signals.

[brentw1]

just on the odd chance I bought a bike in seattle that had water in the bottom of the tank
on top of any fuel provided,
you can dribble some known good fuel into the throttle bodies and it should fire

[brentw1]

if you have spark and fuel probably not the ecu,
have you checked the spark timing
could be a bad ground as well

[Roger 04 RT]

These bikes are known for splitting an in tank hose. Open the top QD (fuel return line). Press in the plunger check valve on the male QD (left hand half) and turn the key on. Every time the pump cycles you should get a strong surge of fuel. If you do the intank hoses are good enough for starting.

[Chris Canning]

Looking at the figures i’d be Going battery as my first port of call.

[giarcg]

I've been down this road with my RTs....

A marginal starter can pull enough voltage to starve the ECU causing just the symptoms you're describing.

The field magnets can dislodge and more often the plate that seperates the gear reduction from the armature can detached falling into and shorting the windings on the armature. The starter will still turn the engine over but will be taking more of the available voltage to do it.

The starter is relatively easy to remove, dissasemble and inspect. If the plate is detached remove it completely and leave it out, clean the g'box and apply dri-lube. Magnets can be reattached with JB weld.

[tm1100s]

A simple test on one of the starter wires with an amp clamp would verify or eliminate a starter problem. With cranking voltage at 10v I might eliminate the starter right there but an amperage reading would be the key. Having said that, the 7 year old battery in mine cranked just fine (until the final crank that killed it), cranking sounded good but just wouldn't start. New battery and no further problems.

[tomvv11]

Originally Posted by Roger 04 RT

These bikes are known for splitting an in tank hose. Open the top QD (fuel return line). Press in the plunger check valve on the male QD (left hand half) and turn the key on. Every time the pump cycles you should get a strong surge of fuel. If you do the intank hoses are good enough for starting.

It starts! Gentlefolk, thanks for all the helpful suggestions.

For the manyeth time, Roger 04 RT gets it right, or awfully close. Using that diagnosis method I got no spurts of gas from the return line when I turned it over and held open the QD. Finally drained the nearly full tank and removed the fuel pump assembly. In the wrestling out of the assembly, found the hose into the fuel filter was completely detached, just popped off the end of the filter. Maybe pushed off by pump pressure? I'd had the assembly out to check for splits last fall when chasing another no-start that turned out to be the starter, and just maaaaaybe un- and recrimped that crimp clamp ON the knob of the filter inlet rather than below it where it would have kept the hose in place.

Not a split hose, but the effect is the same or worse. Only atmospheric pressure was pushing any fuel to the injectors. Tightened the goofy BMW crimp clamp by putting an M2 screw on either side of the waist of the crimp and squeezing with pliers. On reassembly, Vroooom.

Tempted to remove an injector now to see what a properly fed spray looks like.

[Roger 04 RT]

tomvv11, glad it's working. One of the things that blows the hoses off inside the tank is turning on the key or starting the bike with either QD not fully seated. That prevents fuel from returning to the tank and lets the pressure build from 43.5 psi (governed by the fuel pressure regulator) to roughly 100 psi. The twice normal pressure can be enough to blow open one of the six hose connections inside the tank if it wasn't fully tightened.

[Jbh1]

The week before I picked up my 2004 this year the hall sensor went out (wire issue as noted above). Unfortunately the previous owner had a costly repair a few days before I picked it up. So apparently it can happen to an 04 also. I don’t know if it had the old or new style wires on it when it failed. Bike does have 63,000 miles. FYI.

[Groceryrun]

Originally Posted by Groceryrun

Here is some info on the Hall Effect Sensor ( HES ).
The older versions had insulation that disintegrated over time/temp.
The old OEM version has a hard shiny jacket.
The newer OEM version has a soft loose jacket.
Photo credits go to GSADDICT - a valued member on many BMW forums.

Some info on HES.