HES harness replacement saga (cold starting issues)

[Parrothead]

Hi all,

 

96RT w/ 65K on the clock. BMWmick wiring harness replaced about 2 weeks ago. Bike worked without issue for the first week, since then it has stranded me 3 times when cold . Never experienced this problem before, always when hot the bike would shut down for no reason and restart when it cooled. Recently on cold starts, pump cycles, turns over, smell gas, but she won't lite-up............now what? I haven't confirmed a no spark theory, I'll check that tonight. If no spark, what could be the problem, what is happening?

 

All help is, and as always, much appreciated.

 

alan

[T__]

Hi all,

 

96RT w/ 65K on the clock. BMWmick wiring harness replaced about 2 weeks ago. Bike worked without issue for the first week, since then it has stranded me 3 times when cold . Never experienced this problem before, always when hot the bike would shut down for no reason and restart when it cooled. Recently on cold starts, pump cycles, turns over, smell gas, but she won't lite-up............now what? I haven't confirmed a no spark theory, I'll check that tonight. If no spark, what could be the problem, what is happening?

 

All help is, and as always, much appreciated.

 

alan

 

Alan, you really need to do that test for spark..

Assuming NO spark I would put the Hall Sensor at the top of my list as it didn’t have the problem before you messed with it..

 

I guess to do it right- first you should make sure the coil is getting power,, then if it is figure out if the computer is controlling the coil, then if it isn’t suspect the Hall Sensor or it’s wiring/connectors as a likely place of the malfunction.. Maybe as simple as one of the terminals is partially pushed out of the connector & not making good contact when cold..

 

Twisty

[Parrothead]

Twisty1,

 

Thanks for the info. But why would the sensor be a problem now? Fate, luck, coincidence, did I damage it somehow??? &%$@, I am really pissed! I do like the idea of a terminal not making contact, that makes more sense. Follow me here, the bike would not start one morning after a night in the garage. I rolled it out onto the street but it would not start. It baked in the sun all day and when I got home, she fired right up. Today again it would not start in the garage. After the spark test tonight, I'll put it on the street tomorrow morning, let the suns rays warm the wiring and try restart in the evening. If the bike fires up again, twisty1 may be on to something .

 

I have to be honest, the thought of spending more time in a blazing garage makes me sick. If the bike lites-up, maybe I'll just take it to the shop and let them play.......I'm really not in the mood for this. I'll post the spark results, but just my luck the bike will start tonight and ruin the connection theory.

[smiller]

Your problem likely has something to do with the work you did but it may not be with the replacement HES itself. Could be a loose connector or terminal as was suggested, or perhaps something else that you disturbed (the wiring to the ignition switch has been known to give similar trouble, for instance.) Unfortunately you may be down to extending the fuel lines and connections to the tank (so you can run the bike with the tank off and have access to everything) and wiggling stuff until you can toggle a change for the better or worse. Actually not that difficult but no fun in a hot garage, that one I know...

[Parrothead]

Thanks smiller,

 

Just what I wanted to hear, an electrical gremlin hiding out in my bike, in a hot garage in Vegas. Not for me this time around, no time and the push to tear it down again and fish does not make me happy. The sun test may shed some light (no pun intended). If it starts under those circumstances, the connection theory has some merit, but it goes to the shop. I relay to them my saga and give them the keys. Never had problems like this with my Hondas........

[bmwmick]

Hi all,

 

96RT w/ 65K on the clock. BMWmick wiring harness replaced about 2 weeks ago. Bike worked without issue for the first week, since then it has stranded me 3 times when cold . Never experienced this problem before, always when hot the bike would shut down for no reason and restart when it cooled. Recently on cold starts, pump cycles, turns over, smell gas, but she won't lite-up............now what? I haven't confirmed a no spark theory, I'll check that tonight. If no spark, what could be the problem, what is happening?

 

All help is, and as always, much appreciated.

 

alan

 

Alan,

If you find that the wiring job you did IS the problem. Let me know. No spark 'could' mean you got the TDC sensor a little too hot when you soldered in the High temp harness. I've never had that happen but it's possible.

 

Mick

[Parrothead]

Hi bmwmick,

 

Thought you would chime in sooner or later. The no spark theory is out the window, I have spark and fuel, but no start. A shocking experience to say the least. What next? Strange that it took a week to show up. I'm going to park the bike in the sun tomorrow and see if it starts in the evening. If so, may have a crimped or lose wire somewhere that when warms, gives me the connection I need. Thanks everyone for the help and ideas. We'll get to the bottom of this sooner or later..........

[T__]

Alan, were your spark plugs full of fuel when you pulled them out? Maybe you have too much fuel!

 

Basically if you have spark (you seem to) & have fuel (again you think you do) & have spark (at the correct time) & have compression (hard to believe that would come & go) it will start..

So something in the above isn’t as you think..

 

*Are you sure you have fuel (have you actually pulled an injector & watched it spray while cranking?

If the plugs are wetted with fuel maybe it is overfuling & the plugs are drying off after it sits in the sun a while.. If it is overfuling suspect an incorrectly attached fuel return hose at the fuel tank or a kink or pinch in the fuel return hose (will drive fuel pressure very high)..

 

*What kind of a spark do you have? It needs to be bluish in color & snappy.. If yellow or wimpy it won’t be enough to do the job under cylinder compression.. As a test- take an old (known good) spark plug & open the electrode gap to 3/16” (use a 3/16” drill bit as a gap gauge).. Install the special plug in the plug wire on one side & lay it on the cyl block or cyl head (make sure the other side cylinder spark plug is connected also as it is needed as ground path).. Then crank the engine & look for a bluish colored spark to jump that 3/16” gap.. If so, then you have enough spark to do the job..

 

* I presume you have compression but it wouldn’t hurt to check it cranking cold..

 

-If all good per above then pop the timing hole cover out & put a timing light on one of the spark plug wires & crank the engine.. If the timing is close I should flash the T-light with the DC to S marks somewhere visible in the timing hole..

 

 

Twisty

[Tipover_Bob]

Hi all,

 

96RT w/ 65K on the clock. BMWmick wiring harness replaced about 2 weeks ago. Bike worked without issue for the first week, since then it has stranded me 3 times when cold . Never experienced this problem before, always when hot the bike would shut down for no reason and restart when it cooled. Recently on cold starts, pump cycles, turns over, smell gas, but she won't lite-up............now what? I haven't confirmed a no spark theory, I'll check that tonight. If no spark, what could be the problem, what is happening?

 

Alan:

I hate intermittent problems too. If it won't start cold, I would be surprised if too much fuel is a problem. I would lean to possibly a coil problem. I get the impression that the R bikes have only one coil. If so, why not change out the coil temporarily if that is possible?

 

Tipover Bob

[bmwmick]

Alan,

I agree, you should pull an injector and watch for a spray while cranking cold.

The lower sensor 'can' cause the injectors not to pulse if it's not working cold.

I have seen ONE Motronic failure that was failing cold. It was a burnt resistor that would work warm but fail cold. I doubt that is YOUR problem.

 

Mick

[outpost22]

Hi all,

 

96RT w/ 65K on the clock. BMWmick wiring harness replaced about 2 weeks ago. Bike worked without issue for the first week, since then it has stranded me 3 times when cold . Never experienced this problem before, always when hot the bike would shut down for no reason and restart when it cooled. Recently on cold starts, pump cycles, turns over, smell gas, but she won't lite-up............now what? I haven't confirmed a no spark theory, I'll check that tonight. If no spark, what could be the problem, what is happening?

 

Alan:

I hate intermittent problems too. If it won't start cold, I would be surprised if too much fuel is a problem. I would lean to possibly a coil problem. I get the impression that the R bikes have only one coil. If so, why not change out the coil temporarily if that is possible?

 

Tipover Bob

 

I think those coils are about $300.00 You might want to check the coil with a tester. It's a cheaper way to be sure

[T__]

Hi all,

 

96RT w/ 65K on the clock. BMWmick wiring harness replaced about 2 weeks ago. Bike worked without issue for the first week, since then it has stranded me 3 times when cold . Never experienced this problem before, always when hot the bike would shut down for no reason and restart when it cooled. Recently on cold starts, pump cycles, turns over, smell gas, but she won't lite-up............now what? I haven't confirmed a no spark theory, I'll check that tonight. If no spark, what could be the problem, what is happening?

 

Alan:

I hate intermittent problems too. If it won't start cold, I would be surprised if too much fuel is a problem. I would lean to possibly a coil problem. I get the impression that the R bikes have only one coil. If so, why not change out the coil temporarily if that is possible?

 

Tipover Bob

 

I think those coils are about $300.00 You might want to check the coil with a tester. It's a cheaper way to be sure

 

Eaiser yet, why not just check for a spark when cold? If it will jump a 3/16" gap it has plenty of spark to start it..

 

Twisty

[Fugu]

HOW MUCH fuel spray do you have?

 

A friend's RT recently died and it turned out to be a problem w/ the fuel line. While he's diagnosing it on the side of the road, me on the phone, he's telling me there is fuel spraying out of the pulled injector.

 

It wasn't ENOUGH fuel - so if you have a spray, but haven't seen the spray from a properly operating injector, you might have not enough fuel while you are still seeing some spray.

 

If anybody's got a picture of the spray from a properly operating injector that might be a great big help.

[Parrothead]

Hi all,

 

Spark last night was blue and snappy and I could smell fuel being blown out the plug hole. The plug was dry. How much or how little fuel has not been established. Crimped fuel line, a funky connection, bad sensor, many things are possible. I want the bike to sit in the sun today, see what happens.

[Parrothead]

I'm now thinking fuel