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Intermittent engine cutout


Chip

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A bit of diagnosis hell or maybe a tinkerer's dream.

 

Symptoms

Over the last week, the engine has suddenly cut out 4 times. The first time, I was at a light, pulled over, hit the starter several times (lots of juice so not likely the battery). The bike started again with no problems the rest of the day.

 

A couple of times since, it's cut out while cruising at constant speed (~65mph) but only for a second or two before running again.

 

Yesterday, it cut out again. As soon as I stopped, hit the starter and she fired right up.

 

Today, no problems.

 

Status and efforts so far

1996 R1100RT w/80K miles.

Battery is a relatively new Odessy (2 years old).

Fuel filter is less than a year old.

Spark plug wires from Nology less than 1 year old.

Have done a, "wire wiggle" test (started bike on center stand and wiggled wires from the ignition switch to the frame to see if I could reproduce the problem...no luck)

I think I've ruled out gas as there's no sputtering (it's a sudden cutoff) and I'm on my 2nd tank since the first occurence of the issue.

Recent tune-up (79.5K miles) included checking plugs, adjust valves, & throttle body balance).

Except for the 4 cut-outs, the bike runs absolutely perfect (smooth in all gears and rpms, lots of power, no surging, and no ABS lights blinking)

 

My thoughts and questions

It appears to be an electrical fuel delivery issue. Do fuel pumps gradually go bad and exhibit such behavior...or do they just fail? Is there a way to test one? Would a failing relay cause such symptoms?

 

Unfortunately, I have not been able to have the engine cutoff, stop the bike, turn the key off, turn it back on, and NOT hear the fuel pump do it's thing. In other words, the only time I've had that opportunity, the pump worked as normal.

 

Fuses, damaged wiring to the fuel pump...???

Other thoughts???

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Has your HES been replaced? The wires from the HES could have the insulation worn off of therefore, the HES signal could be lost which would cause the fuel pump to cut out.

 

Usually the HES problem is worse when it's wet (i.e. riding in the rain, or after the bike is washed.)

 

You could also install a fuel pressure gage on your bike to monitor the pressure when your riding. Use a 'T' connector on the bottom hose coming out of the tank on the Right side of the bike. You should have around 45 to 50 PSI steady.

 

I would start with the HES first.

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1996 R1100RT w/80K miles.
Very likely the HES, join the club.

 

The most common problem with the HES is the disintigration of insulation in the wiring harness (this usually occurs under the heat shrink where the harness is clamped to the HES plate and is invisible until the heat shrink is removed.) The easy and permanent fix is to replace the harness wiring with something with high-temp insulation (Teflon, etc.)

 

As mentioned the problem usually first evidences itself when the bike is exposed to moisture but since you've checked most everything else and considering the model/age/mileage of your bike the HES has to be a suspect. In fact on a '96 RT with 80k miles I would recommend rebuilding the HES harness even if it doesn't turn out to the cause of this particular problem.

 

You can purchase appropriate insulated wire here or you might try a PM to bmwmick as I believe that he has some pre-made harness kits available at a reasonable cost.

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Hall effect sensor. It's the trigger that tells the Motronic when in the rotation of the engine to fire the spark. It's under the alternator pulley on the front of the engine. What happens with age is that the wiring on or to the sensor deteriorates, the insulation cracks, water gets into it, and the sensor starts working intermittently.

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HES (new cost is about $280 from beemerboneyard) is a possibility, and can be a bitch to troubleshoot. Another possibility comes to my (feeble) mind: fuses

Without knowing what the total symptoms are (i.e., do you lose the RID, do the idiot lights come on, etc), I would also suggest checking/replacing the relevant fuses. If vibration causes an momentary interrupt, you could lose the ignition/fuel temporarily. BTW - They can go bad and not look bad, so it is best to just replace them. This is a low cost check, which is a good thing.

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Hi Chip,

 

I have had the same problem with my 96 as well. It started this summer with one cut-out and again this fall. The concensus from the board was the HES. It must be done as it can leave you stranded. After looking at different articles about the fix, I'm debating if I want to tackle this one even though I'll be doing other maintenance this winter. Not sure what a shop would want for the fix but it likely will not be inexpensive.

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(i.e., do you lose the RID, do the idiot lights come on, etc),

 

RID seems fine. I don't believe I lose anything except the sound of a running motor grin.gif

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HES (new cost is about $280 from beemerboneyard)

 

I've taken a quick glance at Dana Hager's article, "Diagnosing and Replacing the Oilhead Hall Effect Ignition Impulse Sending Unit." If there was a colon (e.g., HES: Diagnosing and.... ) in that title, I guess Dana must be a Ph.D. in academia. grin.gif

 

http://users.rcn.com/dehager/service/oilhead_hall_sensors.pdf

 

Anyway, Dana says in the article that one can get a new sensor for $12.31 at Newark electronics (Part number: 96F 1986 Honeywell 2AV54 Hall-Effect Sensor). The web site is: www.newarkinone.com.

 

Replacing the harness is a time consuming task. If this is the problem, I'll probably replace the sensor too.

 

That said, I'm certainly willing to hear any more opinions about what the cause may be....

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Mike and Seth:

Thanks guys for the insight.

 

I'm going to do some HES reading (Hager's article) this evening. It sure *sounds* like this could be the problem.

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I'm going to do some HES reading (Hager's article) this evening. It sure *sounds* like this could be the problem.
One more note, be wary of positive test results if dealing with an intermittant HES. Once out of the bike I couldn't make mine fail no matter what I did, even with the HES assembly totally submerged in water(!) But upon disassembly the problem (heat damage to the insulation) was quite apparent.
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ShovelStrokeEd

One last little place to look before you go springing for the HES. Check that your left boot is not inadvertantly moving the side stand down just a bit. If it does, it could trigger the side stand switch which will cut the engine out.

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Thanks Ed.

 

I just set the bike on the center stand and wiggled the heck out of the side stand to try to get the bike to cut out. No luck. Rats! frown.gif

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...I'm debating if I want to tackle this one even though I'll be doing other maintenance...

 

Alan,

I plan on replacing the alternating belt at the same time. It'll be a bit early but why not?

 

Heck, I may even brush off some dust while I'm at it...

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Another posibility is the wiring near the "steer stem". I've read about several oilheads cutting out due to a break in the wiring going to the ignition. I think it's stressed when turning the bars to the right.

 

I would trouble shoot the HES as well, but a jiggle of the wires in that area might reveal the problem.

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...but a jiggle of the wires in that area might...

 

Thanks for the suggestion. Had that problem in the past. The, "wire wiggle" test was one my first tests. Always looking for the easy fix. grin.gif

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Chip,

Before going after the Hall Sensor, slide the fuel tank back and measure the coil. The primary should read 0.5 Ohms and the secondary will either be 13K Ohms or 7.5K Ohms (I have an early '96 R1100RT (Blue too) and my coil is one of the early 13K Ohm secondary ones. They changed in late '95 to the 7.5K Ohm coil and depending on your build-date, it could have either.

When you pull the coil, give it the 'sniff test' too. If it is shorting internally, it will smell like a burnt electronic part.

 

Mick

Tucson

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Thanks Mike. I checked it out.

 

Also noticed they have a coil as well...at a reasonable price.

 

I plan on doing the "sniff" test recommended by Mick. Heck, I may even borrow one of those electrical test thingies and check the ohms. If the coil is bad, will get one from Euro...

 

This weekend is a bust (have to leave town) for tinkering on the scooter so will not be able to tear the tupperware off and deal with the engine cut out. That said, when I do, I'll post the results. If all works out well, I just may keep the bike thumbsup.gif

 

Many thanks to all on this great board.

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