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R1100RT runs for a moment then quits


rlusher

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Hello all. I recently completed some head work on my 99 R100RT. While everything was apart, I had the injectors serviced, replaced the spark plugs, adjusted valves, and replaced the air filter.

 

When I start the engine, it runs, but only for a few seconds (maybe 30 or so), then dies. It will run a little longer if I give it gas, bit will eventually die. It also backfires while running. I confirmed solid/equal compression in both cylinders and ensured the valves are operating properly, so am [fairly] confident all that is in good order.

 

I am wondering if there is something related to timing I missed.

 

Any suggestions are greatly appreciated. Thanks!

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Seems like it may be related.to the injectors. If timing is on, and the air filter is ok, I would go back to the fuel. Any else happen while you service and replaced? Usually when an error occurs after.servicing, it is because of something that was done in the sub system.

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roger 04 rt
Hello all. I recently completed some head work on my 99 R100RT. While everything was apart, I had the injectors serviced, replaced the spark plugs, adjusted valves, and replaced the air filter.

 

When I start the engine, it runs, but only for a few seconds (maybe 30 or so), then dies. It will run a little longer if I give it gas, bit will eventually die. It also backfires while running. I confirmed solid/equal compression in both cylinders and ensured the valves are operating properly, so am [fairly] confident all that is in good order.

 

I am wondering if there is something related to timing I missed.

 

Any suggestions are greatly appreciated. Thanks!

 

Give us a little more info, during the 30 seconds does it run smoothly?

 

Check that the RH throttle cable ferrule (and all of them) is seated properly. Check that QDs are fully seated.

 

It may also be your in tank hoses. Check that there is fuel flowing in the return line at idle.

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As above, check fuel supply because this sounds like fuel starvation. If hoses and connections are verified OK then check fuel pressure, or at least power to the fuel pump. When you initially turn on the key the ECU momentarily energizes the fuel pump relay to bring up fuel line pressure (the noise you hear when you first turn the key), then after the bike starts signals from one of the HES pickups tell the ECU to continue to power the fuel pump. If the signal from the particular HES pickup is lost the fuel pressure will quickly bleed off after starting, which would cause rough running/backfiring as the fuel supply runs out. Would be a bit of an odd failure, but something easy to check.

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If both throttle cables are seated properly, the pump primes then stops when the ignition is switched on and the valve timing has been correctly set, I too would consider a malfunction of the HES as a possibility. Is the HES connector to the main loom clean and tight? (Same applies to the connector by the tank). When my HES went bad the engine would run for a while then stop and it wouldn't restart until the engine had cooled down. This turned out to be a faulty sensor. However, the fault on mine was heat-related and until it stopped the engine ran fine. I feel that, if it is the HES in yours, it is morelikely to be a wiring or connection issue. I offer this only as a possibility; it could well be something else.

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Morning Rick

 

The fuel starvation possibilities are well covered above.

 

Can you remember what the RID oil temp gauge was doing when it acted up? If working normally then look into the fuel things mentioned above, or even a problem with with the HES.

 

If the oil temp gauge was acting strange then look into the oil temperature sensor on the engine (to right & behind alternator) not working correctly or the harness not fully plugged into the sensor.

 

Way down the list-- but also check that BOTH side spark plug wires are FULLY plugged into the coil (they can sometimes pull part way out of the coil while working on the bike)

 

Have you re-verified that the headwork-side cam timing is spot on?

 

You might also try running it with the CCP removed as a test, or try running it with the o2 sensor disconnected.

 

More info on exactly what was done to the engine & cyl head would also help us.

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Hello, Rick -

Do you think you might have put it together with the fuel lines reversed?

Here's a link.

 

+1 on this if you removed the gas tank.

 

Couldn't be an HES problem because HES is a go, no go problem. In other words, it wouldn't cause the repeatable symptoms you described. Engine would either run, or not with no spark at the plugs

 

Definitely sounds fuel related.

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Thank you all for the quick responses!! Let me provide some more information:

 

1. I removed the head to have the boss that contains the valve cover bolt threads repaired (when I removed the valve cover for an adjustment, I discovered one of them was cracked). While this head was off, I removed the other one to clean it up and replaced both head gaskets. I also did the other items listed in my original post.

 

PLEASE LET ME KNOW IF THERE IS SOMETHING ELSE TO CHECK WITH REGARD TO TIMING. I made sure each side was at TDC when re-assembling, made sure the rocker arms/pushrods were in a neutral position, and that the camshaft lined up with the timing chain sprocket (there are notches on both, and arrows on the sprocket).

 

2. I removed the HES and tested it cold and under some heat and it worked fine.

 

3. I did not actually remove the fuel tank, other than moving it out of the way to get to the HES, so the full lines should not be an issue. Per DR's suggestion, I will check the plug wires at the coil, since I did move the tank around quite a bit during all this. I also made sure the hoses were not kinked or anything.

 

4. No issues with any gauges acting weird or anything.

 

5. It does run pretty smoothly at first, then rough before shutting off. I did try removing the CCP and that did not really change anything.

 

Thanks again!!

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Afternoon Rick

 

OK that helps some--

 

Does your bike still have the Evap canister on the rear & is it hooked up?

 

If so then try plugging the vacuum line going to the bottom of the Throttle Bodies (just pull the vac line off of both TB's then plug the nipples on the TB's

 

If the tank was tilted you might have flooded the Evap Can with raw gasoline. If that happened your system might go super rich when the Evap solenoid opens after it runs a short while.

 

You didn't by chance get your o2 sensor wire pig tail zip tied up next to the R/H spark plug wire did you? (if so move it)

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Thanks DR!

 

Mine does, in fact, have the canister, and it is connected. I will try plugging the TB vacuum nipples and see what that does. I did move the tank around a lot so it is certainly possible this happened. How long would it have to run for this to clear up?

 

I am not sure where the O2 sensor plug ended up, but I did move it around, so will double-check that as well. Why is this important?

 

Thanks again!!

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I am not sure where the O2 sensor plug ended up, but I did move it around, so will double-check that as well. Why is this important?

 

Afternoon rlusher

 

Because (IF) the high frequency from the plug wire radiates into the o2 sensor pig tail (cross talk) that high frequency can end up entering the Motronic (fueling computer) & scrambling it's fueling & spark control.

 

Usually shows up a an erratic idle quality, or a stalling issue, but who knows what it can ultimately effect. (just something else to check & eliminate from the list of possibilities)

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  • 2 weeks later...

Hello all. As a follow up to my post about my R1100RT running for a bit, then quitting. I have a couple of more questions:

 

1. Do the spark plugs fire at the same time? I read on another forum that one cylinder fires at a slightly different time. This makes me wonder if, when I was reassembling valves/rocker arms/heads, I messed up the order so that now the spark plugs are not firing at the right time. To recap, it runs fine for a few seconds, then quits, but will keep running roughly if I give it throttle.

 

2. My motorcycle riding friend (also amateur mechanic) listened to it and says he believes that something is wrong with the timing, and that it would be worth replacing the HES (I had a car mechanic friend say the same thing) even though I checked it with a LED light (recommended in Dana Hager's document) and it appears to be fine.

 

Thoughts/wisdom?

 

As always, thanks!!

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Afternoons Rick

 

Yes, both spark plugs SPARK at the same time but both cylinders do not FIRE at the same time. (it sparks on every piston-up revolution but only fires every other revolution).

 

It could still be a bad HES (actually bad HES wiring) even though your test box (LED light) shows the HES working OK. The test LED is more for ignition timing check than HES function.

 

The test LED will show the Hall Switch working but can't always show crosstalk in failed HES wiring.

 

 

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Thanks DR, especially for clarifying "spark" and "fire". I used the terms interchangeably, but now see that there is a difference. What you are saying makes sense.

 

In all this, I messed up the timing more than once. Can this damage the sensor, or do they only really break due to wiring?

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Afternoon Rick

 

Unless you left the HES loose & the timing cup hit it then you can move it all you want & not damage the sensor. But you still need the get the ign timing fairly close to make it run right & protect the engine from too much or too little spark advance.

 

On the wiring thing? Almost always it's the wiring breaking down that causes the problem & very/very seldom the sensor itself.

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Hi DR. Please explain "protecting the engine". If there is too much or too little spark advance, what can happen? Thanks in advance!

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Hi DR. Please explain "protecting the engine". If there is too much or too little spark advance, what can happen?

 

Morning rlusher

 

More to it that than the below but these are the basics--

 

Not enough spark advance = engine running hot, exhaust valve's seeing lots of heat, & exhaust running extremely hot.

 

Too much spark advance = knocking, possible hole burnt in piston & possible valve damage.

 

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OK. I did notice that it seemed to run hot when I was first trying to get it running after putting everything back together. Would this support that the sensor is not working right? Thanks.

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OK. I did notice that it seemed to run hot when I was first trying to get it running after putting everything back together. Would this support that the sensor is not working right? Thanks.

 

Moring rlusher

 

No, not necessarily so, at least without other indicators to point to the HES.

 

At the moment we just don't have enough background info on your problem to point you at anything in particular.

 

You know your bike's history & the problem's history but we don't so we can't even take an educated guess at your present problem.

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Thanks DR. I'll keep plugging away at it. Do you think it is worth trying a new sensor? That is kind of what I am leaning toward doing, to rule it out if nothing else.

 

I greatly appreciate the input!

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Thanks DR. I'll keep plugging away at it. Do you think it is worth trying a new sensor? That is kind of what I am leaning toward doing, to rule it out if nothing else.

 

I greatly appreciate the input!

 

Afternoon Rick

 

Sure,(IF) you have the money & time to do that.

 

Otherwise you will just have to keep troubleshooting until you find what's going wrong.

 

Personally I would watch the fuel return (from regulator forward) to verify the fuel system is maintaining fuel pressure/flow at stall.

 

Then try it with the o2 sensor disconnected.

 

If OK on the fuel pressure/flow & the o2 sensor disconnect doesn't help then move on to other things.

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just my 5 cents, probably not what you have, but i had a bad HES ( from what i remember from testing it was one of the sensors and not the wiring, unusual) and it resulted in similar symptoms, engine starting running a bit, running a bit longer if i gave more gas, but dying within 20 secs or so. it was running rough when it did.

good luck

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Couldn't be an HES problem because HES is a go, no go problem. In other words, it wouldn't cause the repeatable symptoms you described. Engine would either run, or not with no spark at the plugs.

No, there are two HES pickups: one supplies spark timing and the other injection timing (and also an 'engine running' signal so the ECU knows to continue to power the fuel pump relay.) It's possible to have one pickup fail (or an associated wiring issue) and not the other, so it's possible for an HES issue to show spark but no fuel, or vice-versa.

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Thank you schneeman and smiler for the additional info. I just, somewhat reluctantly because of the cost, ordered a new sensor, so this gives me some additional hope that the sensor might actually be the culprit.

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If you haven't done the HES, go ahead.

Even if it isn't the culprit, now, it will be on an older oilhead eventually.

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