'00 RT Surging, Wown't hold speed, but runs/starts

[blsexton]

A little help from those of you who may KNOW.

(To clarify a little more, this is not a simple 'known issue' surge, it's a full fledged SURGE/NO Juice popping feeling, like "I'm gonna have to pull over and the bike is dying one second to "oops, it's OK now....")

 

47k mile R1100RT, mechanically excellent until now.

Last year just before being put away for winter-

Filled with gas and right after started to run very rough

-Surges (especially at lower speeds. Hot or Cold)

-Starts rough (but always seems to start)

-Idles "OK" but not great

-When whacking open the throttle at speed bike is very sluggish to respond, almost feels like it's being flooded, but sometimes will 'liven up' as if it finally came into the right setting

 

Ran bike last year for 200 miles like this, then put away for winter.

 

This spring, replaced with clean fresh Gas (no old stuff left in tank), replaced plugs, changed fuel filter.

Fully charged battery, replaced all fuses

 

24 mile test ride and....

SAME THING!

Checked TPS sensor, volts respond as they should.

Bike was synched about 4k miles ago and throttle cable replaced by well trusted mechanic.

 

Now 'Guessing' HALL Sensor, but from what I read when the sensors fail it sounds much more serious than the issues I'm facing.

 

Suggestions please?

[dirtrider]

Evening blsexton

 

Not enough info to pin it down--

 

What are the dash lights & gauges doing when it surges?

 

What is the tac doing?

 

Might be an o2 sensor going wacky so remove the CCP then ride it to see if that makes a difference.

 

Could be the HES but that doesn't fit the normal HES failure mode.

 

Could be a fuel pump or pump relay acting up, or possibly an in-tank pressure hose issue. (see if you have return fuel flowing back to the fuel tank, no return fuel flow indicates a low pump pressure)

 

If your bike has a Techlusion or fuel nanny then that is the place I would start looking (if you have one then completely disconnect it then ride the bike)

 

This is a difficult thing to diagnose but I have seen an 1100 sort of act like you are seeing & it turned out to be a bad Motronic (the only way we found it was to substitute a known good Motronic from another good running bike)

 

If you can catch the tac going crazy, or RID or dash lights doing something unusual then that might give us a diagnostic direction to look in.

 

Otherwise you will probably have to start testing fuel flow/pressure, rig up a test light on the & injectors circuit, & possibly coil circuit. Maybe rig up a test light on the fuel pump circuit.

 

Anything done to the bike (accessory wise or maintenance wise) just prior to the problem showing up?

 

As you have found it is difficult to find a problem like you have when riding & working on the bike & even more difficult over the internet. So the more DETAILED info you can furnish the better we can help you.

 

 

 

 

 

 

 

 

[blsexton]

DirtRider thanks! Replies in all caps so it's easier to read:

Evening blsexton

 

Not enough info to pin it down--

 

What are the dash lights & gauges doing when it surges?

NO EFFECT

 

What is the tac doing?

NOTHING DIFFERENT (SLIGHT MODS BUT DUE TO ENGINE, NO BOUNCING OR ERRATIC BEHAVIOR)

 

Might be an o2 sensor going wacky so remove the CCP then ride it to see if that makes a difference.

HAS A REMUS EXHAUST FITTED. "EURO MAPPING HAS BEEN ACTIVATED" (WORDS OF PREVIOUS OWNER) BY REMOVIG/CHANGING THE FUEL RELAY THINGY....(POSSIBLE ISSUE HERE...NOT A CLUE WHAT HE'S TALKING ABOUT)

 

Could be the HES but that doesn't fit the normal HES failure mode.

 

Could be a fuel pump or pump relay acting up, or possibly an in-tank pressure hose issue. (see if you have return fuel flowing back to the fuel tank, no return fuel flow indicates a low pump pressure)

 

If your bike has a Techlusion or fuel nanny then that is the place I would start looking (if you have one then completely disconnect it then ride the bike)

 

 

This is a difficult thing to diagnose but I have seen an 1100 sort of act like you are seeing & it turned out to be a bad Motronic (the only way we found it was to substitute a known good Motronic from another good running bike)

 

If you can catch the tac going crazy, or RID or dash lights doing something unusual then that might give us a diagnostic direction to look in.

 

Otherwise you will probably have to start testing fuel flow/pressure, rig up a test light on the & injectors circuit, & possibly coil circuit. Maybe rig up a test light on the fuel pump circuit.

 

Anything done to the bike (accessory wise or maintenance wise) just prior to the problem showing up?

NO

 

As you have found it is difficult to find a problem like you have when riding & working on the bike & even more difficult over the internet. So the more DETAILED info you can furnish the better we can help you.

 

 

 

 

 

 

 

[dirtrider]

 

Might be an o2 sensor going wacky so remove the CCP then ride it to see if that makes a difference.

HAS A REMUS EXHAUST FITTED. "EURO MAPPING HAS BEEN ACTIVATED" (WORDS OF PREVIOUS OWNER) BY REMOVIG/CHANGING THE FUEL RELAY THINGY....(POSSIBLE ISSUE HERE...NOT A CLUE WHAT HE'S TALKING ABOUT)

 

 

Evening blsexton

 

Look inside your fuse box at the spot called (coding plug Motronic) in the attached picture & tell us what is there (what color) or if there is nothing there.

 

I won't be back on this site until tomorrow morning__

[Jim Moore]

Also make sure all those fuses and relays are pressed completely into their slots.

[eddd]

 

Some of the diagnostic steps might seem a bit daunting, but check out the easy to do ones first so those are off your list.

 

Checking the fuel pressure isn't too difficult or expensive. You can purchase an inexpensive fuel pressure gauge from Harbor Freight or often you can borrow/rent one from the local parts store. You'll need a fuel injection gauge. Keep in mind that a properly operation pump will produce over 40 psi. That is enough pressure to overcome regular worm-type fuel clamps, use caution.

 

I have a functioning Motronics that I could send you to use in your diagnosis, no cost.

 

 

[roger 04 rt]

Some of the diagnostic steps might seem a bit daunting, but check out the easy to do ones first so those are off your list.

 

Checking the fuel pressure isn't too difficult or expensive. You can purchase an inexpensive fuel pressure gauge from Harbor Freight or often you can borrow/rent one from the local parts store. You'll need a fuel injection gauge. Keep in mind that a properly operation pump will produce over 40 psi. That is enough pressure to overcome regular worm-type fuel clamps, use caution.

 

I have a functioning Motronics that I could send you to use in your diagnosis, no cost.

 

 

Eddd, I've used a fuel pressure gauge and the return volume test and think the return volume test is better and easier.

 

Since the fuel pressure regulator rarely fails but hoses and clamps regularly do, all you need to check is that fuel is returning to the tank. If it is you have 43.5 psi and there is enough fuel to start the motor.

 

Once running, if you measure the volume of fuel in one minute to be about 2 liters then you know you have pressure and full pump/filter/hose performance.

 

If you only measure fuel pressure, there can be a lot of in-tank leaking and you will still get 43.5 psi, since the pump has about 3X the capacity needed at even WOT.

[Jmacaz]

Plugged up catalytic converter?

 

[flars]

If you had the bodywork off before the problem started, make sure the throttle cables are both sitting cleanly in their holder/adjuster down by the throttle bodies.

[dirtrider]

Plugged up catalytic converter?

 

Morning Jmacaz

 

 

Even if it is plugged it shouldn't be effecting his performance as the cat is probably sitting on a shelf somewhere.

 

He says his bike has a Remus exhaust system on it.

[eddd]

Some of the diagnostic steps might seem a bit daunting, but check out the easy to do ones first so those are off your list.

 

Checking the fuel pressure isn't too difficult or expensive. You can purchase an inexpensive fuel pressure gauge from Harbor Freight or often you can borrow/rent one from the local parts store. You'll need a fuel injection gauge. Keep in mind that a properly operation pump will produce over 40 psi. That is enough pressure to overcome regular worm-type fuel clamps, use caution.

 

I have a functioning Motronics that I could send you to use in your diagnosis, no cost.

 

 

Eddd, I've used a fuel pressure gauge and the return volume test and think the return volume test is better and easier.

 

Since the fuel pressure regulator rarely fails but hoses and clamps regularly do, all you need to check is that fuel is returning to the tank. If it is you have 43.5 psi and there is enough fuel to start the motor.

 

Once running, if you measure the volume of fuel in one minute to be about 2 liters then you know you have pressure and full pump/filter/hose performance.

 

If you only measure fuel pressure, there can be a lot of in-tank leaking and you will still get 43.5 psi, since the pump has about 3X the capacity needed at even WOT.

 

The return volume test is a good indicator and is a good place to start since it doesn't require a pressure gauge, but it is not fool proof. Measuring the actual fuel pressure will tell you exactly what your pump is putting out. I rode an RT over 1000 miles back to the house on a dying fuel pump. It was delivering more than enough volume, but the pressure was inadequate to allow the injectors to operate as designed.

[dirtrider]

Afternoon Eddd

 

Actually you need Enough Volume at Enough Pressure.

 

Pressure test alone won't show volume & volume test alone won't show pressure.

 

The post-regulator flow test that Roger is referring to tests BOTH (volume at regulator-regulated-pressure) so it is showing Real World Flow at Working Pressure (in my book no better test than this one)

[AndyS]

Once running, if you measure the volume of fuel in one minute to be about 2 liters then you know you have pressure and full pump/filter/hose performance.

 

What is your technique for performing this test?

[eddd]

Afternoon Eddd

 

...Actually you need Enough Volume at Enough Pressure.

 

Pressure test alone won't show volume & volume test alone won't show pressure...

 

Obviously, and I never said otherwise.

 

...but since a correctly functioning pressure regulator only opens to return fuel to the tank when the fuel pressure exceeds 43.5 psi a lack or diminished amount of fuel in the return line does not tell you the definitive condition of your pump. It is telling you that the pump's pressure is below 43.5 psi or the regulator is not functioning properly (not opening at pressure above 43.5 psi). While not common, pressure regulators have been know to fail.

 

If you stop your diagnosis with the return fuel test you are dismissing the possibility that the pressure regulator could be defective. In the case of the OP, blsexton, if there is no or diminished fuel in the return fuel test one might assume a faulty pump and waste money by throwing parts at the problem.

 

Even if the regulator were functioning correctly, a lack of or diminished return fuel volume doesn't mean the cause of the problem has been found. A fuel pressure of say, 40 psi would not open the fuel pressure regulator, but might be high enough that it has nothing to do with the OP's problem. If the pressure were at the 40 psi used for this illustration the pump should be replaced, but there is no guarantee that the problem has been addressed.

 

Using a fuel pressure gauge is a simple procedure that will provide you with precise information and is a sound diagnostic procedure. One that you referenced in your initial response to blsexton.

 

 

Evening blsexton

 

Not enough info to pin it down...

 

Otherwise you will probably have to start testing fuel flow/pressure, rig up a test light on the & injectors circuit, & possibly coil circuit. Maybe rig up a test light on the fuel pump circuit...

 

 

 

blsexton, I hope you find some information here that is useful as you try to sort out the cause(s) of the problem.

 

[dirtrider]

 

 

blsexton, I hope you find some information here that is useful as you try to sort out the cause(s) of the problem.

 

Afternoon Eddd

 

He won't if we keep fighting with each other & giving him conflicting information on how to do a simple fuel test so I will back out of this thread & let you work with him.

 

Afternoon Blsexton, Eddd will take over & work with you, if you require any specific info I can offer just feel free to PM me.

[roger 04 rt]

Afternoon Eddd

 

...Actually you need Enough Volume at Enough Pressure.

 

Pressure test alone won't show volume & volume test alone won't show pressure...

 

Obviously, and I never said otherwise.

 

...but since a correctly functioning pressure regulator only opens to return fuel to the tank when the fuel pressure exceeds 43.5 psi a lack or diminished amount of fuel in the return line does not tell you the definitive condition of your pump. It is telling you that the pump's pressure is below 43.5 psi or the regulator is not functioning properly (not opening at pressure above 43.5 psi). While not common, pressure regulators have been know to fail.

 

If you stop your diagnosis with the return fuel test you are dismissing the possibility that the pressure regulator could be defective. In the case of the OP, blsexton, if there is no or diminished fuel in the return fuel test one might assume a faulty pump and waste money by throwing parts at the problem.

 

Even if the regulator were functioning correctly, a lack of or diminished return fuel volume doesn't mean the cause of the problem has been found. A fuel pressure of say, 40 psi would not open the fuel pressure regulator, but might be high enough that it has nothing to do with the OP's problem. If the pressure were at the 40 psi used for this illustration the pump should be replaced, but there is no guarantee that the problem has been addressed.

 

Using a fuel pressure gauge is a simple procedure that will provide you with precise information and is a sound diagnostic procedure. One that you referenced in your initial response to blsexton.

 

 

Evening blsexton

 

Not enough info to pin it down...

 

Otherwise you will probably have to start testing fuel flow/pressure, rig up a test light on the & injectors circuit, & possibly coil circuit. Maybe rig up a test light on the fuel pump circuit...

 

 

 

blsexton, I hope you find some information here that is useful as you try to sort out the cause(s) of the problem.

 

If the regulator is functioning correctly (highly likely) and the pressure was 40 psi, there would be no flow in the return line.

 

If the volume in the return line is low, at idle, there is a problem in the tank. Diminished return volume at IDLE is ALWAYS an indicator of a serious problem.

 

Interestingly, even if the fuel pressure regulator was 38 psi, the bike would run perfectly fine if the pump, fuel filter and hoses in the tank were working. The reason is that a 15% drop in fuel pressure only reduces injector fuel delivery by a little under 7%. The Motronic, using Closed Loop Mixture Adaptation, will correct the entire fuel map just fine.

 

And then the other situation is you could measure 43.5 psi in the supply line but not measure return volume. In that case, with leaking hoses, you could easily have insufficient volume for operation at mid-high engine loads.

 

If you want the very best test of your fuel system:

 

--check the return volume

--check the supply pressure at idle, with the alternator charging

--send your injectors out to have them cleaned and measured.

[eddd]

 

If the regulator is functioning correctly (highly likely) and the pressure was 40 psi, there would be no flow in the return line.

 

Interestingly, even if the fuel pressure regulator was 38 psi, the bike would run perfectly fine if the pump, fuel filter and hoses in the tank were working. The reason is that a 15% drop in fuel pressure only reduces injector fuel delivery by a little under 7%. The Motronic, using Closed Loop Mixture Adaptation, will correct the entire fuel map just fine.

 

The part of mine you put in red is in agreement with what you are stating.

 

 

 

[eddd]

 

 

blsexton, I hope you find some information here that is useful as you try to sort out the cause(s) of the problem.

 

Afternoon Eddd

 

He won't if we keep fighting with each other & giving him conflicting information on how to do a simple fuel test so I will back out of this thread & let you work with him.

 

Afternoon Blsexton, Eddd will take over & work with you, if you require any specific info I can offer just feel free to PM me.

 

I don't see where additional correct information is conflicting.

[roger 04 rt]

 

If the regulator is functioning correctly (highly likely) and the pressure was 40 psi, there would be no flow in the return line.

 

Interestingly, even if the fuel pressure regulator was 38 psi, the bike would run perfectly fine if the pump, fuel filter and hoses in the tank were working. The reason is that a 15% drop in fuel pressure only reduces injector fuel delivery by a little under 7%. The Motronic, using Closed Loop Mixture Adaptation, will correct the entire fuel map just fine.

 

The part of mine you put in red is in agreement with what you are stating.

 

There were two competing lines of reasoning.

--One line of debugging said rule in/out a fuel issue by checking return volume.

--The other said check fuel pressure to achieve that end.

 

The difference of approach led to some arm wrestling among us.

 

Either or both tell you something. But the return volume test is faster, takes no gauges or special equipment and is more comprehensive.

[eddd]

 

If the regulator is functioning correctly (highly likely) and the pressure was 40 psi, there would be no flow in the return line.

 

Interestingly, even if the fuel pressure regulator was 38 psi, the bike would run perfectly fine if the pump, fuel filter and hoses in the tank were working. The reason is that a 15% drop in fuel pressure only reduces injector fuel delivery by a little under 7%. The Motronic, using Closed Loop Mixture Adaptation, will correct the entire fuel map just fine.

 

The part of mine you put in red is in agreement with what you are stating.

 

There were two competing lines of reasoning.

--One line of debugging said rule in/out a fuel issue by checking return volume.

--The other said check fuel pressure to achieve that end.

 

The difference of approach led to some arm wrestling among us.

 

Either or both tell you something. But the return volume test is faster, takes no gauges or special equipment and is more comprehensive.

 

I'm clear on what you are saying, but the point I was making is that the fuel volume return test does not take into account a faulty pressure regulator, but more importantly it could be a red herring for the main underlying problem the OP is experiencing. A positive result from a fuel flow return only tells you that the fuel pressure and volume are good. A negative test tells you you need to look further which is why I bring up testing the actual fuel pressure, a simple and inexpensive procedure.

 

Back to the red herring. Consider if the fuel return flow test is negative so the fuel pump is replaced only to find the problem is not solved.

 

When everything is apart and your trying to track down a problem that has multiple possible causes it would seem to me to be in your best interest to take a little extra time to find out precisely what is going on with the different systems involved.

[roger 04 rt]

 

If the regulator is functioning correctly (highly likely) and the pressure was 40 psi, there would be no flow in the return line.

 

Interestingly, even if the fuel pressure regulator was 38 psi, the bike would run perfectly fine if the pump, fuel filter and hoses in the tank were working. The reason is that a 15% drop in fuel pressure only reduces injector fuel delivery by a little under 7%. The Motronic, using Closed Loop Mixture Adaptation, will correct the entire fuel map just fine.

 

The part of mine you put in red is in agreement with what you are stating.

 

There were two competing lines of reasoning.

--One line of debugging said rule in/out a fuel issue by checking return volume.

--The other said check fuel pressure to achieve that end.

 

The difference of approach led to some arm wrestling among us.

 

Either or both tell you something. But the return volume test is faster, takes no gauges or special equipment and is more comprehensive.

 

I'm clear on what you are saying, but the point I was making is that the fuel volume return test does not take into account a faulty pressure regulator, but more importantly it could be a red herring for the main underlying problem the OP is experiencing. A positive result from a fuel flow return only tells you that the fuel pressure and volume are good. A negative test tells you you need to look further which is why I bring up testing the actual fuel pressure, a simple and inexpensive procedure.

 

Back to the red herring. Consider if the fuel return flow test is negative so the fuel pump is replaced only to find the problem is not solved.

 

When everything is apart and your trying to track down a problem that has multiple possible causes it would seem to me to be in your best interest to take a little extra time to find out precisely what is going on with the different systems involved.

 

Hi Eddd, Practically speaking, the low fuel volume test really can't be red herring. If you have low/no return volume, there is something in the tank that needs to be fixed.

 

On the other hand, somewhat low fuel pressure can be both a red herring (a bike will run fine at low pressure provided there is sufficient return volume) and non-diagnostic (normal pressure will exist right up to the point of internal hose rupture, even though half a pump's capacity is leaking through in-tank hoses).

 

I don't disagree with your view that measuring fuel pressure might be useful added information. But the cost/time/value of the test, when debugging the symptoms the OP posted, probably isn't warranted.

 

Below is my kit for testing pressure and volume. The return volume hose is simple, and the return volume test can be done without it if you hold the check valve in.

 

To test fuel pressure effectively you have to cut a hose and insert a T or have a pressure gauge with QDs. I've got one but it's costly and takes some construction. This is why I don't go there first.

 

 

 

 

[JamesW]

Hi Ed, As Roger points out a fuel volume test is the best place to start and will tell most if not all of the story. I think it highly unlikely, but not impossible, that the fuel pressure regulator could ever actually fail. The regulator could, I suppose, become partially clogged which is also unlikely, imo. So, go with the fuel volume test as this gives the most info in a simple economical way without over complication.