Engine stuttering

Joined
Oct 20, 2007
Messages
35
Location
Mexico City
Bike
2003 St1300 abs
Hi all,

I'm wondering if you can take a few minutes to help me out with some ideas to find an intermitent problem with my 2003 ST1300. Maybe a fault finding sequence. Pointers.

The problem is:
Engine sometimes starts surging, reving and slowing like crazy when running: i.e. the engine does not rev uniformly but decelerates and accelerates in cycles. At idle speed the engine is OK, but when trying to move forward it fails unless I give it a lot of gas and use the clutch to prevent it from totally ruining the shaft drive from the sudden surges or throwing me off the road. This progresses until it's impossible to move. Engine will oscilate, reving up and stalling. You can feel the stress on the shaft drive. If the engine is left to idle however it's fine again. If the bike is left to cool thoroughly, it's fine.

I can point out the following whigh may help in getting pointer from you:

  • The water temperature shows the perennial 3 bars. Engine does not seem to tell me it's hot, though it can almost burn in the groin.
  • Usually we've been riding for a while and often in stop and start or slow traffic.
  • It happens only occasionally and after longer rides, say more than two hours on the bike.
  • There is sometimes a smell of gasoline.
  • Bike will be back to normal if left standing (engine off) for a long while.
  • Problem dissappears if bike is left overnight.
Some recent history of previous problems and farkles:

Where would you look first?

I'm guessing it's flooding. But why? Would you blame the TurboTom FPR?

Many thanks for any pointers.

Anyone visiting Mexico?
 
Last edited:
IMHO, you need a new fuel pump.

I just replaced mine for same symptoms. It only happens when fuel tank has hot-soaked, causing severe surging.
Best price I could find was from ronayres.com for $320. The maint manual also recommends replacing the large-diameter hose and clamp from the lower tank to the upper tank.

There's only two choices; ignition coils or fuel pump. Since both coils would have to fail at the same time, that was the unlikely choice.

When you open up the tank, be prepared to draw out all of the gas with a hand-pump (very hazardous, no sparks), and wipe the bottom of the tank clean with something that is lint-free (like fabric-softener sheets). The tank will have dirt in it.
 
This fuel pump culprit seems probable. Maybe I'd have to remove and test it first though. Think there's a routine for that in the shop manual.

ronayres.com seems to sell advertures not parts though. Would that be another supplier you're thinking of?

IMHO, you need a new fuel pump.

I just replaced mine for same symptoms. It only happens when fuel tank has hot-soaked, causing severe surging.
Best price I could find was from ronayres.com for $320.
 
This bike is allways at high altitude. I've been watching carefully but the problem has presented at far lower altitudes than where it's usually at and also at higher. Doesn't seem to be related to altitude

Rolando, is the problem more pronounced at higher altituded?
 
Last edited:
Anyone with similar situations should read the full more than 100 message strong thread "Throttle problem":

https://www.st-owners.com/forums/showthread.php?t=25663&highlight=surge

Brilliant exchange. Real educational read. Very knowledgeable people participated back in 2005.

In my case it all seems to point to the fuel pump. There is a sugestion to make the ventilator start up more often, but I haven't understood that yet or how to do it. But I will try that before changing the very expensive fuel pump, though it seems I will probably have to anyway. Terrible problem in very hot weather. Surges like crazy. Can't be left in the middle of the sierra next tripo.
 
Anyone with similar situations should read the full more than 100 message strong thread "Throttle problem":

https://www.st-owners.com/forums/showthread.php?t=25663&highlight=surge

Brilliant exchange. Real educational read. Very knowledgeable people participated back in 2005.

In my case it all seems to point to the fuel pump. There is a sugestion to make the ventilator start up more often, but I haven't understood that yet or how to do it. But I will try that before changing the very expensive fuel pump, though it seems I will probably have to anyway. Terrible problem in very hot weather. Surges like crazy. Can't be left in the middle of the sierra next tripo.


Make sure the hoses under the main tank are not kinked or miss routed. I've heard you can get weird issues from that.:eek:4:
 
An exchange with a very knowledgeable friend from my bikers list here in Mexico has offered some great ideas I'd like to put forth to anyone following this thread.

The aforementioned exchange is in spanish, but I'll write up the conclusions and copy the text bellow, just in case you want to practice your spanish:

  1. Although we agree the gas pump is the most likely culprit, I'm still asking myself if it could not be one of the coils. This would make two pistons fail and it could be intermitent and related to temperature. So I ask, is there a way to test the coils with a multimeter to rule them out as the source of the problem? Would it be impossible because the coils would have to be very hot to present the problem even in the eyes of the multimeter?
  2. Could the temperature sensor which starts the fan be at fault? I think not, because the perennial three bars are allways there and so the water temperature would seem to be OK, even though the engine gets real hot and the metals bellow the upper tank and where my groin is get really hot. What would you think?
  3. Would it be possible to take out the pump and filter and isolate electrical contacts there? I'm figuring it might not be the pump that is wrong, because I'm thinking it would fail completely, rather than intermittently, whereas the electrical contacts right there might be more likely to fail intermitently and that could be linked to temperature. But what could be used to better isolate electrical contacts inmmersed in fuel?
  4. Could a solution be in changing or cleaning the gas filter, rather than the whole pump mechanism? Would a fault like this be something a clogged fuel filter could provoke?
  5. Or would the best course of action be to forget everything else, just cough up the money and change the gas pump and everything it comes with for the whopping US$435 plus taxes and postage. (http://partsfinder.onlinemicrofiche.com/speedsupplies/Honda_OEM/HondaMC.asp?Type=13&A=377&B=51) (The risk of this expense and wait and in the end the problem being elsewhere and the ensuing frustration is what bothers me though.)
Any input on this diagnostic would be very welcome.

Many thanks to anyone who reads down to here.

Ride safe... ride often... ride hard.

Dr. Rolando Montano

Estimado Carlos,

Gracias por tu an?lisis. Absolutamente docto. A la altura del mejor de la lista que yo opino viene siendo el de SCOOTER en el No. 81 de "Throttle problem" que explica sobre los tipos de circuito de chispa con chispa perdida en estas motos.

Super claro tu diagn?stico. Estoy enteramente de acuerdo.

Sin embargo y siendo que la falla es como una repentina baja de petencia que se repite en el motor cuando esta muy caliente, todav?a me pregunto si pudiera ser una bobina y su efecto en dos pistones: ?Crees? Una sola bobina, dos pistones sin corriente, falla que se repite en alta temperatura del motor... Se puede distinguir la falla en el video que coloc? CCRYDER en el post No. 32 de "Throttle problem" (https://www.st-owners.com/forums/attachment.php?attachmentid=21172&d=1186803567). Sin embargo, creo como tu que es m?s probable lo de la car?sima bomba de gasolina, pero ser?a importante descartar.

Por otro lado, tambi?n me pregunto cual ser?a el car?cter de la falla en el conjunto de la bomba y filtro de gasolina, si ese fuera el caso, como estamos bastante convencidos los dos. La alta temperatura de la gasolina, ?tender?a a provocar un problema en la conexi?n el?ctrica dentro del tanque de gasolina? Si fuese as?, ?ser?a entonces posible sacarla, tratar de aislar mejor las conexiones para colocarla nuevamente? (Cosa dif?cil, porque el aislante estar? sumergido en gasolina.) ?C?mo es que t?picamente puede fallar un motor el?ctrico, enfriado por inmersi?n en gasolina, cuando la gasolina esta demasiado caliente? Yo pensar?a que el motor t?picamente fallar?a por completo, antes que intermitentemente y que son en realidad los contactos el?ctricos los que m?s frecuentemente suelen fallar intermitentemente y tambi?n cuando estan sujetos a grandes variaciones en temperatura. ?Pudiera entonces ser pertinente solamente cambiar ese filtro de gasolina que explicas que no es filtro en realidad? (Esa pieza cuesta US$46 contra US$435 de la bomba y conjunto.)

Obviamente estoy aqu? explorando en favor de arreglar en lugar de pagar la car?sima bomba de gasolina y conjunto de filtro completos. Tambi?n para tratar de no gastar en balde. Pero tambi?n por puro deporte intelectual en el que creo me acompa?as y agradezco eso.

Otra cosa que me pregunto y te agradecer?a tambi?n tu opini?n, siendo que veo te interes? el reto diagn?stico (al estilo Dr. House) es considerar la cuesti?n de lo mucho que se esta calentando la gasolina y la moto. Se sabe que esta moto funciona muy caliente. En la entrepierna ya me estaba casi tatemando. Alberto constat? al tacto la temperatura de los metales de los costados, abajo del tanque.

Tal vez el sensor de la temperatura del agua debiera cambiarse o probarse, para ver si esta en efecto dispar?ndose a tiempo. Sin embargo, siendo que la temperatura del agua marca sus perenes tres rayas, ex?ctamente al 50% de la m?nima y m?xima temperaturas, esto indicar?a que por muy caliente que la siento, La Nena ella en realidad se siente perfectamente en su temperatura normal, y ning?n fin ?til tendr?a andarle buscando como bajarle la calentura si esa es su naturaleza.

Sobre conseguir piezas para cambio, creo que con mucho y lo car?simo de la bomba, terminar?a por ser m?s barato simplemente cambiar la bomba, especialmente si la alternativa fuera entregarles La Nena a una agencia aqu?, donde posiblemente nunca llegaran a los sesudos an?lisis diagn?sticos que personas como tu o SCOOTER del post No. 81 en "Throttle problem" pueden ofrecer. Yo creo que mas bien acabar?an hech?ndola a perder, como sucede cuando una mujer as? acaba en manos de ineptos, sin nunca comprender, aceptar y vivir con su caliente naturaleza y los verdaderos motivos de sus relinchos y fallas.

En resumen, te pregunto si considerar?as pertienente:

  1. Probar las bobinas con un mult?metro en cuanto a resistencia, si es que eso pudiera llegar a identificar la falla en ellos de existir.
  2. Probar o cambiar el sensor de temperatura del agua.
  3. Sacar la bomba y conjunto, checar las conexiones y aislar los cables y ver si con eso se resuelve. (Pero ?con qu? tipo de aislante?)
  4. Cambiar o limpiar el filtro de gasolina.
  5. Olvidarme del sensor de temperatura del agua o cualquier otra posibilidad y omprar y cambiar la bomba de gasolina que viene con todo y el filtro. (http://partsfinder.onlinemicrofiche.com/speedsupplies/Honda_OEM/HondaMC.asp?Type=13&A=377&B=51)
(Ya s? que para la mayor?a en esta lista la ?ltima alternativa seguro es la l?gica, pero aparte del costo, si al final resulta que no es la bomba, esta tambi?n la frustraci?n del gasto superfluo, m?s la espera en d?as moteros como estos.)

Que tengas excelente d?a Carlos y todos en la lista tambi?n.
Si gustan leer sobre este asunto de diagn?sticos y calenturas:
https://www.st-owners.com/forums/showthread.php?p=1004475#post1004475
https://www.st-owners.com/forums/showthread.php?t=25663&highlight=surge


Dr. Rolando Monta?o Fraire
rolando.montano@gmail.com
www.rolandomontano.info
El 26 de abril de 2010 20:11, Carlos Mart?nez <cmartinez@mototourbmw.com> escribi?:
Hola Rolando, le he dado una estudiadita a tu problema en el foro que nos mandaste y te quisiera hacer unos comentarios:
1.- El ?nico modo que yo s? para hacer que el motoventilador entre m?s r?pido (en algunos autom?viles) es cambiando el sensor interruptor del motoventilador que va en contacto directo con el anticongelante, que en algunos modelos (de autos) viene en tres graduaciones diferentes. No s? si para tu ST 1300 tambi?n exista esa posibilidad, yo creo que no.
2.- Aunque lograras hacer que el motoventilador entrara digamos a unos 85 grados cent?grados (normalmente entran por ah? de los 95 grados), no lograr?as bajar la temperatura de la bomba de gasolina, al menos no en forma significativa y tangible.
3.- Estoy de acuerdo con alguien del post que dice que no hay m?s que bomba ? bobinas, y tambi?n estoy de acuerdo con ?l, de que es muy dificil que fallen las dos bobinas simultaneamente.
4.- Estoy casi seguro que tu problema es tu bomba de gasolina, a menos que tu moto tenga alg?n tipo de filtro de combustible, y este, est? taponeado de suciedad, (creo que la ST 1300 ya no lleva propiamente un filtro de alta presi?n, sino una especie de tam?z en el mismo conjunto de la bomba el?ctrica) checa tu manual de servicio.
5.- No creo que te sirva de mucho llevar a cabo las pruebas de presi?n de combustible que vienen en tu manual de servicio, ya que las mismas deber?an de hacerse en el momento que se presentara el problema, si no hay problema en el momento de la prueba, vamos a decir de presi?n y/o entrega de volumen en altas rpm's, te vas a quedar en las mismas.
6.- No s? si alg?n distribuidor en el D.F. tenga scanner para ver si hay (y cu?les) c?digos de falla (s) que te pudieran inclinar m?s hacia la misma bomba, los debe de haber, valdr?a la pena checar y ver si no te cobrar?an mucho por sacar la lista de c?digos de falla.
7.- En resumen, el tipo de falla, apunta directamente a tu bomba de combustible, que no se me hace cara......... se me hace car?sima, por lo que quiz? valdr?a la pena de que explores a alg?n "Stealer" en el D.F. A la mejor hasta tienen alguna de prueba.
Te mando muchos saludos, y estar? atento al resto de la convalescencia de La Nena.
Carlos Mart?nez E.

On Mon 26/04/10 5:55 PM , Rolando Monta?o Fraire rolando.montano@gmail.com sent:

 
Are any codes being thrown from the ECU? I would think mis-firing coils or even a possibly bad fuel pump would set some kind of a code. I've no experience with this myself - so maybe not.

IMO fuel filter would also be a consideration.

:06biker: :06biker: :06biker:
 
Thanks. You're right, reading the codes is probably the first thing that needs doing. Must learn how to without the computer. Probably need to do it when it's failing. Will read up on this. Thanks again.

Really neat trip logs on your site.

I've mostly pictures, but in case you want to visit:
Picasa photo albums: http://picasaweb.google.com/rolando.montano
Blog: http://viajes-en-moto.blogspot.com/

Rolando.
 
There are several fuel pumps available on eBay right now. Would be a less expensive alternative than buying retail.

eBay link
 
Followed the wiki guide to look at fault codes. Started the bike with the side stand. FI light momentarily lit, simultaneous with the fuel pump, went off and never came on again at all. Engine ran until the temp got to the perennial 3 bars. According to the Wiki instructions there are no faults stored. Strange, considering the violent surging when very hot.

I did check the used fuel pumps and I think that will be the way to go. Many many thanks for the pointer. A fuel pump from a 2006 ST1300 with only 6500 miles seems like a good candidate.

Is there any difference between a 2003 and a 2006 ST1300 fuel pump?

Or can I get the 2006 model year fuel pump to replace mine. This bike is 2003 year. The fuel pump I'm considering buying is from a 2006 year ST1300.

Thanks again for all your help.
 
Is there any difference between a 2003 and a 2006 ST1300 fuel pump?

Or can I get the 2006 model year fuel pump to replace mine. This bike is 2003 year. The fuel pump I'm considering buying is from a 2006 year ST1300.

Thanks again for all your help.

Looking through the Online Parts Fiche reveals that the part number 16700-MCS-G01 is used on 2003 through 2007 model years. The -G01 version replaced the -G00 version originally used on 2003 ST's. I would have no problem using the 2006 pump on your 2003.

2008 and 2009 STs call out the part number 16700-MCS-G02. I'm not sure what functional difference there is between those two part numbers.
 
Thanks yet again Scooter. :)

It looks like I'll have to live with choosing cool hours and locations until the fuel pump arrives. We're thus planning a trip out this Sunday 6am to the mountains. We're taking a book to read while the bike cools if it acts up.
:04biker:

Have fun. :)

Looking through the Online Parts Fiche reveals that the part number 16700-MCS-G01 is used on 2003 through 2007 model years. The -G01 version replaced the -G00 version originally used on 2003 ST's. I would have no problem using the 2006 pump on your 2003.

2008 and 2009 STs call out the part number 16700-MCS-G02. I'm not sure what functional difference there is between those two part numbers.
 
Looking through the Online Parts Fiche reveals that the part number 16700-MCS-G01 is used on 2003 through 2007 model years. The -G01 version replaced the -G00 version originally used on 2003 ST's. I would have no problem using the 2006 pump on your 2003.

2008 and 2009 STs call out the part number 16700-MCS-G02. I'm not sure what functional difference there is between those two part numbers.


I doubt there's any functional difference. The following may help:
http://www.vsource.org/VFR-RVF_files/BHondaPartNumbers.htm
the right-most 0 vs. 1 vs 2 supposedly only designates which subcontractor made it for Honda. All are "G0" versions, meaning fabricated to the same specs and prints.

As an aside...
"MCS" represents Honda's Product Code Number (PCN) for the ST1300. That 3 digit code represents the motorcycle for which the part was first designed. But as they reuse as many parts as possible, there are other 3 digit PCN parts in use on every bike such as the ST1300.

:shrug1:
 
Generally surging and sputtering at higher rpm/load is fuel starvation. Typically ignition drop out due to coil issues results in miss-fires as opposed to surging. When you are cruising along at 3-4 thousand rpm a single drop out might not be noticed. In my experience the drop out would extend a few cycles and would feel more like a miss than a surge. One key is the fact that the engine will idle and the engine acts up when more fuel is required. A marginal fuel pump, faulty inlet line, partially blocked fuel filter or fuel regulator issues can mimic vapor lock that might explain the surge after heat soak. I am going with the crowd on fuel pressure/volume related issues. Higher temperature and high altitudes can cause fuel to boil. When that happens surging can occur. Higher fuel pressures like high pressure radiator caps discourage this from happening. I always set fuel pressures at the top of the envelope. I hope that all these threads are helpful. Please keep us posted. One more thing, include tank vent check while you are at it.

Just thinking out loud!
 
Many thanks to all who helped out to diagnose this. Especially pointing out the similar fault with video indicated above.

I got both coils and fuel pump from eBay ad US$99 fuel pump and US$40 for the coils. Perfect shape, like new from a 06 model with 8k mikes it seems.

Installed the fuel pump first: Everything is now working perfectly. Some great rides to Cuernavaca and the area around the volcanoes. Various altitudes and temperatures. Long rides.

I'm still uncertain what part of the fuel pump assembly was at fault, since I replaced fuel pump and fuel filter as they came, all together. It took about half an hour to do the task. I will see if there is a way to test them.

Now I have an extra pair of coils for the unlikely event they fail.

Thanks again. Enjoy safe fun riding.

:06biker:
 
Back
Top Bottom