Starts but won't run

Sgt80

VIP MEMBER
Joined
Nov 21, 2017
Messages
135
Country flag
Starting issues have been beaten to death in previous threads but I couldn't find one specific to my present situation. So here goes...May 2014 built bike. All the usual upgrades with sensors, coil, plugs and wires done. I even replaced all the relays recently with the Honda branded ones which was prompted by intermittent fuel pump issues. The fuel pump comes on with authority each and every time now after the relay replacement. I keep the bike on a battery maintainer all the time.
I start the bike last Saturday as I had to evacuate my home due to the recent Northern California fire. It starts right up, needs a little of the usual throttle input before it warms up. Rode it about 5 miles. No problem. It was then parked out in the open, day and night, for 5 days. Came back to retrieve it and it started but would not idle even with throttle input. I managed to get it home even though it would stall at every stop. Now I can't even get it to stay running with throttle input. It just bogs down after a couple of seconds of running even with throttle input. When it does conk out it will die with a very loud compression "huff" and once a very light cloud of white smoke appeared on the right hand side when it died.
I checked the plugs, checked all the usual bolts/screws for air leaks, checked the air filter, checked all the sensors to make sure they were not loose and cleaned the area around the kick stand sensor.
This bike has NEVER behaved this way before.
Thank you gentlemen for any help or suggestions!
 
Did it get wet during those 5 days, maybe water ingress somewhere? I'd go for easy options first (1) check electrical connections (especially to the idle control motor) (2) change plugs.

Cheers,

cliffa.
 
How old is the fuel?
Did the fuel get any water in it?
Are the plugs or spark plug wires wet?
I’d remove the idle control valve and check it.
We’re the plus wet with fuel when you removed them?
Was it stored in a secure area or open to the public?
 
Lambda sensors ? , have u linked them out with those resistors ( for the aprillia 1000) these are what are whole bunch of us have fitted with great success
 
Came back to retrieve it and it started but would not idle even with throttle input. I managed to get it home even though it would stall at every stop. Now I can't even get it to stay running with throttle input. It just bogs down after a couple of seconds of running even with throttle input.

You managed to get it home.
Understood that it stalls at stop lights while idling, but how was the engine performing while underway on the road headed home?
Lurching, coughing, running erratically, or operating normally?

The loud Huff could simple be the engine stalling before the exhaust valve opened and relieved the cylinder compression.
White smoke may be un-burned mixture expelled from the cylinder.

If the bike ran OK when you evacuated your home originally, I doubt after only 5 days that fuel is your problem.
If the bike was rained on or humidity got to the airbox temp sensor this could screw with your ECU's operation.
 
If it rained and that is IF . California doesn't get a lot of rain . The air box air temp sensor ? Make sure the battery is fully charged .
 
SgtUSAF80
I would check the throttle position sensor - I had similar when mine was playing up. Explanation from technician was that even on startup the TPS is not operating with any input so puts too much fuel in the throttle bodies and literally chokes the engine!
The white puff of smoke could have been unspent fuel. Anyway, worth an investigation.
John
 
Thanks so much for all the great input! There was no rain and the bike never got wet. The fuel had Stabil added. The plugs were dry. They were the NGK Iridium plugs (CR9EIX) and they had a light, even coating of carbon. I pulled them and installed the original plugs that came with the bike. The gap was correct and they were clean but it made no difference when I tried to get the bike running with them vs. the Iridium's. I pulled the throttle position sensor. The wire connection is clean and the throttle body spindle that interfaces with the back of the sensor moves freely. When I rode the bike home it did "lurch, cough and run erratically". I also pulled both Lambda sensors. They were clean with only a slight amount of carbon coating. The bike was in a secure area the whole time so nobody could have messed with it.
Any other suggestions or ideas? Thanks again!!
 
Last edited:
This is the part that sucks about EFI systems.
Could literally be anything at this point.
If you had an OBD-II scanner you could connect to the ECU and see if there are any fault codes.
That would narrow down the search path for you.
Otherwise it's - try something, try something else, repeat....
 
Of course, I have NO clue what is wrong with your bike,...

WTBS, You are using a battery tender when your bike is parked. As good as they are for making a battery last longer because they maintain a higher resting state of charge, they can also mask charging and electrical draining problems if you take relatively short rides in between plugging your bike back into the "tender". If low voltage to the ECU is the problem because you were off the battery tender for a few days, then putting the bike on the battery tender overnight should cure the problem temporarily if it's related to charging... just my $.02
 
I pulled the throttle position sensor. The wire connection is clean and the throttle body spindle that interfaces with the back of the sensor moves freely
I would still look towards the TPS setup. For me, it wasn’t the sensor but the wire that had cracked/split. It is vulnerable as it originates near the headstock - unusually on the non throttle side! The symptoms you describe are exactly the same as I had until it died completely and then started but would not run eventually starting and cutting out within seconds (sound familiar?)
Do you have the workshop manual.
John
 
I’d still drain the tank and add new gas.
As mentioned earlier it could be the throttle position sensor or o2 sensors. Without a scan tool it’s hard to say.
If it ran ok the previous time you rode it, I doubt it’s a sensor. But I seen stranger things in the past on the cars I work on.
Do you have a fuel pressure gauge to test psi reading?
Did you check the color of spark when you pulled the plugs? Yellow is weak, blue is strong.
Are you 100% certain you have a minimum of 12 volts when it’s idling? 13.5+ at RPM.
Can’t hurt trying fresh gas.
 
Of course, I have NO clue what is wrong with your bike,...

WTBS, You are using a battery tender when your bike is parked. As good as they are for making a battery last longer because they maintain a higher resting state of charge, they can also mask charging and electrical draining problems if you take relatively short rides in between plugging your bike back into the "tender". If low voltage to the ECU is the problem because you were off the battery tender for a few days, then putting the bike on the battery tender overnight should cure the problem temporarily if it's related to charging... just my $.02
I appreciate your theory and taking the time to post it. I have a Shorai battery and maintainer. It was hooked up again when I returned on Thursday. Tried to start the bike on Friday. Back on the maintainer and tried again yesterday. Starting the bike is no problem. It runs great for about 2 seconds!
 
I’d still drain the tank and add new gas.
As mentioned earlier it could be the throttle position sensor or o2 sensors. Without a scan tool it’s hard to say.
If it ran ok the previous time you rode it, I doubt it’s a sensor. But I seen stranger things in the past on the cars I work on.
Do you have a fuel pressure gauge to test psi reading?
Did you check the color of spark when you pulled the plugs? Yellow is weak, blue is strong.
Are you 100% certain you have a minimum of 12 volts when it’s idling? 13.5+ at RPM.
Can’t hurt trying fresh gas.
Thanks voodoo. No gauge but I'll check the spark. I can't get the bike to idle at this time of course but the voltage on the display reads 12.6/12.7 when I turn the key on.
 
I would still look towards the TPS setup. For me, it wasn’t the sensor but the wire that had cracked/split. It is vulnerable as it originates near the headstock - unusually on the non throttle side! The symptoms you describe are exactly the same as I had until it died completely and then started but would not run eventually starting and cutting out within seconds (sound familiar?)
Do you have the workshop manual.
John
Thanks John. I'll work on your suggestions and yes, I have a workshop manual.
 
You will need to gain access to the ECU main harness plug and the TPS end to ohm that out. Also , the tip over sensor is in that TPS circuit. I think you should disconnect the battery before you take those plugs off for ohm continuity testing . You can cheat the tip over sensor with resistors . Look that up in the archives.
 
My dads friend had his coil bolt come loose. A few weeks after he swapped it out. The bolt makes the ground. Similar symptoms .... sort of. These bike vibrate a lot.
 
Starts but won't run

Re the lamda sensors , they might look clean but can be faulty, get those resistor plugs to blank them off , I left mine connected on the down pipes , but plugged them off under the tank, there is a “ lamda delete” thread to get the eBay seller,I’ll dig out my pics & put them on here , it’s the best affordable value for money upgrade, mine wouldn’t run under 30mph properly with faulty lamda s,had to rev it , cough ,splutter,back fire, nasty fuel smell , they were replaced under warranty,but I still fitted them the year after , completely smoothed out the ride , no judder or hesitation or cutting out
https://www.accessnorton.com/NortonCommando/the-lambda-delete-thread.25055/
 
Last edited:
Back
Top