Intermittant fault... Engine dies like it runs out of fuel.
Discussion
A shiny penny to the man who can diagnose my Honda CBR 600 FX (1999) - The most reliable and best bikes ever.
The bike runs sweet as a nut, then the revs begin to fall, the throttle becomes unresponsive, and it dies completely over the course of about 20 seconds. It's progressive so not particularly dangerous, and seems more like it has run out of fuel to me. It does this very irregularly though, say four times in 4,000+ miles. But it's just frustrating wondering if it will die.
It's been to what I would consider a good garage and he's just told me he's stumped like me, but has been very good about the bill as a result.
-Alternator, regulator, battery = fine.
-Fuel pump, injectors etc, = fine.
-No vaccuum from aftermarket fuel cap.
-All carb, fuel, air lines checked.
-Valve timing and clearances just done.
-All filters including pre-air are new.
-Exhaust is leaking, and I'm going to balance the carbs after this.
I'm a bit lost here. Fuel and spark seem fine and that's all I know to do. I've ruled out kill switches, side stand switches etc. on the basis that they kill the ignition and this is a slightly drawn out death. My mate has suggested ECU drivers, but I've only seen that on cars and they were a lot more noticeable.
Carbs I know little about in all honesty, but would not have expected to have intermittent faults in combination with running so well. They've been off and the pipes and seals examined, but not taken apart.
This sounds stupid, but I'll say it anyway, it was an absolute f
ker to get into neutral when it died.
I'm stumped. I can't even throw parts at it!
The bike runs sweet as a nut, then the revs begin to fall, the throttle becomes unresponsive, and it dies completely over the course of about 20 seconds. It's progressive so not particularly dangerous, and seems more like it has run out of fuel to me. It does this very irregularly though, say four times in 4,000+ miles. But it's just frustrating wondering if it will die.
It's been to what I would consider a good garage and he's just told me he's stumped like me, but has been very good about the bill as a result.
-Alternator, regulator, battery = fine.
-Fuel pump, injectors etc, = fine.
-No vaccuum from aftermarket fuel cap.
-All carb, fuel, air lines checked.
-Valve timing and clearances just done.
-All filters including pre-air are new.
-Exhaust is leaking, and I'm going to balance the carbs after this.
I'm a bit lost here. Fuel and spark seem fine and that's all I know to do. I've ruled out kill switches, side stand switches etc. on the basis that they kill the ignition and this is a slightly drawn out death. My mate has suggested ECU drivers, but I've only seen that on cars and they were a lot more noticeable.
Carbs I know little about in all honesty, but would not have expected to have intermittent faults in combination with running so well. They've been off and the pipes and seals examined, but not taken apart.
This sounds stupid, but I'll say it anyway, it was an absolute f
ker to get into neutral when it died. I'm stumped. I can't even throw parts at it!
Edited by Prof Prolapse on Thursday 19th February 14:04
RemaL said:
U do have fuel in it?
Yes. :Pbass gt3 said:
Sounds like a form of fuel starvation. Carb'd or injected??
Look for kinks in the fuel lines, maybe a fuel filter in the tank you've missed???
Carbs, that was my first thought. According the Honda manual I have there's only one fuel filter. All lines have been checked. I even had the mechanic inspect the full system today (along with the charging system) to make sure I wasn't being stupid. Look for kinks in the fuel lines, maybe a fuel filter in the tank you've missed???
rat840771 said:
This maybe a stupid question, but does it die/cut out when the fuel in the tank is at a lower level? I am not sure how these fuel tanks work but if it is gravity fed maybe the feed slows down as the tank get low on fuel?
I'm clutching at straws, there's nothing stupid at this stage I don't think. Tank was about 1/4 full I think, previously has done it half full. Unsure on two occasions prior. I had an issue with my VFR750F where it was fine if run gently. If you rode it fast it would exhibit the signs of fuel starvation before finally packing up or ride slowly and it would (after a while) fine again. If it stopped then prime it and restart and it was fine (if ridden gently).
Anyway, it turns out that inside each carb above the needle valve was a tiny fuel filter and each one of them was clogged so the fuel pump couldn't quite fill it quick enough. Cleaned the filters (basically just remove each of the needle valve seats and the filters were a little cap on top) and it ran sweet as anything.
Worth checking to see if the CBR6 has similar filters...
Anyway, it turns out that inside each carb above the needle valve was a tiny fuel filter and each one of them was clogged so the fuel pump couldn't quite fill it quick enough. Cleaned the filters (basically just remove each of the needle valve seats and the filters were a little cap on top) and it ran sweet as anything.
Worth checking to see if the CBR6 has similar filters...
I'm going to say in line fuel filter if there is one, or in tank filter.
Loads of owners on a Suzuki bandit forum have had a similar problem, tried all the expensive stuff like carb cleaning, synch etc and 9/10 it's been a dodgy aftermarket fuel filter or the standard one has been blocked with crap.
Check for rust in the tank too which may be getting through and choking things.
Loads of owners on a Suzuki bandit forum have had a similar problem, tried all the expensive stuff like carb cleaning, synch etc and 9/10 it's been a dodgy aftermarket fuel filter or the standard one has been blocked with crap.
Check for rust in the tank too which may be getting through and choking things.
StuB said:
I had a similar sounding problem.
Mine would feel like it was running out of gas, but what fixed it was the tank breather. The old pipe was not letting air in as I used fuel & it caused starvation, worse from a full tank, as the vacuum builds up quicker.
I would check this first.Mine would feel like it was running out of gas, but what fixed it was the tank breather. The old pipe was not letting air in as I used fuel & it caused starvation, worse from a full tank, as the vacuum builds up quicker.
StuB said:
I had a similar sounding problem.
Mine would feel like it was running out of gas, but what fixed it was the tank breather. The old pipe was not letting air in as I used fuel & it caused starvation, worse from a full tank, as the vacuum builds up quicker.
This was actually my best idea last year, but I was damned if I could find a problem. I discussed this with the mechanic but not sure exactly what he checked in this regard.Mine would feel like it was running out of gas, but what fixed it was the tank breather. The old pipe was not letting air in as I used fuel & it caused starvation, worse from a full tank, as the vacuum builds up quicker.
I'll check again.
Alex@POD said:
You say it happened 4-5 times over a lot of miles, what did you do to restart the bike after it died those other times? Did it restart of its own accord a little while later, or straight away?
I put it in neutral. Then it took between ten and thirty minutes but difficult to remember. As for exactly what I did regarding switches and gears, I am unsure.What I am sure of though and had forgotten, is when I pushed the start button the lights were on but, no turning over, I don't even recall the click. If the battery and charging system is fine (that is independently confirmed) that means its probably a good idea to assume I'm talking s
t about it dying slowly and go back the sidestand/kill switch.Right this is my current list (in no particular order);
1) Fuel pump contacts
2) Killswitches/Sidestand switch
3) Breather hoses (again)
4) Fuel pump relay
5) Wiring loom on subframe.
6) Earths (as per 5).
7) Fuel filter (this is actually from late last year but will check all the same).
8) Will fill her up and see if I can make it happen again (before checking hoses) to rule out vacuum.
1) Fuel pump contacts
2) Killswitches/Sidestand switch
3) Breather hoses (again)
4) Fuel pump relay
5) Wiring loom on subframe.
6) Earths (as per 5).
7) Fuel filter (this is actually from late last year but will check all the same).
8) Will fill her up and see if I can make it happen again (before checking hoses) to rule out vacuum.
moanthebairns said:
I read this then came back to it so sorry if its been mentioned or sounds stupid but here goes.
Have you drained and cleaned the tank, could it be some crap is swirling around inside that every once and a while finds itself blocking the outlet
Worth a go. I'll check the stopcock whilst I'm doing it.Have you drained and cleaned the tank, could it be some crap is swirling around inside that every once and a while finds itself blocking the outlet
moanthebairns said:
I read this then came back to it so sorry if its been mentioned or sounds stupid but here goes.
Have you drained and cleaned the tank, could it be some crap is swirling around inside that every once and a while finds itself blocking the outlet
<PH Standard>Have you drained and cleaned the tank, could it be some crap is swirling around inside that every once and a while finds itself blocking the outlet
I don't normally agree with anything MTB posts but...
</PH Standard>
Sounds possible, I used to drive a coach that did the same when a rubber glove dropped in the tank covered the pick up.
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