efi 125 starts then dies.... - Page 3

thumpa · 02-14-2023, 12:09 PM

hello!

having banged my head against the wall for over a week trying to fix this issue, today i found a fault with the CLUTCH LEVER SWITCH!

(the switch that stops engine starting if clutch disengaged).

it is permanently in a closed circuit, regardless of whether in or out.

disconnected it and engine starts and, even better, stays started!

i don't know what made me check it - the fact the engine started made me think it could not be that or it would not start at all. still trying to work out why. almost like a capacitor is discharging.

anyway thanks to everyone who offered assistance.

great forum.

**JerryHawk250** · 02-14-2023, 01:13 PM

Glad to see you figured it out. That's strange that you had any spark at all. If there were no spark the safety switches would of been the first thing I would of checked.

thumpa · 02-14-2023, 01:25 PM

it is indeed very strange jerry but it is the fault.

weird as weird can be!
cheers!

Dustoff42 · 02-14-2023, 10:16 PM

Isn’t it annoying when it was such a simple thing? You seem to know the bike well though. Good job figuring it out. I have had those moments where you think out of the box for a millisecond and it solves everything.

thumpa · 02-15-2023, 03:09 AM

thanks dustoff!

i can safely say i know the bike a lot better after the last week!

i know where every damn wire goes and the schematic diagram for the electrics is burned into my retinas!

i shall almost miss this forum now.

until the next time.

thumpa · 02-22-2023, 06:31 AM

hello chinariders! a quick update ....

that was not the cause of my problem! the problem started again about half a mile from my house, luckily i was uphill from where i live which is very hilly.
the clutch switch issue was a problem but on only in that it meant i could turn over the engine in gear and with clutch in or out (but it was causing an earth issue there is a circuit that is combined with the neutral position switch (and a diode).
it didn't help that the wiring diagram i had was incorrect, gotta love the chinese attention to detail (NOT!).

anyway, i will tell you the real problem but i dont want to jinx it so i will leave it a while.

promise i will let you all know.

Thumper · 02-22-2023, 07:11 AM

EFI is nice when works, and when problems can be diagnosed.

I was thinking a bad wire, but the transience of the symptoms makes me think not.

You have checked the things I would suspect... Fuel pump, coil (did you get the right coil finally?).

The fact that spark disappears after start eliminates fuel system issue, I would think.

Can you borrow a known working EFI controller from someone ("computer")?

The behavior sounds like a safety cutoff activating or something. It starts so I would guess pick up coil/sender is OK.

What is the equivalent of a CDI box in an EFI system? Does it still have have one? I'd be looking at that. If it is integrated with (inside) the EFI controller, then maybe that.

thumpa · 02-22-2023, 08:06 AM

hi there! as i said, i found the problem and will post here soon.

nobody with any sense would lend you an ecu in case an electrical fault on the bike damaged it!

i know of nobody within 100 miles of here who owns the same make and model of the bike anyway. and the parts dealer won't do sale or return in case it is fried when tested on the bike (oh, and there is a 2 month minimum delay as they come from china anyway).

an efi bike with an ecu does not have a cdi - it works by reading the trigger pulse from the crank sensor on the stator and fires the coil (which has a 12v postive connection when ignition switched on) by killing the ground and therby firing the coil. the coil is different to a coil for a cdi system and they are not interchangeable.

back soon.

thumpa · 02-23-2023, 01:55 PM

ok, the fault, if you can call it a fault, was more a design feature combined with human error!

the clutch switch issue, although related, was not the actual cause, it didn't help that i had a rubbish wiring diagram (from the makers) that implied it was linked to the ecu and prevented starting if engine in gear, etc. i guess it was from an older model.

further testing on my bike shows it merely cuts the starter relay switch wire from the starter button.

looking online it seems efi bikes have a fall sensor (as in a sensor that kills the engine after so many seconds if it senses the bike has fallen over) which is connected to the ecu, the ecu kills the engine and will not allow a restart unless ignition or kill switch turned off and on.

now, this is the weird thing... my bike has no fall sensor - it is actually incorporated in the ecu!

i searched and searched and could find no mention of such a thing, it didn't help that the mikuni ecu catalogue does not list my bike's ecu serial number.

sorry if i am boring you but all the symptoms indicated it was a wiring issue or a faulty ecu. hours of testing showed no faults.

it was just pure luck i found the cause of the problem, i had been testing every wire in the loom many times and found that when i moved the ecu around, the engine would stop (looking like a wiring fault) then, i left the loom with the ecu fitted lyingh across the bike, started it and it stayed started. again i though 'a faulty wire' but when i moved the ecu on it's side, after 5 seconds, it cut out. depending on the angle it was at, the time until cutout varied, but when vertical, it did not cut out.

ok, the human error bit.... before this 'fault' happened (had not used the bike for months), i checked the air filter and had to move the ecu from its rubber mounting on the air box... WHEN I PUT IT BACK I PUT IT IN UPSIDE DOWN!!!

when it is upside down it does not cut out after a few seconds, it can be up to five minutes, i only assume it is not the greatest of designs and when upside down, however it is supposed to work (mercury switch??) does not work well. maybe they never expect the bike to end up upside down! tipped to its side it takes between 5 and 10 seconds to cut out.

anyway, sorry for the long post but i have been riding the bike for 2 days including bouncing around in a field with no problems.

i just wish i could find some info somewhere about ecu's with built in fall sensors!

thanks everyone for your valid suggestions over the last week or so.

Thumper · 02-24-2023, 01:45 AM

So it WAS a safety cutoff. Wild intuition!

I suppose it would be downright funny if it weren't for all of the time you put into it

But in the end, it shows that your EFI system is robust and working fine. Good to know

thumpa · 02-24-2023, 03:05 AM

i am still laughing and in a way enjoyed the time on it!

if only i could have found supporting info! not sure why they went for such a complicated way of having a fall sensor though, i guess it made it cheaper than a fall sensor and the wiring, these companies like to shave a few pennies off where they can!

interestingly, when i did consider buying a new ecu, there were 2 for my make and model but the one with matvhing numbers to mine was 220 uk pounds whilst the other was 180 uk pounds...

as for the clutch switch, i dont think i have ever tried to start a bike in gear with the clutch in so i would never have known it was faulty!

cheers!

02-14-2023, 12:09 PM	#31
thumpa Join Date: Feb 2023 Posts: 24	Amazingly I have found the problem! hello! having banged my head against the wall for over a week trying to fix this issue, today i found a fault with the CLUTCH LEVER SWITCH! (the switch that stops engine starting if clutch disengaged). it is permanently in a closed circuit, regardless of whether in or out. disconnected it and engine starts and, even better, stays started! i don't know what made me check it - the fact the engine started made me think it could not be that or it would not start at all. still trying to work out why. almost like a capacitor is discharging. anyway thanks to everyone who offered assistance. great forum.
	3

02-14-2023, 01:13 PM	#32
JerryHawk250 Moderator Join Date: Oct 2016 Location: Houma, La. Posts: 11,561	Glad to see you figured it out. That's strange that you had any spark at all. If there were no spark the safety switches would of been the first thing I would of checked. __________________ 2023 Lifan Lycan 250 Chopper 2023 Venom Evader 2022 Lifan KPX250 2020 Kawasaki Vulcan S 2004 Honda ST 1300 2016 Black Hawk 250 (sold) Keihin PE30 carb,125 main,38 slow.Pod filter,ported & decked head 10:1 CR,Direct Ignition Coil,15/40Sprockets,NGK DPR8EIX-9,De-Cat,Dual Oil Cooler,Digital Cluster 2016 Cazador180 XL 2014 Coolster150 JerryHawk250.com My YouTube Channel
	0

02-22-2023, 07:11 AM	#37
Thumper Join Date: Feb 2021 Location: Kansas City Posts: 2,319	EFI is nice when works, and when problems can be diagnosed. I was thinking a bad wire, but the transience of the symptoms makes me think not. You have checked the things I would suspect... Fuel pump, coil (did you get the right coil finally?). The fact that spark disappears after start eliminates fuel system issue, I would think. Can you borrow a known working EFI controller from someone ("computer")? The behavior sounds like a safety cutoff activating or something. It starts so I would guess pick up coil/sender is OK. What is the equivalent of a CDI box in an EFI system? Does it still have have one? I'd be looking at that. If it is integrated with (inside) the EFI controller, then maybe that. __________________ -2022 5 speed Templar X Orange, OEM 51T rear sprocket, 14T front sprocket -NOS 2020 KTM 250SX (2-stroke motocross), less than 10 hours on it Last edited by Thumper; 02-22-2023 at 07:46 AM.
	0

02-24-2023, 01:45 AM	#40
Thumper Join Date: Feb 2021 Location: Kansas City Posts: 2,319	So it WAS a safety cutoff. Wild intuition! I suppose it would be downright funny if it weren't for all of the time you put into it But in the end, it shows that your EFI system is robust and working fine. Good to know __________________ -2022 5 speed Templar X Orange, OEM 51T rear sprocket, 14T front sprocket -NOS 2020 KTM 250SX (2-stroke motocross), less than 10 hours on it
	0

02-14-2023, 01:25 PM	#33
thumpa Join Date: Feb 2023 Posts: 24	it is indeed very strange jerry but it is the fault. weird as weird can be! cheers!
	1

02-14-2023, 10:16 PM	#34
Dustoff42 Join Date: Aug 2022 Posts: 38	Isn’t it annoying when it was such a simple thing? You seem to know the bike well though. Good job figuring it out. I have had those moments where you think out of the box for a millisecond and it solves everything.
	0

02-15-2023, 03:09 AM	#35
thumpa Join Date: Feb 2023 Posts: 24	thanks dustoff! i can safely say i know the bike a lot better after the last week! i know where every damn wire goes and the schematic diagram for the electrics is burned into my retinas! i shall almost miss this forum now. until the next time.
	0

02-22-2023, 06:31 AM	#36
thumpa Join Date: Feb 2023 Posts: 24	hello chinariders! a quick update .... that was not the cause of my problem! the problem started again about half a mile from my house, luckily i was uphill from where i live which is very hilly. the clutch switch issue was a problem but on only in that it meant i could turn over the engine in gear and with clutch in or out (but it was causing an earth issue there is a circuit that is combined with the neutral position switch (and a diode). it didn't help that the wiring diagram i had was incorrect, gotta love the chinese attention to detail (NOT!). anyway, i will tell you the real problem but i dont want to jinx it so i will leave it a while. promise i will let you all know.
	0

02-22-2023, 08:06 AM	#38
thumpa Join Date: Feb 2023 Posts: 24	hi there! as i said, i found the problem and will post here soon. nobody with any sense would lend you an ecu in case an electrical fault on the bike damaged it! i know of nobody within 100 miles of here who owns the same make and model of the bike anyway. and the parts dealer won't do sale or return in case it is fried when tested on the bike (oh, and there is a 2 month minimum delay as they come from china anyway). an efi bike with an ecu does not have a cdi - it works by reading the trigger pulse from the crank sensor on the stator and fires the coil (which has a 12v postive connection when ignition switched on) by killing the ground and therby firing the coil. the coil is different to a coil for a cdi system and they are not interchangeable. back soon.
	0

02-23-2023, 01:55 PM	#39
thumpa Join Date: Feb 2023 Posts: 24	ok, the fault, if you can call it a fault, was more a design feature combined with human error! the clutch switch issue, although related, was not the actual cause, it didn't help that i had a rubbish wiring diagram (from the makers) that implied it was linked to the ecu and prevented starting if engine in gear, etc. i guess it was from an older model. further testing on my bike shows it merely cuts the starter relay switch wire from the starter button. looking online it seems efi bikes have a fall sensor (as in a sensor that kills the engine after so many seconds if it senses the bike has fallen over) which is connected to the ecu, the ecu kills the engine and will not allow a restart unless ignition or kill switch turned off and on. now, this is the weird thing... my bike has no fall sensor - it is actually incorporated in the ecu! i searched and searched and could find no mention of such a thing, it didn't help that the mikuni ecu catalogue does not list my bike's ecu serial number. sorry if i am boring you but all the symptoms indicated it was a wiring issue or a faulty ecu. hours of testing showed no faults. it was just pure luck i found the cause of the problem, i had been testing every wire in the loom many times and found that when i moved the ecu around, the engine would stop (looking like a wiring fault) then, i left the loom with the ecu fitted lyingh across the bike, started it and it stayed started. again i though 'a faulty wire' but when i moved the ecu on it's side, after 5 seconds, it cut out. depending on the angle it was at, the time until cutout varied, but when vertical, it did not cut out. ok, the human error bit.... before this 'fault' happened (had not used the bike for months), i checked the air filter and had to move the ecu from its rubber mounting on the air box... WHEN I PUT IT BACK I PUT IT IN UPSIDE DOWN!!! when it is upside down it does not cut out after a few seconds, it can be up to five minutes, i only assume it is not the greatest of designs and when upside down, however it is supposed to work (mercury switch??) does not work well. maybe they never expect the bike to end up upside down! tipped to its side it takes between 5 and 10 seconds to cut out. anyway, sorry for the long post but i have been riding the bike for 2 days including bouncing around in a field with no problems. i just wish i could find some info somewhere about ecu's with built in fall sensors! thanks everyone for your valid suggestions over the last week or so.
	5

02-24-2023, 03:05 AM	#41
thumpa Join Date: Feb 2023 Posts: 24	i am still laughing and in a way enjoyed the time on it! if only i could have found supporting info! not sure why they went for such a complicated way of having a fall sensor though, i guess it made it cheaper than a fall sensor and the wiring, these companies like to shave a few pennies off where they can! interestingly, when i did consider buying a new ecu, there were 2 for my make and model but the one with matvhing numbers to mine was 220 uk pounds whilst the other was 180 uk pounds... as for the clutch switch, i dont think i have ever tried to start a bike in gear with the clutch in so i would never have known it was faulty! cheers!
	0