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1Back to top Go down    Cutting out because of overheating on Tue Jan 19, 2016 2:52 am

Big G

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I have noted this is a very popular topic and probably over-posted, but here is my experience:

It is the height of summer in sunny South Africa, and with temperatures in the mid to upper 30's (deg C), my K100 RS is cutting out again Evil or Very Mad

I previously had this issue, traced it back to loosely fitting relays (they had all "popped" out somewhat, probably because of bad roads) but once I cleaned the pins and fitted them all the way down, the cutting-out problem all but went away. (I also checked and cleaned up the fuel pump connector.)

Until yesterday, that is. A couple of km's (luckily) away from home - dead. Ignition and dashboard lights fine, but no fuel pump whirr (exact same symptoms as previous). However, where I normally waited for a couple of minutes (10 - 15), and then the bike would start again, after more than half an hour, the fuel pump was still not activating. I fiddled with the relays, unplugged and reconnected the fuel pump connector, tried to cool the relay box done, but eventually got my son to come and give me a tow home.

Lo and behold - while scratching my head in the garage, there she starts again, idles with no problem! This was about an hour and a half after the bike initially died.
😕

I also fitted an Indoor / Outdoor thermometer I had lying around, and out of interest, measured as follows between outdoor Ambient temperature and the temperature inside the relay box (all in deg C):
Ambient  Relay box  Comment
23          51            After 10 min freeway riding +/- 160 km/h - NO CUTOUT
24          51            After 20 min in traffic (stop/go) - NO CUTOUT
22          45            After 10 min freeway riding +/- 160 km/h - NO CUTOUT
32          54            After 10 min freeway riding +/- 160 km/h - NO CUTOUT
34          59            After 20 min in traffic (stop/go) - NO CUTOUT
31          51            After 10 min freeway riding +/- 160 km/h - NO CUTOUT
36          61            After 20 min in traffic (stop/go) - CUTOUT
29          32            After about 90 min standing - Able to restart

A local K-bike expert suggested I buy a new fuel pump, but before going that route, I will do the heat test on the hall sensors and try and re-crimp the fuel connector plug pins. The frustrating thing about this problem though, is you never know when you have solved the issue or not. I have read just about all there is to be read on this forum, but any other tips or tricks will be welcomed  Laughing


__________________________________________________
1990 K100 RS (2015 - Current)
2005 R1150 GS - 35000 km (2007 - 2010)
1980 R80 GS - 28000 km (2005 - 2006)
2000 F650 GS - 102000 km (2000 - 2004)
1984 Suzuki Katana 750 - 72000 km (1984 - 1986)
1982 Suzuki DR500 - 48000 km (1982 - 1984)
    

2Back to top Go down    Re: Cutting out because of overheating on Tue Jan 19, 2016 3:41 am

charlie99

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i wonder could a temperature sensor help out with the diagnosis ,,,they are usually mounted in the water pump region

it may indicate weather you are having an overheat issue in the cooling system

don't forget the temp sensor for the fuel injection controller resides in the output stub from the motor ...and in this location get way hotter than after the cooling of the radiator back to the water pump .

first thoughts are that possibly the thermostat is intermittent operation ...and not fully opening when needed ..( this would super heat the sensor in that water stub with little flow happening ) causing the injection to stop ?

when in this stoped condition you could quickly pull the connector to the underseat ecu and measure pins 13 and 10 with a multi meter ...the measurement should be over 100 ohms, if under , then investigate the water paths thermo stat etc
you may need to understand that there is a bypass flow out of that water stub, behind the radiator (controlled by the thermostat) also ..that is there to present hot water to the thermostat so it start working

 


I have similar issues ..to my way of thinking in and around idle conditions in city traffic at above 35c temps  and have replaced the thermostat with good results

you didnt say weather you have escape of fluids from the water expansion tank  ...radiator cap area etc ? or if you are using glycol (water treatment additive ) which helps keep the water from boiling ...when under pressure ...or if the water level was low or high to the filler cap ? the seals to the filler cap are very important for good and reliable operation .in high temp conditions .  and you didn't specify if the motor stopped by itself and then failed to be able to restart after ...which might indicate the temp sensor issue ,,,or some other event
you didn't say if the fan came on before it stopped also ,,,does it work properly ?


just to add ...when travelling along at speed there is usually a great good cooling effect through the radiator system requiring very little thermostat operation to run nicely ...even if the thermostat is only in partial operation

hope this might be helpful at least


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cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%O
    

Big G

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Tx for the feedback Charlie

To answer your questions:
- No water leaks from coolant system.
- Not sure of Glycol in coolant, seems like a good idea to flush and refill, adding Glycol (will do).
- Water level slightly above "normal" - seems OK.
- Engine cut out (with ignition etc on), but cooling fan was running.
- Switched Kill switch off and back on, and the first time, both fan as well as fuel pump ran. Pressed starter after which both stopped. Many times of switching on after that did not start either fan or fuel pump (but starter was swinging the engine). After about one and a half hours, switched on and fuel pump ran, allowing starting.

Interestingly, the temperature in the relay box was 61 degC when I stopped - this kept climbing to a max of 68 degC while the engine was off before starting to drop. 

Hope this helps you help me!


__________________________________________________
1990 K100 RS (2015 - Current)
2005 R1150 GS - 35000 km (2007 - 2010)
1980 R80 GS - 28000 km (2005 - 2006)
2000 F650 GS - 102000 km (2000 - 2004)
1984 Suzuki Katana 750 - 72000 km (1984 - 1986)
1982 Suzuki DR500 - 48000 km (1982 - 1984)
    

4Back to top Go down    Re: Cutting out because of overheating on Tue Jan 19, 2016 6:34 am

RicK G

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The engine will not stop because of overheating but if you stop it then it wont start till it cools down quite a bit.
Fan comes on at 111°C  light comes on at 113°C and I think it is 116°C which is the point at which it wont start till cooldown bu I am not sure what the temp has to be before restart can occur.
The Hall sensors will cut out when the engine gets to operating temp but that is a sure sign they are failing and usually don't let the bike restart till well and truely cooled.
To be honest I would say that the problem you are having is vapour lock because the fuel in the lines is very hot and possibly the fuel in the tank is boiling.
I had to change the fuel pump by the roadside a few months back but when I tested the old pump it was fine and I think it probably was vapour lock or boiling fuel.
The fuel was low and the engine sounded like it was running out so I quickly pulled into a convenient fuel stop and filled and all was well till it heated up and then started running bad then stopped and wouldnt start.
I had a spare pump in the camper trailer so I put it in but had to wait about an hour for the fuel to cool enough so as to not burn my hand when I put it in the tank. This was a day that was over 40°C and I had a small cooler on my return fuel line attached.


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If everything seems under control then you aint goin fast enough:- Mario Andretti
Bikes 1986 K100RT, 1993 K1100 LT, 1994 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki X 2 & 1976 SR 500 Yamaha for now
    

5Back to top Go down    Re: Cutting out because of overheating on Tue Jan 19, 2016 6:37 am

charlie99

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kinda sounds like an overheat event to me

the temp sensor in the water stub is the one that tells the injection controller to run or not ...that controller operates the fuel injection relay and when it goes to a start condition (by pressing the start button ) it looks at current settings ...and if too hot  (low resistance on pin 13 and pin 10 ) there is dynamic lockout applied to the injection system on a start event .

the reading of the relay box whilst interesting is by no means an indication of the state of the heat in the motor (have measured tank temperatures of over 56 decrees c ) on the outside of the tank ..I would imagine that at the back of the whole motor assembly during really hot days this would not be uncommon . just have to get it from affecting your legs is the key ...as the whole thing sits behind a radiator that should be temperature controlled by the thermostat to around 86 degrees c ...so up from that is almost a prerequisite to a running and properly warmed motor .

if there was a slight leakage of the electrics  by some form of partial short circuit across the temperature sensor circuit (thus lowering the resistance reading artificially - by a parallel circuit to ground )  then it could do as what has happened or the sensor just maybe faulty or there is a bridge of corrosion across the sensor connector itself  ... I have cleaned the connections of that sensor ....and eventually took it out and cleaned up the threads that the sensor uses to make a good ground connection

slightly above normal in the overlow - reservoir tank is not an indication of what the fluid levels inside the radiator

pull the tank back a little undo the radiator filler and check .....quite often there is air in the system ...which could affect the heating effect ....a lot of us know to lean the bike to the left whilst sitting on it to let the air bleed to the filler cap housing ....I find that  small block of wood ...say 20mm thick under the right hand centre stand leg  lets this air bubble escape out of the system so I can refill it to the brim .
dont forget that air expands far more than water during an overheat situation.

this is all I could recommend ...without "hands on" and "pushing things around" exploration with a good multi meter .
I guess there may well be many more observations to come from others  with some more experience

but I found that a faulty seal on my filler cap led to some amazing overflow and heat related events during a few years on the road ...now sorted and learned ..

hope that helps


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%O
    

6Back to top Go down    Intermittant cutting-out : SOLVED!! on Mon May 23, 2016 4:52 am

Big G

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Hi there all, and thanks for your patience and much advice on this issue.

I have been living with the cutting-out on my bike for almost a year now, and tried all sorts of remedies, especially wrt the relays and the temperature inside the relay box.

Unfortunately (and fortunately) the K100 died a couple of weeks ago - unfortunately because I had to get a trailer to tow me home, but fortunately because the cut-out persisted, I could trace the electrical circuits in the comfort of my workshop at home.

I eventually traced the break in the connection to the moulded plug on the fuel sending unit that sits at the bottom of the tank. Four wires (three and ground) go through this plug into the tank, including the positive (+12V) to the fuel pump. This connection was broken inside the plug, probably due to age, vibration and heat.

I think that when this plug got warm (and it does, right above the engine there), it expands a bit, breaking the connection or increasing resistance enough to stop current flowing. In my solution of "cooling down the relays", I would lift the tank, allowing some airflow, the plug cools down, contracts just enough to make the connection again, and off we go, until next time.

I have now installed a new fuel sending unit, and the bike is going, better than ever before (probably getting full voltage on the fuel pump for the first time in a long while!).

My MO was:
1. Check for 12 V on the fuel pump terminals inside the tank. In my case, nil.
2. Connect 12 V and Ground to terminals of fuel pump to check if pump OK - in my case it was. (This is quite a risky operation, as 12 V DC will probably generate sufficient spark to ignite any fuel fumes inside the tank, so BE VERY CAREFUL here.)
3. Using a multimeter, connect the black lead to Ground, and the other (Red) lead to a thin sewing pin. Carefully stab through the insulation of the (in my case green) wire to check where the voltage drops away (0V or <12V). In my case, I found 12 V from the female socket connector, on the other (male) side of the socket connector, all the way up to where the wire penetrates the moulded socket, and nothing (0 V) inside the tank.
Remember that you will only read 12 V for about 3 seconds after turning on the ignition, as the electrical circuit primes the pump and then switches it off again, until the engine is started. This is however sufficient time to see the response on your multimeter before working your connection further up the line and switching on again.

Hope this is of use to somebody out there battling with the same problem!

I attach a pic of the fuel sending unit.
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K100 Fuel sending unit (bolts to bottom of the tank)
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Last edited by Big G on Mon May 23, 2016 4:56 am; edited 1 time in total (Reason for editing : Trying to include picture)


__________________________________________________
1990 K100 RS (2015 - Current)
2005 R1150 GS - 35000 km (2007 - 2010)
1980 R80 GS - 28000 km (2005 - 2006)
2000 F650 GS - 102000 km (2000 - 2004)
1984 Suzuki Katana 750 - 72000 km (1984 - 1986)
1982 Suzuki DR500 - 48000 km (1982 - 1984)
    

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