Hi all. Bit of advice please, bike (84 k100) won't start. Rode it to work a few days ago, briefly started it on Sunday,
went to ride to work yesterday, wouldn't start. Took plugs out and cleaned them, plenty of spark when I checked
them. Plenty of fuel getting through. Sounds like it wants to go but just won't, has run very roughly for about 3 seconds then stopped. Have tried a different computer from another K100 similar age , no change. I wonder if it's lost compression? A Triumph I had back in the day did a similar thing, needed a rebuild. Any help would be appreciated. Cheers, Dave.

Dave,

Check the electrical connection front left of the fuel tank, its the electrical connection to the fuel pump and warning lights. There is a 4 pin connector into the fuel tank. You can access it through the front vent holes, up at the top left. Pull it down and look into it, there are 4 male pins visible. You can use a small precision screwdriver and open them out very slightly so that when you push the connector back on it gives a tighter interference fit.

That step one to do before you do anything else.

The engines are unburstable and lost compression while not impossible I would be looking elsewhere.

Try and unplug your fuel filter, need to take the tank lid off but that's no biggie. Get the filter off the in-tank hoses and just blow through it (don't suck), see if it is clear. Maybe some gunge in there get sucked up when pressurised.
Good Luck.

Hi chaps, thanks for your help, I'll check them out and see how we go, cheers, Dave.

Hi all again, Dave here with some more information from the non-starting early k100. Previously I mentioned that I have plenty of spark at the plugs, starter turns the motor over no probs, there is plenty of fuel being pumped down to the injectors. Now, the bike has non-standard plug caps and wires fitted by previous owner. The plugs are NGK D8ea. I've read on one of the trouble-shooting pages that replacing the original wires and caps can be dodgy especially without using resister type plugs.
Major question is, will replacing the wires and caps with originals potentially fix the non-starting problem or will there be more damage down the line that needs to be addressed?
As I said before, there is plenty of big fat spark at all the plugs when I test them by the usual method of taking them out, plugging them back into the caps, grounding them to the head and turning the motor over.
When I try to start the bike it tries to stumble into life but doesn't make it.
I recall, a chap I knew had a k100 about 1988 which then died in the middle of Victoria on the way back from the Clubman rally. It was a victim of the moisture affected computer malfunction that afflicted early k100s. I remember when we were trying to start it, it would fire then die. My problem is similar. Any ideas or suggestions would be appreciated. Dave.

My LT and the RT both only have the D8EA plugs and no issues from it. I haven't ever had plugs with an R in them.

If my memory serves me correctly the fuel pump gets power from 2 sources. At start it gets a signal when you hit the starter so at that point its getting plenty of fuel. Then once running it gets a different signal via the Hall effect sensor which is now needed to keep the engine running.

Check to see if you can hear the pump running, try it with the fuel tank open. As far as I know these signals come to the ECU under the headstock. The unit itself can be fine but you could have a dodgy connection at the plug or in the circuit.

If its spluttering the fuel filter and in tank pipes should be checked as this would seem to point to fuel filter issues.

Hi 92KK, I'll check what you've suggested, I'm also going to try changing the hall sensors
and ignition computer see if that makes a difference. Pump seems to work OK as when I took of the fuel line to the injector rail petrol pumped out nicely into the bucket I had ready, cheers again, Dave.

You need to use D7EA plugs D8EA is just too cold for winter conditions in Oz or anywhere.
You don't know what you have there so best get a digital meter and measure the resistance of the leads and caps.
They could be resistive caps or not and the same with the leads.
If the leads and caps are not matched to the coil then you can have what looks like a big fat spark and when you subject it to 10-1 compression it fails to work.  At atmospheric pressure 10,000 volts will jump 1cm but at 10-1 compression it needs 100,000 volts to jump 1cm so you can see why it may look good and be no good.
Have you been to the portal page and got the trouble shooting guide.

Normally the Hall sensors are more of an issue when hot, not when you try to start up. That's not to say its not the problem but I would check the connections and earths first. There is one under the petrol tank you definitely should check.

Do check out the fuel pump is operating after the engine cuts out. To do this you will have to leave the fuel lines connected.

Hi Rick and 92KK thanks for the advice, I have been to the trouble-shooting page. Will have to wait
 for the weekend before I try some of that, Cheers again, Dave.

Dave,
I recently made two injector pulse checking LED's (one for each tool kit) as per Bert's trouble shooting guide. Simply plugged into an injector socket, it indicates whether a pulse is present.

So, if you have sparks and fuel in the fuel rail, it may be that the injectors are not opening, ie, no pulse.

The connector between the injector loom and the main loom lurks beneath the wiring under the tank and is easily overlooked when DEoxITing all the contacts.



Just another possibility,
Paul.

bigdavergs wrote:Hi 92KK, I'll check what you've suggested, I'm also going to try changing the hall sensors
and ignition computer see if that makes a difference. Pump seems to work OK as when I took of the fuel line to the injector rail petrol pumped out nicely into the bucket I had ready, cheers again, Dave.

  Hi Bigdave !
Sorry to read about your trouble. According to the above 'quote' you tested the fuel-issue by de-connecting the fuel line and that seemed OK.
My question/remark would be: the fuel can flow out of the line, but: does it reach the inlet-port ? I mean: do the injectors work properly or are they clogged ?!
I had exact the same issue on a 87 RS; cleaned the injectors (there are threats around somewhere with the 'how to') and it ran like factory-new again !

Update: take a look over here; it's on the Tube ... 
https://www.youtube.com/watch?v=VFJlTfHyrUk#t=56

Just check the injectors first, would be my advice ! (Get some new O-rings right away; simpel and lowcost to replace...)
Hall-sensor ? Would be my last suspect...

Cheers and good luck !

Jos

Hi Paul and Jos, thanks very much for your advice, most welcome. Regards, Dave.

Mine did something like that a few years back and it turned out to be the fuel pressure regulator. Cheap second hand part: easy to replace..no probs since.

Hi again all, continuing saga of the non-starting k100. Have re-furbished the injectors with new O-rings etc,
cleaned them out using the method on the 'cleaning injectors' thread, all seem fine. Put bike back
together, still no result. It's making a small effort to start, but just won't catch. Tried it with full choke, no luck
left it for about half an hour, tried again, tried to start then massive backfire. No luck since.
Next step will have to be the full check with meter, unless there are some other suggestions?
Many thanks, Dave.

have you pulled a plug to see if its starved or flooded dave ?

sorry if it is noted  earlier and I didn't see it

My money is on the fuel pressure regulator!

Was in a friends workshop last week. He had a K75 in with same symptoms as you. Turned out it was the computer under the seat, the multipin connector was wriggled and it ran. So he cleaned it all up and put it back. Ran perfectly.

thinking similar 92

the feed from the temp sensor ....again ...and at the puter

Hi all, thanks for the suggestions. I've taken all plugs out and checked for spark, plenty there.
Taken the fuel line off the injector rail and turned it over, plenty of fuel being pumped to the injector rail and, as mentioned I've cleaned and spruced up the injectors. Next step I was going to try was Deox-ing everything.
Anyone know where I can buy a can, either online or in Adelaide?
Thanks again everyone for your advice. Let you know how it goes, Dave.

Your checks are telling you everything you have checked is working ok. Try the computer check as your first step. I have met this on 4 Ks so far and its a very easy fix.

I had the same issue with my old '85 k100rs.  For about a week I would try to start it and it would just run really rough for a few seconds and then die.  Finally it just wouldn't start at all.  I was baffled, but it ended up being the hall sensor.  Swapped a new one in and it fired right up.  The old one looked totally fine, but obviously it wasn't.  Worth a shot.  You can find a used one for about 1/4 the price of a new one.  I bought a used one off eBay for around $90 USD.

you might find jaycar   has 1 > the deoxit  (might be in the little bottle form but still effective ) and 2> the effective replacement hall sensors

check here for Adelaide

http://www.bing.com/search?q=jaycar+adelaide+stores&form=MSNSBE&mkt=en-au&PC=MI9P&qs=AS&sk=AS1&pq=jaycar+adelaide&sp=2&sc=7-15

Evening all, further update. Swopped the water temp sender ( the one bolted into the water pump)
with one from another K in the garage. Seemed like it was a little keener to start, and almost did but still won't.
Thanks Charlie, Rabid and 92 kk. Think I'll give the hall senders a go, see how that works.
Thanks again for the suggestions, regards, Dave.

Swap the computer under the seat with the other K.

Did try that when it first refused to start a few weeks ago 92kk, but no go. Thanks for the thought anyway, Dave.

The water temperature sensor being discussed is NOT fitted in the waterpump. The one in the water pump is only for your temperature gauge and has nothing to do with the engine management. That sensor is fitted in a little stub piece fitted behind the radiator, just inside of the throttle bodies.

Further the bike doesn't 'react' on that temperature sensor when starting. The ECU is taking it's temp signal from the sensor in the AMM for starting, until the engine runs and gets over a certain RPM (720-750).

This information is all readily available on the site. Why don't you go through the fault-finding on the portal page? Lots of good info there.

bigdavergs wrote:Did try that when it first refused to start a few weeks ago 92kk, but no go. Thanks for the thought anyway, Dave.

Same with the unit up under the headstock?

Haven't tried that one 92, I'll give it a whirl. Cheers, Dave.

Hi there Floyd, thanks for your suggestions. Things I've tried so far are, cleaned injectors, new O-rings etc on injectors, new plug caps and leads from EME, swopped under seat computer, checked that fuel pump is pumping, checked for spark, swopped over Hall sensors, checked plug that plugs into bottom front of tank. Next will be to check the water temp sensor. Nearly taken the whole bike apart, might be easier to just restore it completely.
Cheers again, Dave.

Hi all, thanks to all who contributed their advice. Finally got the K running again. Last item I checked
was the water temp sensor. Changed it with one from another K in the garage, started straight away.
Interesting aside, my girlfriend went into a Jcar in Adelaide to buy a tin of DeOxit, asked for it and got blank. astounded stares from the two guys behind the counter. Finally one says, "we haven't had anyone ask for that for years". They did have some though.
Thanks again for the advice, Dave.

good news dave

both on the deoxit and the start event

happy riding mate