intermittent power loss & wd40 death

[kaleb]

1993 K75, 77k miles, Bristol, UK,


Hello folks,


A month ago, half way into a 20mile ride home I lost power above 4000rpm. The bike would go fine until I throttled above that, and if I did she'd do that awful jerking and stall unless I backed off. If I shut off the ignition and started again the problem would go away, until it came back on the next acceleration.


Over the last weeks the problem has gotten worse until she won't go over 2000 most of the time.


I've had a similar problem a year ago, although not as severe, and it was solved by changing the air filter and spark plugs (http://www.motobrick.com/index.php/topic,7845.msg57354.html#msg57354)


I suspect:


fouled electrical connections or grounds
blocked injectors
water in the tank
perished rubber on the crankcrase breather hose and the little vacuum vent caps around the injectors
blocked fuel filter


I've ordered a new fuel filter, replacements for the perished rubbers and some techtron PEA additve.

This evening I started taking things off to clean the electrical contacts, inspect around and see what I could find.

I cleaned the wire connections beneath the coils. I cleaned the earth from the battery.

I disconnected the injection computer and did something I immediately regretted - sprayed some WD40 onto the computer pins.

Now when I press the start button the starter motor turns, the fuel pump pumps, but the bike doesn't start.

I've reconnected the computer plug several times, aware that it might not be seating correctly. But still nothing.

Might I have killed it with a little WD?

Kaleb.

[alexis291]

Have you changed the spark plugs again? If so, what did they look like?


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[kaleb]

Not yet, Alexis. I was thinking there might be some clues in there. I'll have the parts by the weekend and will pull those and the fuel filter etc. But until I solve the new fail-to-start problem I won't be able to tell what effect anything's having (assuming I caused it tinkering with the computer).

[Laitch]

But until I solve the new fail-to-start problem I won't be able to tell what effect anything's having (assuming I caused it tinkering with the computer).

Clean the plug with DeoxIT, preferably, or CRC electronics cleaner. You sprayed a light lubricant on it which wasn't a good strategy and now you need to blast it clean and let it dry. Leave the battery ground disconnected until you finish cleaning it and all the other grounds and electrical plugs.

Your ignition problem might be coincidental but you should clean that plug with the proper stuff.

[kaleb]

Thanks for the help, Laitch.


I'll update in due course.


K

[Laitch]

I'll update in due course.

Check your battery voltage and alternator output, too, kaleb.

[kaleb]

Have you changed the spark plugs again? If so, what did they look like?


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Alexis,


The spark plugs were filthy black. I've replaced them.


I'll get a volt metre for those tests on the weekend, thanks Laitch.


Meanwhile, I've replaced the crankcase breather hose which was really knackered, and the little rubber caps on the 1st and 2nd throttle bodies (likewise).


While the tank is off, and the airbox removed, is there anything else I ought to do in there other than clean all of the electrical contacts and grounds?


Thanks y'all


K

[Laitch]

Shake the debris from your year-old air filter. Be sure your tank vent and fuel cap water drain hoses or ports are clear. Renew your tank insulation if it is tattered. Verify each electrical plug's posts make snug contact with their receiving sockets.

[Laitch]

Be sure your fuel pressure regulator vacuum hose is in good condition and has no trace of fuel in it. A defective coolant temperature sensor can make a bike run rich and hard to start. With the airbox removed, it's a relatively simple task to remove the sensor for testing. The test for it is in the K100 Troubleshooting guide found in the Technical Library card catalog.

[kaleb]

I'm getting 12.37v from the battery.


The fuel pressure regulator vacuum hose is in good condition with no trace of fuel inside.


I've unplugged and cleaned every connection I can find on the whole bike with deoxit. Including the pins to the injection computer. I've just found the coolant temperature sensor but alas have no thermometer so shan't be pulling that this time. I've cleaned its contacts with deoxit.  If I need to go back it will at least be quicker to get to now that I know how to get the air box off!


The tank has evaporated all remnants of fuel (and or water) that were in the bottom,  and I've carefully suctioned out any debris before installing the new air filter. I've put new rubbers in the tap cap and gasket,  and checked the water drainage ports are clear.


While I had it all stripped back I've lubed the final drive splines, changed all the oils,  drained, flushed and refilled the radiator, bled the brakes and finally removed the never functioning abs modules and ordered replacement brake hoses.


Tonight I'll put her back together and get a couple of litres of the best unleaded I can find... prayers to the k gods, keep you posted.


I understand she'll need to be running for me to properly test the alternator output, yes?

[The Mighty Gryphon]

Your battery is crap.

How old is it?

When was the last time it was charged? 

[Laitch]

Your battery is crap.
How old is it?

I'm guessing it is a cheap Varta bought in the summer of 2014. :giggles

[kaleb]

Thanks Laitch! Yeah it was a couple of years old already when I bought the bike that Summer. Never been charged, ahem. And now I look at it,  the cells are all dry, too. Multiple lessons. I shan't bother you all until I've a new battery. Gosh this is an expensive hobby!

[kaleb]

So I've got and installed an Odyssey PC680 battery and, although I can't ride until I've learnt how to reinstall the brakes sans-ABS, this evening she made 95 mph on the stand with no trace of a stutter anywhere through the curve.

Thanks for the input.

Laitch, I would still like to check the alternator output - would that be by testing the battery when switched off, and comparing that to when the bike is running? That's about 12.7 against 13.8.

Kaleb.

[bocutter Ed]

Whats' with the 2pt type?  :dunno  :nono  :hehehe

[Filmcamera]

1.5 actually...  :2thumbup:

[Laitch]

1.5 actually...  :2thumbup:

I see it as usual—10pt—only it's bracketed by html coding. That bug appeared in some of my posts since the NWO here but hasn't been appearing lately.   

[Laitch]

That's about 12.7 against 13.8.

Time to move to the brakes.

[Filmcamera]

Interesting it shows in 1.5 pt to me and I tried four different browsers to see if it was a browser issue but the page looked the same on all of them


I also have not been able to hyperlinks since for a couple of months either


When I post things I often get that size error and have to go in and modify the post after I first post it.

[Laitch]

When I post things I often get that size error and have to go in and modify the post after I first post it.

I had that condition for a while but just kept modifying them. Then it stopped doing that. It's like K-bike repair only without the cost. :giggles

[kaleb]

Sorry about that! I've corrected the format on that, I think.

Cheers, K.

[Al]

So which mtc procedure are you attributing the problem to? Was it the battery? If so I find it strange. I just replaced mine because it wouldn't hold a charge overnight but once started it ran fine. I was sure it was going to be a plugged fuel filter. Or did you change that too?

[kaleb]

Sorry for the delay, Al. I think the initial problem was a fuel starvation type issue. In the past I've solved it by cleaning/replacing the air filter, changing the fuel filter and changing the spark plugs. This time I did all of those things, as well as replacing the fairly leaky crankcase breatherhose and first two throttle vacuum caps.


In terms of the failure to start after that initial maintenance, I think it was that the battery was old and tired and, as it turns out, quite dry. I've replaced it with a maintenance free one.... Still waiting on my new brake lines before I can get her going.


Best
K