Author Topic: Spark and fuel but still no start????  (Read 1386 times)

Offline daveson

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Re: Spark and fuel but still no start????
« Reply #25 on: July 24, 2019, 09:40:08 AM »
It's the same output but there are two output pins,  you need both (unless your resistor is stuffed too :giggles :giggles) if your lucky you only need to replace your relay to get power back to your injectors.

Connect pins 85 and 86 to a battery.  Do you have continuity between 30 and both 87 pins?

Just accept Bert's guide,  what have you got at the injector plug while cranking?
  • Victoria, Australia
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Offline TommyT

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Re: Spark and fuel but still no start????
« Reply #26 on: July 24, 2019, 04:05:21 PM »
It's the same output but there are two output pins,  you need both (unless your resistor is stuffed too :giggles :giggles) if your lucky you only need to replace your relay to get power back to your injectors.

I hope that is all it is...

Quote
Connect pins 85 and 86 to a battery.  Do you have continuity between 30 and both 87 pins?
Working on this test...

Quote
Just accept Bert's guide,  what have you got at the injector plug while cranking?.

I get about 10.5 v
  • Olive NY
  • 1990 K75s, 1990 K75RT

Offline TommyT

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Re: Spark and fuel but still no start????
« Reply #27 on: July 24, 2019, 09:06:58 PM »
I further tested the injectors by connecting a small light to the injector plug and I see pulses.

This bike should be running. ???
  • Olive NY
  • 1990 K75s, 1990 K75RT

Offline daveson

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Re: Spark and fuel but still no start????
« Reply #28 on: July 24, 2019, 10:15:52 PM »
Follow Bert's guide accurately, I'm thinking it should be 12 V can't remember, page three or thereabouts. I printed the earlier version which a see a lot, I've seen a newer version but can't find it back.

You havn't tested the relay yet. As a further test,  with the contacts closed,  would both 87 pins power a headlight?

Keep going through Bert's guide and see where it leads you.
  • Victoria, Australia
  • Current;'86 K100RT Past; '97 Yamaha V Star 650 Yamaha V Star

Offline Scott_

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Re: Spark and fuel but still no start????
« Reply #29 on: July 25, 2019, 07:00:18 AM »
I get about 10.5 v

That would be about what I would expect to see with the starter turning the motor at the same time and engine not running.

Like daveson mentioned, keep going with Berts flow chart.

I'm asking the following for clarification, to make sure we didn't miss something.
In your 1st post you mentioned 36psi fuel pressure(which is good), where did you measure this and how. A gauge tapped into the actual line, or just plugged into the end of the hose coming out of the fuel tank.
When was the last time the fuel filter was changed..... A restricted filter can allow static pressure to build to closed injectors but then when they open and relieve the pressure there would not be enough flow to do any good.
A bad fuel pressure regulator can also cause you grief.
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1997 K1100LT 0302488
1995 K1100LT 0302044
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Offline koapono

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Re: Spark and fuel but still no start????
« Reply #30 on: July 25, 2019, 07:51:55 AM »
just asking the obvious as it hasn't been mentioned: do you have enough compression in all cylinders to add the 3rd element required for combustion (spark, fuel and heat)?
  • prince george, VA (25 miles south of richmond)
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Offline TommyT

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Re: Spark and fuel but still no start????
« Reply #31 on: July 25, 2019, 08:05:09 AM »
That would be about what I would expect to see with the starter turning the motor at the same time and engine not running.

Like daveson mentioned, keep going with Berts flow chart.

I'm asking the following for clarification, to make sure we didn't miss something.
In your 1st post you mentioned 36psi fuel pressure(which is good), where did you measure this and how. A gauge tapped into the actual line, or just plugged into the end of the hose coming out of the fuel tank.
When was the last time the fuel filter was changed..... A restricted filter can allow static pressure to build to closed injectors but then when they open and relieve the pressure there would not be enough flow to do any good.
A bad fuel pressure regulator can also cause you grief.
On the voltage level, also my battery was starting to get run down, it might have been below 12v because after a couple more starts the battery needed charging to turn the starter again.

I use a pressure tester hooked up in line with the line going into the injector rail. It took a couple of bumps on the starter to pump the pressure up, but the line and rail was drain of gas while hooking up the tester, so that seemed to be expected.

I changed the filter earlier on in the troubleshooting when I pulled the pump out to look at the screen on the bottom if it. Everthing looked very clean in the tank and the  pump.
  • Olive NY
  • 1990 K75s, 1990 K75RT

Offline TommyT

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Re: Spark and fuel but still no start????
« Reply #32 on: July 25, 2019, 08:18:46 AM »
just asking the obvious as it hasn't been mentioned: do you have enough compression in all cylinders to add the 3rd element required for combustion (spark, fuel and heat)?
I think it is okay, it ran well when it ran. But I know if a K bike sits too long it loses the oil film in the cylinder walls and that can drop the compression enought to cause a no start. There is a Chris Harris you tube video where he squirts a small amount of oil in each cylinder in a bike that would not start and then it starts. But the bike had sat many months on its center stand and mine has only been 2 weeks now. Also a number of people posted that putting the bike on the side stand gets oil back into the cylinders and I did leave the bike over night on the side stand a couple of days ago.
  • Olive NY
  • 1990 K75s, 1990 K75RT

Offline TommyT

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Re: Spark and fuel but still no start????
« Reply #33 on: July 25, 2019, 11:34:58 AM »

Connect pins 85 and 86 to a battery.  Do you have continuity between 30 and both 87 pins?

I made some small jumper wires and connected 85 and 86 to 12v. Tested for continuity between 30 and 87, zip, none....So is this test opening or closing the relay via the 12v on 85 and 86 and that should provide a connection between 30 and 87?

I did try this on another new FI relay I just got and got the same result. ???
  • Olive NY
  • 1990 K75s, 1990 K75RT

Offline Laitch

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Re: Spark and fuel but still no start????
« Reply #34 on: July 25, 2019, 01:18:57 PM »
If each injector has approximately 12.5 volts with the ignition at On, if each injector pulsates negative voltage when the starter button is pressed, if there is ~35psi fuel pressure in the fuel rail then the spark plugs should be wet after the engine has been cranked but hasn't started.

Are they wet?
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Offline Scott_

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Re: Spark and fuel but still no start????
« Reply #35 on: July 25, 2019, 05:42:26 PM »
Almost sounds like it's time to pull the injector rail(with injectors still connected) and hit the starter switch and see what the spray pattern is... or isn't.
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1997 K1100LT 0302488
1995 K1100LT 0302044
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Offline TommyT

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Re: Spark and fuel but still no start????
« Reply #36 on: July 25, 2019, 06:47:15 PM »
The plugs got wet! After testing the FI reply and cleaning the frame grounds, ECU plug and the box side contacts, and once my friend's test light showed the injector plug getting pluses Idecided put the gas tank on the bike this afternoon and see if it would start. After the fuel pressure built up the bike fired up! I am  not sure  if it was a bad ground or a poor connection with the  ECU, but it is great to get the bike back.

Thank you all for your suggestions and encouragement in helping to troubleshoot this no start problem. I have learned a lot.

  • Olive NY
  • 1990 K75s, 1990 K75RT

Offline Laitch

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Re: Spark and fuel but still no start????
« Reply #37 on: July 25, 2019, 06:52:31 PM »
Idecided put the gas tank on the bike this afternoon and see if it would start.
No doubt about it. Having a fuel tank with some fuel in it mounted on the moto and connected to the fuel system is a big help in the starting process. :giggles
  • Along the Ridley in Vermont.
  • 1995 K75 72,000 miles
I wept because I had no radials until I met a man who had no splines.
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Offline johnny

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Re: Spark and fuel but still no start????
« Reply #38 on: July 25, 2019, 09:55:44 PM »
greetings...

this is what im thinking... put fuel in the tank and it will start...

try that and report back here...


* nostartnofuel.png (164.34 kB . 737x457 - viewed 66 times)

j o
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Offline Scott_

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Re: Spark and fuel but still no start????
« Reply #39 on: July 26, 2019, 07:01:09 AM »
I made some small jumper wires and connected 85 and 86 to 12v. Tested for continuity between 30 and 87, zip, none....So is this test opening or closing the relay via the 12v on 85 and 86 and that should provide a connection between 30 and 87?

I did try this on another new FI relay I just got and got the same result. ???

I see you got it running,, congrats...

About your question, putting +12v(battery + ) on 86 and ground(battery - ) on 85 should cause the relay to close and give you continuity between 30 and the 87/87b terminals.  You should be able to hear the relay make an audible 'click' when you energize it.

I haven't tried it myself in a number of years, but I believe that these relay coils are polarity sensitive(a lot of DC coils are, but not all), and if you connect it backwards, it won't work.
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1997 K1100LT 0302488
1995 K1100LT 0302044
Garmin StreetPilot 2820
Garmin Zumo 550
"One who does not ask questions is ashamed to learn" Danish proverb

Offline TommyT

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Re: Spark and fuel but still no start????
« Reply #40 on: July 26, 2019, 04:00:18 PM »
I see you got it running,, congrats...

About your question, putting +12v(battery + ) on 86 and ground(battery - ) on 85 should cause the relay to close and give you continuity between 30 and the 87/87b terminals.  You should be able to hear the relay make an audible 'click' when you energize it.

I haven't tried it myself in a number of years, but I believe that these relay coils are polarity sensitive(a lot of DC coils are, but not all), and if you connect it backwards, it won't work.

Thanks Scott for all of your help.

Relay, good to know. I got a spare FI relay I will try that, I did not think about reversing the current flow.

Next thing to do, get the fan working....
  • Olive NY
  • 1990 K75s, 1990 K75RT

Offline daveson

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Re: Spark and fuel but still no start????
« Reply #41 on: July 26, 2019, 06:21:10 PM »
I could be wrong but I get the feeling you don't have a workshop manual to help you through it. The wiring diagrams are a big help especially in colour. One of the Haynes manuals has it in colour, Bert also made colour diagrams. Be careful with Haynes, I'm finding more and more mistakes in it.

..."how does a ground have output? " here's a way to think about it. When you put a battery in your brick you connect positive, then you connect negative and you then have a circuit. It was positive until it touched the negative post. When the computer decides the time is right, it accepts negative from pin 85 of the fuel injection relay so power goes from 30 to 87.

Your getting into the inner intimate parts of your brick now,  the more intimate you get,  the more you'll love it.
  • Victoria, Australia
  • Current;'86 K100RT Past; '97 Yamaha V Star 650 Yamaha V Star
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Online Martin

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Re: Spark and fuel but still no start????
« Reply #42 on: July 26, 2019, 06:41:29 PM »
I got the local Office Works to photocopy and laminate my wiring diagram. I wanted them to blow it up as well but they wouldn't do it for some strange reason. If you buy a few Chinagraphic AKA China Graph or grease pencils in different colours they can be used to mark out circuits on the laminate but can be erased when no longer needed.
Regards Martin.
  • North Lakes Queensland Australia
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