Spark and fuel but still no start????

[TommyT]

I need some help figuring out a no start problem with my 1990 K75S, 48 k miles. My bike started to miss at the very end of 100 mile ride in hot weather. During the last 2 miles the bike started to miss, at first slightly and it got worst, I would give it gas and it would start to go and then hiccup, miss, go, hiccup to the point I could not give it much gas under load. I limped it home and turn the bike off and left it til the next day. I tried to start it and there was no life at all, not even a sputter.

I was pretty sure it was fuel problem but I first checked for spark, that's good, also the plug was dry. I then check for fuel and pressure at the injector rail, 36 psi...good. I read that the Halls sensor can go bad when the bike gets hot, so I changed that after I read this:"The I.C.U. is in control of the L.E Jetronic. the fuel injectors are triggered by the Halleffect sensor(s) (Camshaft Position Sensors or Hallsensors) same as the ignition coils. The Fuel Injectors activate after the Hallsensors give there signal to the I.C.U. then to the L.E. Jetronic giving signal to ground the circuit for the Fuel Injectors. " But the new Hall sensor did not change anything. I would guess that injectors are not firing, since the plug was dry and I smell no gas while I try to start it. What should I check next???

[TommyT]

4 pin plug, I cleaned it when I had the tank off..besides does that control the function of the fuel pump? I have 36 psi at the injector rail.

[Laitch]

4 pin plug, I cleaned it when I had the tank off..besides does that control the function of the fuel pump?

Yes. It supplies current to operate it.

 

I would guess that injectors are not firing, since the plug was dry and I smell no gas while I try to start it. What should I check next???

Check the fuel injectors' function. Are you following a troubleshooting guide?

[The Mighty Gryphon]

Loose connector at the Jetronic?  Seems to be lot of that going around lately.

[TommyT]

 Check the fuel injectors' function. Are you following a troubleshooting guide?
[/quote]

Fuel injectors function check....pull a electrical connect and check for voltage jump on a pin in the connector while trying the starter?

No not following a guide, I usually do the check for spark/fuel and then work my down the path of the failure of those. I looked at the top reason list here on MB for no start. Cleaned the 4 pin, did the starter cleaning trick, ignition switch seems good, never had any random electrical problems in the past, up til now it has been solid since I owned it for over 5,000 miles. Is there a more detail guide here on MB I should follow?

[Laitch]

Fuel injectors function check....pull a electrical connect and check for voltage jump on a pin in the connector while trying the starter?

Almost. It should have ~12.5V ignition On, not running, then pulsating negative voltage when cranking. Remove fuel pump fuse to assure the engine won't start.

[TommyT]

Almost. It should have ~12.5V ignition On, not running, then pulsating negative voltage when cranking. Remove fuel pump fuse to assure the engine won't start.

No voltage at either pin. ???

[johnny]

greetings...

poast up some pictures of this no start moto... the only way i can be one with the whack moto is to see it...

i like to find a mostly isolated place... getts into mostly comfortable position. with my jc whitney catalouge of that build date... be at peace... look within... accept all as created... connect with my senses... look at the whack moto... use my mind to connect with the whack moto and be one with the whack moto... then unwhack the moto...

j o

[natalena]

use my mind to connect with the whack moto and be one with the whack moto... then unwhack the moto...

Do you ever find that you can't get a good connection with whack moto due to your inner 4-pin corrosion, or lack of proper grounding in this plain of existence?

At what point does CBP and/or eyeball pizza come in?

[TommyT]

Okay Johnny,

I am at the point of trying anything.....to unwhack the whack.

A picture of the problem child in better times:


Oh, the build date was 9/18/1989.......start unwhacking.....

[Laitch]

No voltage at either pin. ???

Is this response meant to convey that you could not get a static voltage reading with the ignition switch On from any of the injectors, and when you cranked the engine none of the injectors had a pulsating negative voltage? If so, with what were you measuring them and where were you placing the probes?

I am at the point of trying anything.....to unwhack the whack.

I suggest that you continue to be methodical while j o is being paranormal in support.

[TommyT]

Is this response meant to convey that you could not get a static voltage reading with the ignition switch On from any of the injectors, and when you cranked the engine none of the injectors had a pulsating negative voltage? If so, with what were you measuring them and where were you placing the probes?
I suggest that you continue to be methodical while j o is being paranormal in support.

I could not get a static voltage reading with ignition switch on. Figured there was no need to crank the engine to test for a pulsating negative if I had no voltage to start. I only tested one connector, they are very hard to unplug the connector, i picked the injector closest to the battery. It was easiest to get the clip off and that one was still hard to do.

I place my positive probe in the female end of the connector and my negative on a good grounding bolt on the frame that I tested by measuring my battery voltage first to test my ground selection. I tried both wires.

[The Mighty Gryphon]

Loose connector at the Jetronic?  Seems to be lot of that going around lately.

Have you checked it?

[TommyT]

Have you checked it?

Yes I did. I removed it and reseated it. Contacts looked good. Also checked the ICU plug.

[Scott_]

I could not get a static voltage reading with ignition switch on. Figured there was no need to crank the engine to test for a pulsating negative if I had no voltage to start. I only tested one connector, they are very hard to unplug the connector, i picked the injector closest to the battery. It was easiest to get the clip off and that one was still hard to do.

I place my positive probe in the female end of the connector and my negative on a good grounding bolt on the frame that I tested by measuring my battery voltage first to test my ground selection. I tried both wires.

I'm thinking that the engine has to be turning for the ignition ECU to activate both the fuel pump AND the fuel injection relay.(but I could be wrong on that one)

The Green/Red wire is the +12v to the injectors. It comes thru the 'fuel injection relay'(in the electrical box under the fuel tank) and direct from the battery(no fuse). The power to the relay coil comes from the right handle bar kill switch, and before it gets to the kill switch it comes from the ignition switch.... all un-fused direct from the battery.
The relay coil ground is controlled from the ignition ECU, the same controller that activates the spark plugs.

There are at least 4 different plug in harness connections that can be dirty, (ignition switch, rh bar switch, injector bundle, injection relay), the kill switch could be going bad, the relay could be going bad and/or have bad contacts.

Fuse #1 is also fed from the ignition switch/kill switch chain, so it can be a good testing point to check power. If you can measure +12v at fuse 1 with the key on, then you should also be getting the same +12v at the injection relay coil.(it's easier to measure at the fuse).

To check the relay socket:
30 is +12v power in from battery
87 is switched power out to injectors and fuse #6(another good place to test if relay is working)--you will find 2 terminals marked 87.
86 is incoming switched +12v from the ignition/kill switch for the coil
85 is the coil ground output to the ignition control ECU

[TommyT]

So since I have no power to the injectors once I turn the key on need to know what supplies power to them and follow the wiring checking for a break or failed module. Any guess if a relay is involved?

Update, looks like Scott answered, very well, my question while I was typing this. Thank you Scott you have given me  a path to check today.

[TommyT]

Fuse #1 is also fed from the ignition switch/kill switch chain, so it can be a good testing point to check power. If you can measure +12v at fuse 1 with the key on, then you should also be getting the same +12v at the injection relay coil.(it's easier to measure at the fuse).

To check the relay socket:
30 is +12v power in from battery
87 is switched power out to injectors and fuse #6(another good place to test if relay is working)--you will find 2 terminals marked 87.
86 is incoming switched +12v from the ignition/kill switch for the coil
85 is the coil ground output to the ignition control ECU

Results:
Fuse #1 has 12v
Fuse #6 0v
Relay
#30 has 12v
#87 has 0v
#86 has 12v
#85 has 0v

I am not sure what this telling me....since I power at fuse #1 does that say the ignition switch and kill switch are okay? Also since #30 has 12v then power is getting to the relay from the kill switch? 87 is dead which confirms my measuring at the injector plug, but why is it dead? I am not sure what #85 does.

Where is the injector bundle?

Thanks, tom

[Laitch]

I am not sure what #85 does.

Read the list Scott_ gave you.

If your moto's horn works, pull the fuel injection relay, substitute the horn relay for it then check for power.

[TommyT]

Read the list Scott_ gave you.

If your moto's horn works, pull the fuel injection relay, substitute the horn relay for it then check for power.

#85, I guess I should have wrote I don't understand " coil ground output to the ignition control ECU" does/mean.
What is a coil ground output, the term ground output confuses me, how does a ground have output?

My horn does work, where do I check for power, at the fuel injector plug or fuse #6?

[TommyT]

I found the "Bert EFI troubleshooting guide". I should have found this earlier, sorry.

I did notice it said I should for voltage at the injector plug while hitting the starter, not just when the key is on. Is that right or should there be 12v once the key is turn to on?

[Laitch]

I did notice it said I should for voltage at the injector plug while hitting the starter, not just when the key is on. Is that right or should there be 12v once the key is turn to on?

One of the challenging parts of learning diagnosis and treatment is knowing when to believe what you read and who to believe. We all make our own way through that swamp. It's faith-based. I direct you to Reply #5.

[TommyT]

One of the challenging parts of learning diagnosis and treatment is knowing when to believe what you read and who to believe. We all make our own way through that swamp. It's faith-based. I direct you to Reply #5.

Yes I feel like I am in swamp and many distant voices whispering which way out....ha.

If I follow your redirect correctly I think you are saying is to check voltage again at the injector plug with the key on with the horn relay in the FI relay socket.

[Scott_]

TT, if you say that the fuel pump runs, then you should have power to the injectors-- they come from the same relay output.

[Scott_]

Read the list Scott_ gave you.

If your moto's horn works, pull the fuel injection relay, substitute the horn relay for it then check for power.

That won't work, the injection relay has an extra output pin that the horn relay doesn't have....  The horn relay and load shed relay are the same, but different than the injection relay

[TommyT]

TT, if you say that the fuel pump runs, then you should have power to the injectors-- they come from the same relay output.

Yes the pump is working.

Did you have another reply where you asked me if I was measuring relay pins voltage with the relay in? I can't see that post now,  did you take it down?

For some reason since it was very hot the day I rode and I found out that my fan was not working then, but there was no temp warning light, could the temp sensor go/be bad? From the FI troubleshooting guide it says that is part of fuse #6.