1990 K75 will not run more then 52 miles!

[Al]

Just a quick note. On the MOA site there is an archived piece on how to take the switches apart to clean them. Good pix and instructions. Easy enough to do part from taking the tank off which isn't as formidable as it first seems. All the best beating your gremlins.

[Andy FitzGibbon]

The start switch gets it's power from either the neutral indicator light or the clutch switch. If both of those have connection problems, the start switch will as well.


Andy

[CNRED]

UPDATE
I was in the garage today with a hair dryer trying to get the HES to fail.
I pulled the HES cover, started the bike let it idle on "Choke" until it idled on it's own.  Applied the hair dryer all up until the bike's fan came on.  At that point I felt I was looking in the wrong place. I let the bike sit for about an hour and gave it another shot with the dryer.  Again I kept the dryer on the HES until the cooling fan came on.  I felt I was "barking up thre wrong tree" so I let the bike idle, shut off the dryer and replaced the HES cover.  About 30 seconds later the bike sputtered and quit, would not restart.  Starter turned the motor over, sounded like it wanted to start but was not getting any fuel.  There was no fuel pump run-on after letting go of the starter button.  I pulled the 4-pin connector under the seat, no power at any of the connections with the key on.  Waited an hour, still no power at the 4-pin.
My question is, what interrupts the power to the fuel pump when the motor is hot?

[Laitch]

My question is, what interrupts the power to the fuel pump when the motor is hot?

One reason might be that as aging friction fittings like pin connectors and fuse terminals expand from heat, the mating connections can lose  ufficient effective contact. If they are oxidized that will happen sooner than later. Same can happen with a slightly—almost imperceptibly—loose ground connection.

Pull your fuel pump fuse, clean its spade connections and its receivers with emery cloth–replace it if you've got a spare. Clean your fuel pump plug pins and sockets even if you did that previously and see how tightly together they assemble. Same goes for the ignition switch plug under the tank. Clean your Jetronic main plug and be sure you can hear a click when you reengage it. Plugs should fit tightly and take some effort to separate—not hernia-producing effort though. Grunting shouldn't be needed, but they shouldn't just slip apart easily.

This is all stuff you should do with a used K-bike newly purchased—detail work. If that doesn't change the condition, you're ready to look elsewhere.

[rbm]

++What Laitch said.


There's no safety circuit or cutout that disables power to the engine when warm. If you didn't hear pump run on or measure +12V at the Green/white contact on the pump connector (relative to ground), then your problem is further upstream.  That possibly means connection problems with Fuse 6, possible connection problems with the fuel injection relay, possible problems with connections at Fuse 1, possible problems with connections in the kill switch or possible connection problems with the ICU under the tank near the headset.  Concentrate on cleaning those contacts with Deoxit if you haven't already done so.  Laitch's advice about poor contact at the fuel tank connector is especially relevant since that is a known weak point with the electrics.  It would behove you to replace that connector with a more reliable one at some point.  I would suggest a AMP SuperSeal connector since that has moisture protection built in.  These connectors are very common on Japanese and European cars nowadays and can be bought online or hoarded from the junkyard.

[CNRED]

Laitch and RBM thanks for the advise.
I believe I'm going to have to go conection by connection.
When the bike quit, there was no fuel pump run on, no power at the 4-pin, and no power across the 7.5 amp, fuse #6 with the key on. There was power at the green and white wire in the 4-pin, but only when the starter button is depressed. Power goes away when the button is released.  The brown wire in the 4-pin appears to be providing good ground.
I'm going to check the 4-pin and the #6 fuse in the morning to see if there is power.
I cleaned the 4-pin when I changed the fuel pump but I'll re-visit.  The Jet-Tronic connection is clean, I have two units, I swapped them the last time the bike quit on the road, didn't seem to have any effect.
I'm going to work my way foward from the fuse box and see what develops.
 

[Elipten]

You have and are using Deoxit correct?


Sent from my iPad using Tapatalk Pro

[CNRED]

Elipten
I just bought a can of Deoxit.
I'm going to go back to the connections I have already cleaned and clean them again with the Deoxit just to be sure.

[CNRED]

Just a quick note. On the MOA site there is an archived piece on how to take the switches apart to clean them. Good pix and instructions. Easy enough to do part from taking the tank off which isn't as formidable as it first seems. All the best beating your gremlins.

Al could you send me the link to this MOA piece, I'm sure I will need it.  Thanks

[CNRED]

I've not had a lot of time to source the problem since my last post.
The good part is the #6 fuse is dead on both sides with the key on, as is the fuse holder, I guess that would also be the the bad part. The bike will crank, but obviously with no p[ower to the fuel pump, will not start. 
Maybe it will be easier to find the problem now that I have a problem I can actually see.
Going to pull the tank and fairings today and start checking wiring, connectors, and relays.

[Martin]

At least you have found a starting point, which is a lot better than finding nothing. Keep at it you will be rewarded.  :2thumbup:
Regards Martin.

[rbm]

If you have no power on the input side of Fuse 6 that means you don't have power coming from the Green/Red wire on the FI relay.  Check power on Red to the relay.  If you have power there and no power on either of the Green/Red wires with the ignition turned on, that means a problem with the ICU or ICU connector or that there is no power on Fuse 1 from the Green/Yellow wire. 
- check the power to the FI relay on Red.  Always on 12V, doesn't matter where the key or kill switch are
- Reseat the ICU connector a couple times after cleaning it with Deoxit
- check power from the FI relay on Green/Red (either) with the key on and kill switch in normal.  If none, check the following
- check power at Fuse 1 on Green/Yellow with the key on and kill switch in normal.  If none, then problem is further upstream.


That's enough for now.  Get back with your findings

[CNRED]

ram
   I have power to the red wire with the key off and the key on.  Withn the key on I also have power to the Green/Yellow wire as well, but no power to the two Green and red wires, and obviously still no power to the fuse.  All the rest of the fuses have power with the key on.
I pulled the relay and connected power to the male red prong and power to the green/yellow male prong. I then grounded the male yellow/brown prong.  I then used a test light and found power at the both the green and red male prongs of the relay.
   I'm wondering if the ground to the relay supplied by the yellow/brown wire is good.
   At this point I had to stop, the boss (Wife) wanted to go out to eat.
       To be continued...

[rbm]

You're on the right track. 
1. First test the relay outside of the circuit with a meter to see that it is functional.  Coil should have 50 ohms resistance or so; open circuit means the coil is bad.  Apply +12v across the coil and test for continuity between Pin 30 and each of the Pin 87 - there are two.  If contacts are bad, relay needs to be replaced.
2. If all checks out, then the culprit is now pointing to the start circuitry.  The Green/Yellow to the FI relay comes from the kill switch, which gets its power from the ignition switch.  Test voltage on the Green wire going to the kill switch.  With the kill switch in the normal position, if there is power on Green with the ignition on but none on the Green/yellow, the kill switch is the culprit.
3. If there is no power to the Green wire with the ignition on, the ignition switch is the culprit.

Power to the Yellow/Brown really only comes when the start button is pressed so what you are seeing up to this point is somewhat normal.

Read Bert's page on EFI troubleshooting, especially the section entitled "what happens when you press the start button".

[CNRED]

rbm,
   Ill take a look Sunday when I can get back to it.
Thanks for the info on the Yelow/brown, I believe I would have been chaseing my tail.

[CNRED]

**UPDATE**
Been awhile since I updated this thread.
A little review, 1990 K75rt would quit after 45 to 50 miles would not restart until it completely cooled down, got to ride in the trailer on a couple of occasions.
I replaced everything in the fuel tank, (Pump, Pump Damper,Filter and submersible fuel line) still no joy.
rbm checked most all of my electrical connections and helped me change the four pin connector, I thought we had it fixed until the next morning, it would not start.
A few messages back and forth with rbm, and we felt it might be the fuel sender in the fuel tank.  I emptied and pulled the tank and removed the sender. Long story short, ione of the wires that goes through the seal at the bottom of the tank was not holding continuity.  If I clipped my multi-meter to the wire that was supposed to be inside the tank and the clipped the other multi-meter lead to the wire on the out side of the tank would get continuity, if i applied a little pressure to the sollder joint where the wire goes through the seal I would loose continuity.
I ordered a new fuel sender, (very pricey) installed it and the tank on to the bike.  It started and ran.  It's been very hot here on Phoenix, so up until to day I had not had a chance to ride the bike to see if the situation had been resolved.
Today, I hooked up my trailer to the back of my truck put on my helnrt and took off. Rode for about 30 miles turned the bike off to let it "heat soak" for about 15 minutes.  Got back on rode another 30 miles with out incident and without the trailer to get me home. The bike ran excellently.
It might be a bit premature, but I believe the problem has been taken care of.
Thanks to everyone that responed top the thread and for all of the advise.
Special thanks to rbm for taking time from his busy Phoenix schedule to come and help me source this problem.

[John Lang]

I get lost in the maze trying to follow the wiring diagram relating to the fuel level sensor. How does it affect anything other than the low fuel warning light?

[Laitch]

I get lost in the maze trying to follow the wiring diagram relating to the fuel level sensor. How does it affect anything other than the low fuel warning light?

The current that controls the fuel pump comes from its attachment to the sensor. Damage to certain wires coming through the tank from the 4-pin connector will shut down the pump, shut down the sensor or shut down both. This diagram is from a pre-1990 K75 but it shows the connection between the sensor and the pump.

Fuel pump and fuel sensor wires pre-1990 K75.png (112.87 kB . 398x352 - viewed 434 times)

Maybe CNRED will disclose to us the color of the wire—or wires—that were faulty. That might be helpful.

[rbm]

CNRED would have had a faulty connection on Green/White (Pin 15).  He gave the answer when he wrote "...  if i applied a little pressure to the sollder joint where the wire goes through the seal I would loose continuity".  Only the power lead to the pump goes through that connector.  The return lead from the pump is soldered to a tab that is part of the base of the sensor; in other words, the entire sensor body is grounded.

[Laitch]

Thanks for the clarification, Robert.

[John Lang]

Thank you both, Laitch and Robert.