K75S Died at traffic light, won't start

[KJM00]

Like the subject line suggests. I was riding my k bike on the way home a week back or so, and it came to a slow death at a traffic light.  I haven't been able to get it to start since. I know that there's a lot of electrical oddities that come with the old brick, as such, I ran through the common ones that Jo posted. I'll attach for clarity but I ran through one through five. when engaging the starter the engine is turning over, but it's not catching. I can also absolutely hear my fuel pump whirring, as well as I had my ignition switch rebuilt about a year back from it having catching issues. looking for any suggestions for the next step, one of the big things that I wanted to throw out there though is that I don't smell fuel or feel compression coming from the exhaust.

to add some of the obvious, full fuel tank, couple year old fuel filter, clean tank clean fuel feed to the spark plugs. battery is brand new as well, tried pulling my spark plugs, but I'm not sure that I have a long enough wrench 

[KJM00]

for clarity I ran through all of this

[daveson]

Remove the fuel tank filler assembly so you can check that fuel is returning back to the tank. Also look check that the fuel lines are still connected to the filter, pump etc, and for splits.

[The Mighty Gryphon]

How about some gory details of your bikes death throes?

How far did you ride before the engine died?  Was it sudden, or was it acting up for a while before it died?  Were there any problems with getting to high rpm?  Did it just suddenly stop running?  Or did it lose a struggle with life? 

When you tried to restart it, did you get a gas smell at the exhaust?  Were the spark plugs wet after attempting to start the engine?  Have you tried to start it with a fully charged battery and the tank connector unplugged?  One of the problems with fuel injection is that once you flood the engine, the injectors will just keep pumping more fuel into the cylinders to keep it flooded.  By cranking with the tank unplugged, you will eventually blow all the extra fuel out so the engine has a chance to actually fire.  You can also accomplish this by pulling the #1 fuse.

[Laitch]

. . . fuel feed to the spark plugs. battery is brand new as well, tried pulling my spark plugs, but I'm not sure that I have a long enough wrench 

This phrase is incomprehensible. If you can't—or won't—check the plugs, how do you know they're wet with fuel? In June 2017 the moto had start/running problems. You indicated that you repaired a prong on the fuel injector relay and that cured the problem. Have you tested that relay circuit again?

[KJM00]

interestingly enough it was wet around 2 out of three of my spark plugs which probably shouldn't be the case in normal operation. but that was how I assumed they were wet. however, at the time that I was able to carve out time to look at those, I couldn't locate my spark plug wrench. I'm going to go back and start looking for that to actually pull the plugs as my next step.

as far as the details of the bike are concerned. it was exactly as going to as well as can bee. No historical issues leading up to the point of it stopping running at all. The only thing was that I replaced my vacuum hose (Z-hose) but that wasn't a performance issue. that was me just trying to be kind of the bike and noticing that the prior hose was cracking.

to include more details on the way that it died, it didn't act like it was gasping for air or gasoline, it just slowly faded when it shut down. I had been using it as a daily rider to work for about 2 months putting on a few thousand miles.

[The Mighty Gryphon]

interestingly enough it was wet around 2 out of three of my spark plugs which probably shouldn't be the case in normal operation. but that was how I assumed they were wet. however, at the time that I was able to carve out time to look at those, I couldn't locate my spark plug wrench. I'm going to go back and start looking for that to actually pull the plugs

to include more details on the way that it died, it didn't act like it was gasping for air or gasoline, it just slowly faded when it shut down. I had been using it as a daily rider to work for about 2 months putting on a few thousand miles.

I'm confused.  It was wet around the plugs?  How did you know without removing them?  Was there fuel around them outside of the cylinder?  Are they loose?

That the engine slowly faded into it's final demise tells me that your problem is likely to be related to the fuel system.  That is where I would concentrate my efforts.  Pump delivery, fuel filter, hose connections in the tank, pressure regulator, injectors, temperature sensor, etc. 

[KJM00]

appreciate the insight and thank you folks very much. current efforts are focused on evaluating the spark plugs to make sure fuel was making it to them. finally got my hands on my wrench, I may also replace them because they're incredibly old regardless. thereafter, I'll start digging into the fuel system. The wetness around the spark plugs. I'm hoping it was just a anti-seize residue and not actual fuel making it past them

[KJM00]

My spark plugs ended up being dry after all, I replaced all three of them which was an ordeal in itself. The guy before me used 5/8 champion spark plugs so my wrench didn't fit it and I spent an hour or so trying to make that work, lol. tested the coils as well as spark plugs and all is well but they weren't getting wet and no fuel smell from exhaust. lifted up my tank and replaced all the fuel lines as well. a few of them were pretty well damaged. and I also had to liftk the air box to get to everything. I suspect I'm looking at electrical issue with relay or pump at this point.

[The Mighty Gryphon]

Are you sure the pump is supplying fuel to the rail?

[KJM00]

I'm not for absolutely certain, but I've disconnected my fuel rail twice during troubleshooting and each time it's purged quite a lot of fuel

[The Mighty Gryphon]

Did you run a hose from the outlet of the rail into a jug to see how much fuel is going through the system when the pump is running? 

[KJM00]

I have not, but that sounds like a good next test!

[BearTrap]

I had a similar problem with my 1990 K75. I checked all the usual suspects and all check out fine. Turns out it was a failed Hall Effect Sensor. Replaced the sensor and it started right up. No issues since.
You can bench test the sensor yourself (see attachment).

[frankenduck]

Ignition switch. Maybe fuel tank connector.

[KJM00]

Disconnected the fuel line that feeds directly into the rail and turned the key over. Absolutely zero fuel coming from the line that would feed into the rail. All hoses have been replaced on the tank and are properly sealed. four pin electrical connector was resoldered a few years back because it was problematic at one point
 I believe it's got to either be one of the two fuel pump relays or the fuel pump itself.

[frankenduck]

The motor has to be turning for the fuel pump to run. Turn the key on and then hit the start button to test the fuel pump operation.

[KJM00]

I guess I didn't specify entirely, what I meant was that I disconnected the fuel rail and set it in a jug, stood there and turned the engine over (Key + Pressing Start) for 2 to 3 minutes without a drop of fuel.

[frankenduck]

Next thing I'd try is jumping power to the fuel pump. You can put alligator clips on the  terminals. (The smaller diameter terminal is 12V, the bigger one is ground.)  Connect the wires to the pump before putting power to wires. For obvious reasons you don't want to risk creating sparks in a gas tank. (TWA Flight 800)

That will tell you if the issue is the pump or not.

[The Mighty Gryphon]

Have you tried applying 12 volts directly to the tank connector to see if the pump motor will run?  I would do that before attempting to jump power to the pump in a fume filled tank.  It would tell you if the problem is the pump or the relays and wiring that supplies power to it.

[KJM00]

Kinda a dumbie, but how would you recommend testing 12V directly to pump, exactly? Hook Trickle charger to 4pin connector?

[frankenduck]

Kinda a dumbie, but how would you recommend testing 12V directly to pump, exactly? Hook Trickle charger to 4pin connector?

I'd use the bike's battery. A trickle charger probably doesn't put out sufficient current.

If you're applying power to the connector:
Green/white wire is fuel pump power 12V+
Brown is ground

[KJM00]

I tried direct connection to my fuel connector from my battery to no avail. I suppose the next step is to drain my tank. remove my fuel pump and try to energize it outside the tank

[frankenduck]

I tried direct connection to my fuel connector from my battery to no avail. I suppose the next step is to drain my tank. remove my fuel pump and try to energize it outside the tank

Something else to try before pulling the pump:

Put a voltmeter to the main wiring harness connector for the tank and see if you get 12V when you hit the start button and spin up the motor.

[Laitch]

I believe it's got to either be one of the two fuel pump relays or the fuel pump itself.

The only relay directly involved with the fuel pump is the fuel injection relay. Have you checked Fuse #6? It's the fuel pump's fuse.