1994 K75S cranks, won't start

[RANBUSH]

I rode my 1994 K75S around town in early October this year, and I noticed it died at a couple of stop lights, which is unusual for this bike, but it started right back up and I rode home. I went out to ride it last month and it cranks and cranks, but it won't start.

I did some research on the interweb and saw quite a few posts on this topic; one said, "turn the key on, hit the starter, listen for the fuel pump". I did that this weekend and I swear I didn't hear anything, and I saw no movement of the fuel in the fuel tank.

Tried this again today, and when I hit the starter, I hear the fuel pump, and see fuel moving around. Engine cranks but won't start, fuel pump apparently working, but may be intermittent.

My buddy Greg suggested squirting starting fluid in the air intake for a few seconds - no joy, won't start. He suggested pulling apart the four-pin connector to the fuel tank on the right side of the bike. I swear I saw 12V on three pins with the key on, and then the second time I tried it I saw no power on any of the pins (one of them is ground). Greg suggested putting a timing light on one of the spark plug wires, hit the ignition, and see if the timing light lights up. No joy, no response on the timing light.

Lots of fuel in the tank, checked fuses, all good. Horn and lights, battery charged up, all good.

Lee Fulton pointed me to an excellent troubleshooting flow chart from Bertrand Vogel in the DIY Forum here.

I plan to pull the fuel tank tomorrow and check to see if the Fuel Ignition relay is getting 12V. Any other ideas?

 

[98lee]

Dirty ignition switch contacts
Dirty kill switch contacts
Dirty starter commutator (lots of things get grounded through here)

To name a few.

Take a voltage reading across the battery posts. Take a voltage reading between the hole on the backside of #1 fuse and the negative battery post with key on and the kill switch in the run position. What are the readings?

 

[RANBUSH]

Take a voltage reading between the hole on the backside of #1 fuse and the negative battery post with key on and the kill switch in the run position.
What are the readings?

Thanks for the quick reply, Lee. When you say #1 fuse, do you mean the 7.5 amp FI Relay fuse in the fuse box?

I'll take a look tomorrow, I assume I can get to the backside of the fuse by taking off the right-side body panel, yes?

 

[98lee]

Top fuse.

Remove left side battery cover.
Remove clear fuse cover.
Note that each fuse has two small holes in the back side of the fuse with the amp rating in between.
Use either one of those holes.

 

[pglaves]

Sometimes if the battery is a little bit weak during cranking the voltage is high enough to trigger the injectors but not high enough to cause the ignition module to trigger ignition spark. The result is fuel fouled spark plugs. Thereafter, even with a fully charged battery, every attempt at starting just makes things worse because fuel is added but the fouled spark plugs fail to provide sufficient spark for the engine to start and run.

In my several such experiences over the years step one was to remove and clean or replace the spark plugs. It would be my first next step.

 

[69zeff65]

Don't the bricks have a HES

It's been a while since I chased my tail on a '94 K 1100LT but I seem to remember replacing the HES on it. It eventually turned out to be the four pin connector for the fuel pump / fuel gauge on that one.

 

[pglaves]

It's been a while since I chased my tail on a '94 K 1100LT but I seem to remember replacing the HES on it. It eventually turned out to be the four pin connector for the fuel pump / fuel gauge on that one.

Yes the K75 has an HES. But they seem to be very reliable. In our 650,000 or so K75 miles we have never had an issue in any of several K75s (I still own 4). And in fact I have never heard of an HES failure on a K75 but I am sure there has been one somewhere. Unlike the early Oilheads the K bikes used HES assemblies with appropriate high temperature wiring.

If my earlier suggestion about cleaning spark plugs doesn't cure the problem then I think it is back to basics. Check for squirt and check for spark.

 

[motormike]

I'm no expert, but if you tried starter fluid in the intake and it didn't even fire, that indicates no spark on any cylinder. I'd grab some new plugs and check for spark, and if no spark, backtrack from there.

 

[pglaves]

Looking back at Post#1, the occasional stall and restart could be a symptom of water in the fuel. And water in the fuel has been known to clog fuel filters on K75 bikes. If other approaches don't pan out then dosing the fuel with IsoHeet in the red bottle and changing the fuel filter would be a good next step if fuel delivery to the injectors seems compromised.

 

[Paul_F]

Sometimes if the battery is a little bit weak during cranking the voltage is high enough to trigger the injectors but not high enough to cause the ignition module to trigger ignition spark. The result is fuel fouled spark plugs. Thereafter, even with a fully charged battery, every attempt at starting just makes things worse because fuel is added but the fouled spark plugs fail to provide sufficient spark for the engine to start and run.

In my several such experiences over the years step one was to remove and clean or replace the spark plugs. It would be my first next step.

Paul's advice above saved me a major repair bill for work that a local mechanic wished to do several Septembers ago for the problem that was reported in this thread. I was informed that the sprag clutch needed replacing and the engine needed a rebuild as there was only combustion in only one of the four cylinders. Told him I'd think about it over the winter. Took the bike for a ride with dry spark plugs to discover there was no problem with the K's power. I parked the bike and that winter, someone had the same problem and Paul Glaves posted his advice. I installed a new battery and all became well for the last 20,000 km or so (at a very reasonable price).

 

[RANBUSH]

Sometimes if the battery is a little bit weak ... The result is fuel fouled spark plugs ... It would be my first next step.

Paul - pulled the plugs today, they're a little discolored, but dry. Might be time for a new set, my records says they're seven years old, ~13K miles on them. Gap is 28 on all three plugs.

Lee - I've got 11.84V at the battery, and 11.64V at the #1 fuse. Battery is a four-year-old Motobatt, maybe it's getting tired?

 

[Omega Man]

Might want to check the voltage when trying to start the bike.
OM

 

[RANBUSH]

Might want to check the voltage when trying to start the bike.
OM

Yepper, good call. I'll try that tomorrow. Thanks.

 

[98lee]

Your battery voltage is very low.

You need to maintain good voltage while you are trying to find what is wrong with your bike. Trying to start your bike with too low a voltage can lead to the starting solenoid contacts welding together. You don’t need to add that to your problems.

Try fully charging the battery and check its voltage about 6 hours after it comes off the charger.

 

[RANBUSH]

Try fully charging the battery and check its voltage about 6 hours after it comes off the charger.

Thanks, Lee. I have it on the charger now and I'll check the voltage again tomorrow about 6 hours after it comes off.

 

[98lee]

Around 12.7 volts is fully charged.

 

[RANBUSH]

Around 12.7 volts is fully charged.

The battery was at 12.84V yesterday AM after being on the charger overnight, and it was still at 12.84V a few hours later.

I am away from the bike this weekend, but I will also try checking the voltage when I'm cranking it, as Omega Man suggested, when I get back.

Thanks for all the replies.

 

[98lee]

Ran,


Now that you have a fully charged battery, you can begin trouble shooting. Don’t let the battery run down below 12.2 volts.

Listen for the pump.

Check for spark. Pull plugs and ground them to insure they are all firing properly.

If both seem ok, you might want to pull the injectors while still connected to the fuel rail and verify that they are actually spraying properly. Do this OUTSIDE with a large piece of cardboard between the injectors and the bike. Have a fire extinguisher at the ready. Before you pull the injectors, clean the area around the injectors with compressed air to keep the sand out of the engine.

 

[RANBUSH]

Ran,

Pull plugs and ground them to insure they are all firing properly.

If both seem ok, you might want to pull the injectors while still connected to the fuel rail and verify that they are actually spraying properly.

Thanks, Lee. I heard the pump cycle the other day. I'll try grounding the plugs and checking the injectors next week.

 

[RANBUSH]

So the good news is that the plugs are sparking when I hit the starter, altho the spark is kinda weak, yellow-white in color. And the fuel pump makes noise when I hit the starter, and there's fuel in the line going to the injector rail.

The bad news is when I put a voltmeter on the four-year-old Motobatt, when I hit the starter it is going down to 11V or so when cranking. I am using a cheap Harbor Fright voltmeter, is that accurate enough for a load test on the battery?

Time for a new battery?

Thanks for all the replies.