FZ1 Charging or Starting Problem

I was wondering if you have any ideas about what could be wrong with my 2007 Yamaha FZ1 motorcycle.

I put in a new battery 2 months ago because with the previous battery, in the morning (after trickle charging all night) it would start up fine, but at night after being at work, it would usually start on the second attempt (switched off then on) when I gave it a handful of throttle.

The new battery made the problem go away for a month, then it started to return.

Last night I swapped in the reliable battery from my back up FZ1. Same thing: perfect in the morning and bad at night.

After charging overnight, the battery voltage is about 13.5 when I disconnect it from the trickle charger. Battery voltage at idle is about 14.2. After I return home and the bike has been sitting, the voltage drops to roughly 12.8.

One thing I noticed just now is that the engine won't even start in the 12.8-13v range. This seems strange because everything I've read says it should start even at 12.6v.

I don't know...maybe since the bike is older, the starter motor needs more wattage.

I thought that the charging system isn't working when I ride the bike and that's why the battery doesn't have enough power to reliably start the engine at night.

It normally rides fine with no flickering dash or lights. One time on the previous battery, it died at idle. But that morning it hadn't been on a trickle charger.

Yesterday, I replaced the regulator rectifier with a tested one I got used. It didn't help.

I was thinking about replacing the rotor part of the stator anyway but maybe I don't need to.

I'm confused because if the battery's voltage goes up to about 14.2 at idle, then the stator should probably be producing enough output and the R/R should be working properly.

I was thinking maybe the O'Reilly's battery was a dud but the current one is a Yuasa that I swapped in from my back up 2008 FZ1. That battery in that other bike had zero issues.

I was thinking parasitic loss, but I only have trickle charger leads attached to the battery. No accessories are connected.

Any suggestions would be much appreciated. Thanks
 
Can you reliably test the input into the R&R I had one leg on my old Honda fail and it would read 14~ on the battery and run off the battery, but wasn't charging during the cycle enough as it was only getting 2/3 the power output from the stator. Not sure if this applies to the FZ as I haven't had it that far apart. So it might be null.
 
I'll test that. But it's strange that the starter won't work properly unless it has 13 or more volts. The battery seems to be charging fine while riding because the voltage with the bike off is 12.8 volts. I don't know...
 
I'm having a very similar problem. Wish I could help, but I'm stumped as well and it sounds like you've done your due diligence. I'll be following this thread; hopefully somebody else has an idea!
 
I tested the charging system and battery and both are perfect. So that rules out the charging system.

I assumed it had a flooded engine so I pulled the spark plugs and ignition coils.

No gasoline smell coming from cylinders. Plugs are totally dry and look great. Coils have perfect resistance.

Air box/intake is not blocked so I think fueling issue.

When I turn the bike on, fuel pump noise sounds good.

I lifted up the tank and the fuel line doesn't look like it was kinked at all.

Any ideas?
 
Can you reliably test the input into the R&R I had one leg on my old Honda fail and it would read 14~ on the battery and run off the battery, but wasn't charging during the cycle enough as it was only getting 2/3 the power output from the stator. Not sure if this applies to the FZ as I haven't had it that far apart. So it might be null.

I think I was confused when I wrote this. I thought I read it as the bike wouldn't crank. But I think that was my mistake.

So after a long time sitting, the bike will crank but not fire. Is this accurate?

It definitely sounds like a lack of fuel.

I would definitely be sure the pump primes. Otherwise you have injectors. Could be a bad wiring or poor contact joint.
 
All good.

Even though I can hear it priming every time, I'm going to hook the fuel pump up to a pressure gauge soon. If it fails then replace.

If it passes pressure test, I'm going to try starter fluid. If it fires for a second and dies then it's likely a fuel starvation issue beyond the pump.
 
Status update: Bike starts now!!!!!!!!

I think the culprit may have been the previous owner's Power Commander V that I've been riding since I bought the bike 6 years ago.

I removed it and besides changing coils and plugs (which were within spec) these were the only changes.

This was the latest update before I tried firing it up again:

-------

I checked one of the spark plugs for spark. It was good. These are new ignition coils and spark plugs. The previous ones were fine, though.

***I finally got time to run a fuel pump pressure test. The primed pressure upon turning the key was 41psi and after a second goes to 39 psi. Pressure drops off after a few minutes to 35psi once I turned the key off.

Again, I have a no start situation. Bike cranks but no ignition.

Previously it would only start fresh off the trickle charger with 13.5v. Wouldn't start with less than 13.2v. Once running it rode excellent.

After it wouldn't start up in my garage no matter the battery voltage, I probably retried 6 or 7 times with no luck. I assumed the engine would be flooded. Nope. Spark plugs were bone dry and no gas smell.

-Fuel line is not kinked
-Air box and filter are good
-Starter motor sounds good
-Coils and plugs are good
-Battery and charging system are good

-------
 
have you checked ALL the wire connections? they can corode even if unseen can hurt the curent flow enought to drop the voltage to prevent things from happening. sometimes a wire can just"go bad".
 
Back
Top