KrZy8 hard starting, intermittent missing

dcarver · Oct 23, 2015

Hard starting, runs much better when warm but not right.

Gas mileage dropped. Idle adjusted up to keep in band.

Compression test across all 4 good.

Dribbling a little gas into the vacuum port and she smooths out.

Replaced #2 fuel injector, no happiness, same symptom.

Any ideas, oh great and wise fourmites?

Thanks in Advance,

KrZy8's Pappy

PhilJet09 · Oct 23, 2015

Questionable plug wire?

Cibrd0wn · Oct 23, 2015

It's time to put her to rest and go pick up the shiny 13 before Don tips her over in the garage.

RossKean · Oct 23, 2015

If its not the injector, I would say plug wire or plug. The same coil fires two cylinders so you would be having issues with more than just #2. Of course, the wires are permanently molded into the coils (I think) so you would be trying a new coil and two wires. Good luck.

Fred W · Oct 23, 2015

Maybe the injector signal is bad coming from the ECU? Try running the test in the Diags.

If it was an ignition problem of any kind it would not smooth out by drizzling fuel into the vacuum port

juniorfjr · Oct 23, 2015

Fred W said:
Maybe the injector signal is bad coming from the ECU? Try running the test in the Diags.
If it was an ignition problem of any kind it would not smooth out by drizzling fuel into the vacuum port

That's how I see it, drizzling fuel would not make a diff if it were ignition.

mcatrophy · Oct 23, 2015

You could probably check for coil/plug-wire by swapping the coils over, even if temporarily (I don't know about wire lengths on the two sides).

ionbeam · Oct 23, 2015

mcatrophy said:
You could probably check for coil/plug-wire by swapping the coils over, even if temporarily (I don't know about wire lengths on the two sides).

Since it's a waste spark system, wouldn't a wire/plug problem with #2 cause a problem with #3 too?

dcarver · Oct 23, 2015

Thank you for good ideas and suggestions.

Unfortunately, or Fortunately, depending on view point, I'm not the tech on this job..

The TPS reads in range and smooth through out range.

I let the tech know that for 1300 gen 2 flavor have a very good DIAG mode.. and suggested sparking the sparking plugs and firing the injectors.

Tech, named Ivan, stated he has a spark tester and the coil is good.. but can't tell what it's doing while down in the hole e.g. possibly shunting to ground.

I suggested a possible vacuum leak on #2?....

He will try spraying tomorrow to see..

..and then click, aha, I wonder.. I think my CC vacuum reservoir ties into #2. Wonder if the reservoir is leaky?

A question... if the fuel injector is removed, and in the DIAG mode, is it possible to make the injector pop and visually see a fuel spray distribution pattern?

Sure wish I had more time to TS this myself.. but I don't. Nuclear jail.

Once again, Thank you for all the help.

OH, regarding the 2013... jeesh, it's looking like late Nov to get it picked up. Maybe SkooterG can ride it to the Hondarosa and leave SkooterBooooogers everywhere?

kaitsdad · Oct 24, 2015

~~Don, try swapping #1 and #2 injectors. If it's the injector, trouble will move with it. If it doesn't,~~ take a look at the wiring harness for #2.

Ok. I just noticed that you already changed the injector. So - (and you've probably already done this) take a close look at the wiring.

wfooshee · Oct 24, 2015

Spraying fuel outside the motor is a Way Bad Idea. Maybe spraying into a sealed container.....

yamafitter · Oct 24, 2015

If you did tie into #2 for the cruise control just pull the vac line and cap it and see if that cures the problem. Then you will know if that is the issue or to look elsewhere.

When in diagnostic mode d37 will fire injector #2 five times as a test. You will hear five definite clicks as the injector coil energizes and then drops out. That will let you know that the ecu, wiring and injector coil is not the issue. No five clicks = problem.

Because of the design of the fuel rail the injector needs to be installed for there to be fuel delivered to the injector so you will not be able to check the spray pattern. You do not need to pull the injector to run the diagnostic test on the injector so there is nothing to be gained by pulling the injector at this point.

By changing the injector you have already eliminated the possibility of a blocked injector anyways.

Good luck.

mcatrophy · Oct 24, 2015

ionbeam said:
mcatrophy said:

You could probably check for coil/plug-wire by swapping the coils over, even if temporarily (I don't know about wire lengths on the two sides).

Click to expand...

Since it's a waste spark system, wouldn't a wire/plug problem with #2 cause a problem with #3 too?

Not if it's the plug lead or some sort of leak to ground near the #2 lead exit from the coil.

TownsendsFJR1300 · Oct 24, 2015

Is it possible the CCT let the cam chain jump a tooth? It'll still run, but crappy..

Aim a lazer temp gun at the header (close to the head) once warmed up and see what cylinder isn't running 100% (if one is out of line). If the temps are all pretty close, it'd point towards the CCT, chain jump.

Different temps (a colder exhaust) will lead you to the "bad" cylinder- as noted, bad spark plug, gap too wide (worn out)

A simple inductive, automotive timing light slipped over each spark plug wire while running should also eliminate any potential issues at least from the ignition coils to the plugs(doesn't rule the spark plug out)

A leak down test is MUCH MORE accurate at getting to the OVERALL health of the engine and simplify narrowing down the issue if its a hard mechanical part failure..

RaYzerman19 · Oct 24, 2015

It is possible to get a weak spark from a spark plug wire, but I believe they are indeed wire, so likely not the wire itself. Unscrew the spark plug end from the wire, check condition or trim off to get fresh wire, reinstall.........

Fred W · Oct 24, 2015

yamafitter said:
If you did tie into #2 for the cruise control just pull the vac line and cap it and see if that cures the problem. Then you will know if that is the issue or to look elsewhere. When in diagnostic mode d37 will fire injector #2 five times as a test. You will hear five definite clicks as the injector coil energizes and then drops out. That will let you know that the ecu, wiring and injector coil is not the issue. No five clicks = problem.

+1 - This is what I was trying to say, but was too lazy to look up which diag test number it was.

If it clicks, that means the solenoid is moving (good).

To flow test an injector, you can remove it from the bike, hook up a pressurized supply line to it and actuate the injector with a battery. Look on Youtube, there are lots of folks that have rigged up injector testers and cleaners this way. But since you just installed qa new one, that should not be the problem.

mcatrophy · Oct 24, 2015

RaYzerman19 said:
, so likely not the wire itself. ..

I thought I was the pedantic one

. The insulation can break down and allow the electricity to leak to frame, often through a crack in the insulation, then tracking along the outside of the insulation until it finds the frame. Only cure is to replace the coil and its wires, since they're moulded in.

rbentnail · Oct 24, 2015

TownsendsFJR1300 said:
Is it possible the CCT let the cam chain jump a tooth? It'll still run, but crappy..
Aim a lazer temp gun at the header (close to the head) once warmed up and see what cylinder isn't running 100% (if one is out of line). If the temps are all pretty close, it'd point towards the CCT, chain jump.

My first thought, too. "Hard starting....Idle adjusted up..." sounds just like it.

TownsendsFJR1300 · Oct 24, 2015

Just curious, how'd you come to the conclusion that #2 cylinder is even the issue?

Another thread maybe?

KrZy8 hard starting, intermittent missing

Help Support Yamaha FJR Motorcycle Forum:

Well-known member

Nondescript FJR Hierarchy Displayed

Well-known member

Well-known member

1 Wheel Drive

Well-known member

Privileged to ride a 2018 FJR1300AS

2 FUN

Well-known member

I'm confused - Just ask my Wife.

O, Woe is me!!

Reigning NERDS Granite Lane Gold Medalist

Privileged to ride a 2018 FJR1300AS

Well-known member

Go Wings&#33;

1 Wheel Drive

Privileged to ride a 2018 FJR1300AS

Economic Plankton

Well-known member

Similar threads

Join the conversation!

Join today and get all the highlights of this community direct to your inbox. It's FREE!

Go Wings!