Fuel Injector sticking

[joebiodiesel]

I guess I should check these things myself before I open my big mouth!

A while back a guy posted that he wanted to install a computer on his FJR that gave him Sequestial Fuel Injection. He got lambasted, and banished to the NPERT quickly. Because nobody there happened to mention that the FJR was already SFI I assumed that it wasn't. I may be incorrect.

In automotive EFI Systems many manufacturers split the fuel charge into 2 parts. They gang fire the injectors at TDC every time. For most cylinders that means the fuel charge is being delivered on the back side of a closed valve. It doesn't disappear, or get wasted. It gets delivered into the cylinder when the intake valve opens. I can also tell you for certain that GM vehicles that are SFI switch to gang firing of the injectors on accleration enrichment and full throttle. I'm sure other vehicles do it as well, but I haven't scoped the injectors of every kind of vehicle out there.

I will throw my 4 channel scope on the FJR when I get home this weekend and see for certain how ours works.

Regardless, swapping the injector wires so the fuel is delivered out of time should make absolutely no difference when used for testing purposes here. If an engine with port injection runs fine, there is no reason an SFI motor running post injection on 2 cylinders won't also run fine. It's not a diesel, so as long as the fuel gets sucked into the cylinder in the correct ratio, it should fire that cylinder, no?

Joe

 

[rushes]

I noticed the FJR was running rough and wouldn't idle properly ever since taking the bike out of storage. I put the bike away in mid October thinking I was going to get in a few more rides last season and with the extended winter, we just had time for a few short rides this season so far.

I pulled the air filter and the K&N was barely showing any dirt so I reinstalled the filter. The plugs were a little old so I installed new iridium plugs and borrowed RaYzerman's Carbtune to check TBS. The bike was still running rough and would miss from time to time.

I noticed on the Carbtune that it was always #3 cylinder dropping out.

Ray stopped in and I had his well tuned ear give a listen. It was either a fuel delivery or spark issue. Since the plugs were brand new and the way the bike would stumble on idle from time to time Ray & I both suspected a fuel issue.

I have a Power Commander USB III and we thought at first that the Power Commander may be reading the throttle position incorrectly so we did a reset and reprogrammed throttle position. That procedure had no effect on the rough idling. We then pulled the leads from the injectors one at a time. Each time removing the injector lead made the idle worse expect for #3 injector which had no effect on the idle. We found the problem.

Now for the solution. I went online to check parts availability and pricing. Online the parts are roughly $125 for injector, gasket & o-ring. My local dealer in Canada listed the injector for $195 and the injector is on back-order. My dealer then suggested that I take the injector over to a local diesel shop that has specialized equipment for testing and cleaning injectors. I gave the shop a call and for $25 they will run a diagnostic on the injector and run it through their injector cleaning jig a couple of times.

If this works out we're golden. I'll know if we have success tomorrow.

And it was running fine before you parked it?

Probably a complicated electrical problem.....

 

[Fred W]

Sorry, I'm a bit late to the party...

Ray stopped in and I had his well tuned ear give a listen. It was either a fuel delivery or spark issue.

Well I could have told you that from way over here, and I can't even hear very well. IOW, a "miss" is always either spark or fuel.

Since the plugs were brand new and the way the bike would stumble on idle from time to time Ray & I both suspected a fuel issue.

My experience has been just the opposite. A single missing cylinder is more often caused by a bad spark condition.

We then pulled the leads from the injectors one at a time. Each time removing the injector lead made the idle worse expect for #3 injector which had no effect on the idle. We found the problem.

Actually, all that test did was prove that it was cylinder #3. By killing the injector to that cylinder the variation stopped because there was nothing to fire. It still could have been the spark that was causing the instabiulity. IOW, you could have pulled the spark plug wire and got the same exact results, and you would still not know if it was spark or the injector.

A while back a guy posted that he wanted to install a computer on his FJR that gave him Sequestial Fuel Injection. He got lambasted, and banished to the NPERT quickly. Because nobody there happened to mention that the FJR was already SFI I assumed that it wasn't. I may be incorrect.

Au contrairre, mon amie! I did point out that the FJR ECU is already a sequential fuel injection system. Right here---> My post

 

[joebiodiesel]

Au contrairre, mon amie! I did point out that the FJR ECU is already a sequential fuel injection system. Right here---> My post

Well...either you went back and edited your post, or I just never read your posts very carefully!

JK, of course.

This makes the second time I missed important info in your posts!!

Joe

 

[yamafitter]

OK things are now much better. Did some other checks just to be sure. I first used the diagnostic feature d36 - d39 to test fire the injectors and all injectors clicked 5 times.

This was somewhat unexpected so I pulled the plugs and checked spark and found spark was good to all 4 cylinders. We then checked compression since I have a compression guage and compression was good and fairly equal among all 4 cylinders.

After having the injector cleaned I noted the bike did not stumble as bad on idle as before.

Ray mentioned when he was here that I should check the mixture screw on #3 throttle body to make sure it was set to roughly 3/4 turn out. I found it was only a 1/4 turn out and reset it and then performed a careful TBS. The idle came up and is now smoother and I have control of the idle speed with the adjustment screw which I did not have before.

It rained all day so at the next opportunity I going to road test but I'm confident all is now good.

I may had completed this sooner but I took some time out from my bike to change Shakin's (Ian) rear tire since he came over with the tire and the BEER.

It was a 2 beer job. One beer to change the tire and another beer to balance the tire.

 

[yamafitter]

Sorry, I'm a bit late to the party...

... IOW, you could have pulled the spark plug wire and got the same exact results, and you would still not know if it was spark or the injector.

I would not recommend doing this while the motor is running.

It would be a shocking experience :dead:

When we pulled the injector lead for #3 cylinder initially it had no effect on idle. If it were a spark issue I would have expected to see a fouled plug when I installed the new ones but all the plugs look good and had the same colour to the insulators.

 

[Fred W]

Sorry, I'm a bit late to the party...

... IOW, you could have pulled the spark plug wire and got the same exact results, and you would still not know if it was spark or the injector.

I would not recommend doing this while the motor is running.

It would be a shocking experience :dead:

When we pulled the injector lead for #3 cylinder initially it had no effect on idle. If it were a spark issue I would have expected to see a fouled plug when I installed the new ones but all the plugs look good and had the same colour to the insulators.

Actually, I have done this before on other engines with no problem, and lived to tell about it! But, you could not REALLY pull the spark plug wire off of one plug of an FJR and expect the same results anyway, because the FJR employs a wasted spark ignition system. Pulling one plug wire would incapacitate two cylinders, which would probably cause the bike to stall out altogether.

And of course the throttle body air screws are not actually "mixture" screws, but I think we all knew what you meant.

Seems to me that the TBS should have been off pretty severely, no? In retrospect we probably should have guessed that the injectors were not the root cause since the symptom was only at idle and cleared up above 2000 rpm. I'd think that sticky or clogged injectors should be as bad or worse at higher flow situations.

In any case, glad that you got it sorted out.

This makes the second time I missed important info in your posts!!

Important? Dunno about that.

It was easy to miss as at that point the thread had pretty well degraded to being nonsensical.

 

[yamafitter]

Sorry, I'm a bit late to the party...

... IOW, you could have pulled the spark plug wire and got the same exact results, and you would still not know if it was spark or the injector.

I would not recommend doing this while the motor is running.

It would be a shocking experience :dead:

Actually, I have done this before on other engines with no problem, and lived to tell about it! But, you could not REALLY pull the spark plug wire off of one plug of an FJR and expect the same results anyway, because the FJR employs a wasted spark ignition system. Pulling one plug wire would incapacitate two cylinders, which would probably cause the bike to stall out altogether.

Seems to me that the TBS should have been off pretty severely, no? In retrospect we probably should have guessed that the injectors were not the root cause since the symptom was only at idle and cleared up above 2000 rpm. I'd think that sticky or clogged injectors should be as bad or worse at higher flow situations.

In any case, glad that you got it sorted out.

I once tried pulling the spark plug lead off my Bultaco Madador SD when the throttle stuck open with my bare hand and I learned from that experience never to try that again. If you need to pull the plug wire while the motor is running I can only recommend the use of insulated tools and keep your hands off the plug lead.

Interestingly, the TBS didn't look that bad initially before adjusting the air screw on #3 throttle body. It was significantly worse after the air screw on #3 was properly set.

 

[BkrK12]

It's easy for those bleed screws to get messed up if you're "chasing" a certain vacuum number. I usually gently seat them all and open them all up about 1 1/4 turns before starting a TBS. Then, try to leave Number 3 alone. I never have any difficulty getting at least 240mm. Trying to get to 250 is what causes you to turn them down too far. That's when you get to the place where your idle adjustment screw doesn't work any more.

You can also open them up too far and then you can't turn the idle down far enough.

Dan

 

[RaYzerman19]

This all started out like it was a vacuum problem..... The normal manufacturing process would set the butterflies with a hard gauge and the screws would be set to a nominal, and I doubt any fine tuning is done until your first TBS. But, I am also leery these screws just vibrate out of place.

I am also confused a bit by the FSM, which does not detail any throttle body settings unless I missed it somewhere. There is reference to the air screws.... "If the air screw was removed, turn the screw 3/4 in and be sure to syncronize the throttle body". How do you interpret that? Normally, an air screw is set by first seating it (gently) and backing it out a certain amount of turns...... So, I agree with Dan's method, but how did you arrive at 1-1/4 turns?

 

[BkrK12]

This all started out like it was a vacuum problem..... The normal manufacturing process would set the butterflies with a hard gauge and the screws would be set to a nominal, and I doubt any fine tuning is done until your first TBS. But, I am also leery these screws just vibrate out of place.

I am also confused a bit by the FSM, which does not detail any throttle body settings unless I missed it somewhere. There is reference to the air screws.... "If the air screw was removed, turn the screw 3/4 in and be sure to syncronize the throttle body". How do you interpret that? Normally, an air screw is set by first seating it (gently) and backing it out a certain amount of turns...... So, I agree with Dan's method, but how did you arrive at 1-1/4 turns?

Trial and error. I think I started at 3/4 turn and worked my way out. I was looking for a setting which put me in the right vacuum ballpark and gave me a good deal of idle adjustment, up and down.

Dan

 

[Fred W]

I am also confused a bit by the FSM, which does not detail any throttle body settings unless I missed it somewhere.

No, even the FSM doesn't detail any method on how to adjust the throttle plate linkage. Which is why I came up with my really, definitely, completely unauthorized TBS procedure last year.

I've done this successfully, as have a few others that have reported back to me on it. I've yet to hear from anyone that said it just didn't work or messed them up.

In my procedure I suggest dialing out 1 full turn CCW on all four screws from lightly seated (after syncing the throttle plates). I'm sure that 1 1/4 turns would work too.

YMMV

 

[RaYzerman19]

Thanks, Dan.

Fred, I read that thar thing a year ago, and got real lucky I didn't have to adjust much of anything. I got away with a normal TBS and she's running saweet now. I did make sure I was 1 turn out as a base line. Thanks for putting that together!

OK, Bill, I know the weather's been crap, but any good news yet?

 

[Constant Mesh]

I might recommend a different air screw setting for the '05 and earlier FJRs. On my '04 I've set the air screws out far enough so they're flush with the edge of the throttle body. All the threads are engaged in the throttle body for good stability and minimal long term screw movement.

I want to have the air screws allowing the maximum amount of air into the system. I know I can adjust them more precisely than the throttle valves. I also know from experience that the air screws can affect engine vibration all the way out to 4K rpm. So their contribution is not insignificant even at typical cruising speeds.

If you open the air screws beyond this point they may not allow for a low enough idle. But I much prefer a borderline fast idle over a slow one so I'm happy with this trade-off.

I have tweaked the throttle valve adjustments but I'm not sure I noticed any significant effect on engine vibration. I think it's possible to do more harm than good if you play with the factory throttle valve settings. Butterfly valves are very crude flow control valves particularly when they're open very much. They function best as a simple on/off blocking valve.

 

[yamafitter]

Thanks, Dan.

Fred, I read that thar thing a year ago, and got real lucky I didn't have to adjust much of anything. I got away with a normal TBS and she's running saweet now. I did make sure I was 1 turn out as a base line. Thanks for putting that together!

OK, Bill, I know the weather's been crap, but any good news yet?

No luck getting out on the bike today and I'm going north to dirt bike for the weekend. I did start the FJR today and let it come up to temperature and the idle is much improved. I have high hopes and will move on to installing the speed bleeders and get the brake fluid flushed. I also need to mount some fresh rubber at the rear and then run up to Wilberforce for lunch to scrub the tire in before heading out to CFR.

 

[RaYzerman19]

In the old service manuals (e.g., CB750 Hondas), it described the best way to set the butterflies. Basically, throttle bodies on a bench, and using a round pin gauge, set all butterflies to the same opening by adjusting the mechanical linkages and screws. This was your rough sync, which you then fine tuned with the air screws once reassembled back on the bike. Fred's procedure gets you pretty much the same thing.

 

[yamafitter]

I been out on the FJR and life is good. The bike is now much smoother both at idle and at pace. Speedbleeders have been installed and all the old brake fluid is now replaced with fresh DOT4. I'll be installing a fresh rear PR2 in the near future and will departing for CFR on or about June 17th.

I'm working out routes for the Garmin since I will shepherding BeemerDon & Seth around while they spend time in the Great White North. I don't think Luddite Don's blow up world globe shows any of the good roads around this neck of the woods.

 

[RaYzerman19]

Good news, Bill!!! If you follow that going east route I gave you, and incorporate Don's diversion to 25 & 93, you'll miss the mountain lookout... still good to carry on 25.... we'll catch the mountain lookout at the NERDS event anyway!! I know you'll figure it out!!

 

[Afast03nNJ]

Have you taken the power commander out to see if that was the cause? Could be an easy fix...

 

[joebiodiesel]

I was fooling around with my bike again last night trying to get rid of my 1-2K miss and I did a quick scope check of the injectors. I figured I'd post the results here to finish the question about SFI on our bikes.

So here it is. Our bikes are definitely sequentially fuel injected. They never revert to port fuel injection like many automotive systems do at full throttle, but they do add asynchronous pulses when the TPS shows the throttle opening rapidly. These are non-timed pulses for adding extra fuel.