Stuttering fuel between 2-3000rpm - Wrist Twisters
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post #1 of 19 Old 07-27-2019, 03:08 AM Thread Starter
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Stuttering fuel between 2-3000rpm

The old hornet has developed a problem in the rpm range between 2-3000rpm range. Chugging, not quite spluttering, but jerky fuel delivery and output...this was intermittent. The bike rode fine for a while then the problem returned. It seemed fine above and below the 3-4 range.

Also...yesterday evening I was in a storm and the bike and me were soaked through for close to an hour.

My assumption is that its the PC III....so I changed the maps, to the richest one I have, and the same problem occurred. Have been running the erions I believe or whatever the thing is called, for many months and it has been perfect.

Could the water have damaged something? My naive hope is that once the thing has dried out the problem will vanish.

Problem with the PC III is that I didnt install it! Too many wires, so I am concerned of course that I may need to take the thing to a grease merchant with some auto electric experience, if the problem persists.

Any ideas folks?

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post #2 of 19 Old 07-27-2019, 04:12 PM
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Check for signs the FPR has failed.
Make sure your coil connectors are all good.
To eliminate the power commander as the problem you really need to disconnect it and take the bike back to stock.
When you first fire the bike up carefully check the headers for temp. All should heat up evenly. Cooler headers indicate a problem with that cylinder.

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post #3 of 19 Old 07-27-2019, 04:48 PM Thread Starter
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Quote:
Originally Posted by Islandboy View Post
Check for signs the FPR has failed.
Make sure your coil connectors are all good.
To eliminate the power commander as the problem you really need to disconnect it and take the bike back to stock.
When you first fire the bike up carefully check the headers for temp. All should heat up evenly. Cooler headers indicate a problem with that cylinder.

Peeked for some info on the FPR...yet no smell of petrol or excessive fuel consumption. ANother part that has never been changed on my bike though, so its probably due (at close to 70k now).

Ill check the headers warm up evenly shortly.

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post #4 of 19 Old 07-27-2019, 05:23 PM Thread Starter
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The headers heated up fairly evenly. Middle two seemed to get the hottest the quickest, but all were close in their warming upon a cold start.

Will ride more after some grub and see if the problem resurfaces - wasnt evident for the brief 10 minutes ride just now.

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post #5 of 19 Old 07-28-2019, 06:48 PM Thread Starter
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All was fine and dandy yesterday...Took the beast for a good 45 minute ride, and the issue did not resurface. Was fine on the way to work this morning also.

Strange saga eh? Could the damp have gotten in somewhere then dried off taking the issue with it?
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post #6 of 19 Old 07-28-2019, 07:25 PM
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Quote:
Originally Posted by thegutterpoet View Post
All was fine and dandy yesterday...Took the beast for a good 45 minute ride, and the issue did not resurface. Was fine on the way to work this morning also.

Strange saga eh? Could the damp have gotten in somewhere then dried off taking the issue with it?
It does sound like gremlins.
If it doesn't happen again, I'd say water gremlins.

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post #7 of 19 Old 07-29-2019, 09:04 PM
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Just in that rev range...makes me thing of vibrations. I had a pc3 issue where i would lose throttle intermittently. There fi light would come on. Then it seemed to go away if i could get the revs up. Turned out the splice connector from the pc3 to the rdbk wire at the ecu had severed the red and black wire.
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post #8 of 19 Old 07-30-2019, 12:59 AM
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Yeah I wasn't sold on that wire tap connector.
Spliced and soldered the wires together on my bike.

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post #9 of 19 Old 07-30-2019, 07:09 AM
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Quote:
Originally Posted by Oranjvoodoo View Post
Just in that rev range...makes me thing of vibrations. I had a pc3 issue where i would lose throttle intermittently. There fi light would come on. Then it seemed to go away if i could get the revs up. Turned out the splice connector from the pc3 to the rdbk wire at the ecu had severed the red and black wire.
I had the opposite problem during the original installation.
I was so concerned about overly squeezing and damaging that thin wire, I didn't squeeze hard enough to break through the insulation and get a proper connection.
Another nip with the pliers took care of it.

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post #10 of 19 Old 07-30-2019, 01:26 PM
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Quote:
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Yeah I wasn't sold on that wire tap connector.
Spliced and soldered the wires together on my bike.
Cheesy connector for sure. I took the pc3 off and the bike runs just fine on the stock tune for my needs. Maybe one day I'll get a USB cable and see what it has to offer.

How are the sparkplugs on OPs bike? Spark problems can get better with revs, but tend not to come and go.

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post #11 of 19 Old 07-31-2019, 05:51 PM Thread Starter
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Quote:
Originally Posted by Oranjvoodoo View Post
Cheesy connector for sure. I took the pc3 off and the bike runs just fine on the stock tune for my needs. Maybe one day I'll get a USB cable and see what it has to offer.

How are the sparkplugs on OPs bike? Spark problems can get better with revs, but tend not to come and go.
Had them changed 14 months back...and all is running fine again now. returned to the trusty Erions map which works perfectly on my 919. I'll just keep quiet and hope that problem does the same!

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post #12 of 19 Old 08-01-2019, 05:24 PM
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Best of luck bud

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post #13 of 19 Old 08-02-2019, 03:02 AM Thread Starter
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Same thing happened on the trip home from work...not instantly, after all week fine, this morning fine. It was when I was trying to cruise at around 2500rpm at 60kmh. Jerky, felt like sudden, brief small cuts in fuel delivery. Absolutely vanishes with the throttle open zooming up the rpm, but when back to that 2500ish spot and a little beyond, trying to keep it constant, jerky.

Headed off to see my pixie niece for her birthday an hour after and it was fine in all areas, and even better on the way home.

Bike is at the mechanics on Monday to fit the new fork springs, so perhaps I should ask him to splice and solder the wiretap connection? Or check something else?

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post #14 of 19 Old 08-02-2019, 03:13 AM
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That's a bugger.
Get your mechanic to at least check that wire tap. Also check the PC111 negative connection at the battery. Thin black wire.
Make sure the coil connections are good. They are a push on spade terminal and can come loose.
Make sure your fuel tank is venting. Do this carefully. After a brief run, carefully open fuel tank. There should be no vacuum.
You could be due an in tank fuel filter.
Check vacuum hoses on throttle bodies.
Check all sensor connections.
Good luck mate.

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post #15 of 19 Old 08-03-2019, 12:52 AM Thread Starter
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Quote:
Originally Posted by Islandboy View Post
That's a bugger.
Get your mechanic to at least check that wire tap. Also check the PC111 negative connection at the battery. Thin black wire.
Make sure the coil connections are good. They are a push on spade terminal and can come loose.
Make sure your fuel tank is venting. Do this carefully. After a brief run, carefully open fuel tank. There should be no vacuum.
You could be due an in tank fuel filter.
Check vacuum hoses on throttle bodies.
Check all sensor connections.
Good luck mate.
Thanks as always, comrade...and the bike was absolutely perfect all day. six different outings and running perfectly. Odd saga eh? I will mention the above to the mechanic on Monday. More money, but need to get to the bottom of the problem.

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post #16 of 19 Old 08-03-2019, 01:10 AM
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Rule out a failed FPR also. There should be no fuel in the vacuum lines running off the throttle bodies at cylinders 2 and 3.
Bad fuel?

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post #17 of 19 Old 08-04-2019, 03:50 AM Thread Starter
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Havent had time to check much, comrade...but rode to Sandringham today, a decent 50km round trip, then a series of smaller trips, probably covered close to 100km all up, and no problems whatsoever, not even a hint...

I will mention the issue to the mechanic tomorrow, though am unsure if he will know what I mean by the wire tap with the diagrams which I dont have handy, though could print and take with me tomorrow I suppose. Without having the problem to show, it could be a pricy game for me to say it needs solving!

Wouldnt even call the issue intermittent, twice in a week. When I ride a lot everyday.

So of these things -

Get your mechanic to at least check that wire tap. Also check the PC111 negative connection at the battery. Thin black wire.
Make sure the coil connections are good. They are a push on spade terminal and can come loose.
Make sure your fuel tank is venting. Do this carefully. After a brief run, carefully open fuel tank. There should be no vacuum.
You could be due an in tank fuel filter.
Check vacuum hoses on throttle bodies.
Check all sensor connections.
Good luck mate.


Should I ask the mechanic to check the lot? Or is that likely to be hours of work added to my estimated 1.5 to 2 hours for the fork spring replacement?

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post #18 of 19 Old 08-04-2019, 04:17 AM
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My advice...take the seat off, lift the tank and get familiar with your machine. It will make diagnosis of future problems easier and cheaper.
All the issues I've listed, with the fuel filter the exception, are easily checked by yourself. If your bike is still running the original fuel filter it came out of the factory with then what's the harm in popping in a new one. The actual part isn't all that expensive but paying someone to put one in would be.
Your bike problem could be any number of things. You just got to start eliminating potential issues. Start with simple and easy things first.

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post #19 of 19 Old 08-04-2019, 04:32 AM Thread Starter
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Quote:
Originally Posted by Islandboy View Post
My advice...take the seat off, lift the tank and get familiar with your machine. It will make diagnosis of future problems easier and cheaper.
All the issues I've listed, with the fuel filter the exception, are easily checked by yourself. If your bike is still running the original fuel filter it came out of the factory with then what's the harm in popping in a new one. The actual part isn't all that expensive but paying someone to put one in would be.
Your bike problem could be any number of things. You just got to start eliminating potential issues. Start with simple and easy things first.
Ill just stick to the forks work tomorrow, though will discuss the issue and ask him to check the wire tap, nothing more. Then get onto the advice you have given me, mate. Always appreciate your advice! And may well head to Tasmania in the coming months, hire a bike and fly through some forests, would be great to collide if I do!

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