919 and the infamous not firing 2/3 cold header don't think it's the fuel pres reg... - Wrist Twisters
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post #1 of 4 Old 06-14-2019, 01:04 AM Thread Starter
Join Date: May 2018
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919 and the infamous not firing 2/3 cold header don't think it's the fuel pres reg...

Bought the bike a few years ago, Sept 2016, 2002 Honda 919 with about 20k miles.

Fast forward year and a half later... I put about 13k miles on it ran like a champ, then during a ride it just starts running like crap, rough on the low, no power in high rpm range, mid range barley managed 70 mph on the highway; more throttle bike would slow down...

So I figured bad fuel injector/s, quick bike bandit search, 170 bucks for 1, GTFOH ebay found a fuel rail and 4 injectors along with a FPR, 80 bucks... once it comes I swap out the whole assembly... Couple short rides around everything seems fine.

Finally go on a longer ride and same thing, seems like it's not running on all 4... I limp it home, park in and.... eventually I devise a method to clean the fuel injectors. Eventually get all 4 done, everything seems fine... reinstall the new used fuel rail... A few short rides everything seems fine, Finally go on a longer ride, hour there hour back, same thing happens not running right... limp it home... parked...

To the best of my knowledge it is a cali model or had evap can- Removed one of the prior owners.
Had a PC3- removed for process of elimination
When I bought from previous owner, had a muzzy with maybe cbr1000r exhaust header-very quiet
Installed stock header and pipes which had the bafflectomy-modified...
Currently stock headers with a single pipe instead of the Y with a Yoshi can on the right side.
Still has the pair valve and had the flapper mod

The last time I tried to fix this, I am also getting a bad MAP flash from the ECU... missed vac line, goofed a connector... IDK, starts a little rough, but after about 10 seconds the idle would even out... That was than... now rough idle, or dies...

Eventually I realize I should troubleshoot each thing, not the whole bike, which fuel injector/cylinder is not right? so rather then burn my finger I spray water on the header after it's been running for like a minute 1 and 4 hot, 2 and 3 cold... I have the FPR that came with the bike, but don't think either are bad, I hooked each up and the diaphragm doesn't seem damage, as both hold vacuum... Not sure what other ways you can check them??

Aside from taking it into a shop and leaving it there saying call me when everything is fixed, I'm about out of idea's... Don't want to buy a new FPR and not fix the issue... Any idea?

I was figuring just to rule it out getting a new FPR...

Question about that, once new one is installed, does the cold not firing... go away immediately? Or take some time, If I change the FPR and nothing changes clean the fuel injectors and retest?

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post #2 of 4 Old 06-14-2019, 04:01 AM
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I noticed you didn't mention anything about your ignition system. Are you aware one coil supplies spark to cylinders 2 and 3. I would rule this out.
Check the connectors to the coil supplying it with power. They just push on and can come loose.
You could swap coils about to see if trouble moves to other cylinders. To rule out coil failure.
You can inspect the FPR vacuum hoses into cylinders 2 and 3 throttle body for fuel. Should be none.
If you haven't done already sort out that loose vacuum hose. It only runs right after 10 secs because of some emergency programming in the ECU that comes into play. It's not right.
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post #3 of 4 Old 06-14-2019, 02:28 PM Thread Starter
Join Date: May 2018
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Already swap the coils, as I had same coil that were in a nighthawk, 20 years later still using same parts... And I said... I already checked to see if under a vacuum if fuel was leaking, nope

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post #4 of 4 Old 06-14-2019, 05:55 PM
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Bugger...I was hoping it was something simple like a loose coil lead.
Maybe pop cyl 2 and 3 spark plugs out. Wet or dry? Check for spark.
Go right over all your vacuum hoses, all hooked up and sealing.

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