Time to do some diganostics - Wrist Twisters
 
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post #1 of 16 Old 02-26-2010, 11:09 PM Thread Starter
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Time to do some diganostics

Well on my last trip about 450 miles, my bike started to act up on me. When ever I'd crack the throttle open it just flat out dies out. It'll cruise just fine but a quick throttle movement will just about stall it out. before the trip and even half 1/4 of the way through it I could easily pull out from a light with the front tire up in the air, no more.

At first I figured it was bad gas because I had to get some from a questionable station, put some dry gas in it.... nothin. Ran that tank almost dry twice now, once the fill up was 4.6 gallons, you just can push it much further that that with out a gas can on the back. The problem persists.


Now naturally my next guesses are the FPR and the TPS, I'm leaning more towards the FPR as the diaphragm is a know week point on these bikes and is documented several times failing and would certainly cause my issues, and even as sofa king pointed out, my shit is running crazy rich.

Moral of the story, tomorrow morning I'm lifting the tank and checkout out the vacuum line and spark plugs. I bet 2&3 are fouled out. I felt the headers tonight as the bike was warming up, they all get hot, but 2&3 take considerably longer.

That is all.

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post #2 of 16 Old 02-27-2010, 05:00 AM
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Sounds like you've got a good idea of whats going on there. I work on cars for a living but have yet to tackle any diagnostics on a fuel injected bike, kind of looking forward to it. I browsed through the FSM and it seems the 919 runs a very similar fuel injection system to the pre OBDII Honda cars. Fuel pressure regulator or TPS seems like a solid place to start, if it had an O2 sensor that would be worth looking at too.

Good luck, I wish you a speedy diagnosis.

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post #3 of 16 Old 02-27-2010, 05:31 AM
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Sounds like you nailed it. Fouled plugs. Now just find out in the Fuel Pressure Regulator is the source.

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post #4 of 16 Old 02-27-2010, 06:58 AM
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Check battery terminals and all grounds -

Has anything been done to the bike recently?

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post #5 of 16 Old 02-27-2010, 08:58 AM Thread Starter
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Nope, no new mods, bike was running great then half way throught the trip it went to crap, I already pulled the battery and put it oin the tender overnight. Are there any other grounds other than the battery on this bike?

and yeah the bike is pretty much an obd1 system w/ no O2, just like my honda crx (engine, and ecu swap) so I've had a lot of experience with the set up

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post #6 of 16 Old 02-27-2010, 09:10 AM
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Quote:
Originally Posted by Jeef View Post
Nope, no new mods, bike was running great then half way throught the trip it went to crap, I already pulled the battery and put it oin the tender overnight. Are there any other grounds other than the battery on this bike?

and yeah the bike is pretty much an obd1 system w/ no O2, just like my honda crx (engine, and ecu swap) so I've had a lot of experience with the set up
There's a ground under the gas tank.
And like I said elsewhere, check the air filter and for loose wiring before getting into the more difficult/unlikely stuff.

"Towards the end of the vid, it looks like she may have had a bafflectomy." - MarylandMike
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post #7 of 16 Old 02-27-2010, 09:13 AM
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Quote:
Originally Posted by Jeef View Post
I felt the headers tonight as the bike was warming up, they all get hot, but 2&3 take considerably longer.

That is all.
Hmmmm, 1 & 4 on are on coil, 2 & 3 on the other. Fuel pressure affecting the two inside cylinders to the point of easily detectable header pipe heat differentials as compared the outside pipes, strikes me as highly improbable. Still wise to check the fueling side, but I suspect that ignition for the 2/3 combo is at play, and beyond the simple plug fouling you suspect.

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post #8 of 16 Old 02-27-2010, 10:12 AM
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Quote:
Originally Posted by mcromo44 View Post
Hmmmm, 1 & 4 on are on coil, 2 & 3 on the other. Fuel pressure affecting the two inside cylinders to the point of easily detectable header pipe heat differentials as compared the outside pipes, strikes me as highly improbable. Still wise to check the fueling side, but I suspect that ignition for the 2/3 combo is at play, and beyond the simple plug fouling you suspect.
The FPR pulls vacume from cyl 2 and 3 and the FPRs are known to tear the diaphragm and pull fuel into those two cylinders.


Dan
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post #9 of 16 Old 02-27-2010, 10:25 AM
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Quote:
Originally Posted by voodooridr View Post
The FPR pulls vacume from cyl 2 and 3 and the FPRs are known to tear the diaphragm and pull fuel into those two cylinders.

aaaahhhhhh, good to know and this is one I am going to squirrel away !

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post #10 of 16 Old 02-27-2010, 07:58 PM Thread Starter
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yeah so I pulled her apart today, starting with the airfilter, sure enough there was a puddle of fuel laying in the bottom of the box, pull the vacuum line off the FPR and it reaks. I recon I'm picking a new one up tommorrow. The main reason that I figured the FPR was the problem is because there has been more than a few bikes on here with the same problem.

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post #11 of 16 Old 02-27-2010, 11:29 PM
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Glad you found your problem. What year is your bike?

"Towards the end of the vid, it looks like she may have had a bafflectomy." - MarylandMike
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post #12 of 16 Old 02-27-2010, 11:50 PM Thread Starter
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I'm pretty sure thats the problem, I'll know for sure tomorrow when I track down a new one... and its an 03 with roughly 30k miles on it.

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post #13 of 16 Old 02-28-2010, 12:45 AM
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Good work, Jeef! Sounds like an FPR might be a nice spare to travel with, just in case...I haven't heard of any other real problem pieces with the 919 that fail often, other than normal maintenance items... If there are, maybe we can make a sticky that lists those for future easy reference?

Well, fire the engines! Spur this iron space-pony on!

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post #14 of 16 Old 02-28-2010, 06:07 AM
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Quote:
Originally Posted by The Shadow View Post
Good work, Jeef! Sounds like an FPR might be a nice spare to travel with, just in case...I haven't heard of any other real problem pieces with the 919 that fail often, other than normal maintenance items... If there are, maybe we can make a sticky that lists those for future easy reference?
I think the list is here. The FPR one is near the top in the heads up section, called Gas Fouled Plugs

https://wristtwisters.com/naked-bikes...19-owners.html

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post #15 of 16 Old 02-28-2010, 03:18 PM
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Quote:
Originally Posted by marylandmike View Post
I think the list is here. The FPR one is near the top in the heads up section, called Gas Fouled Plugs

https://wristtwisters.com/naked-bikes...19-owners.html
That's the really great thing about this place...we stand on the shoulders of those who have gone before.










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Well, fire the engines! Spur this iron space-pony on!

"The Shadow"
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post #16 of 16 Old 03-01-2010, 12:47 PM Thread Starter
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Verdict is in... This morning I found two of the prongs on the tps sensor to be broken. With some creative engineering I got a Tps sensor off of a honda car to work on it. It is only a temporary fix till I can get the proper tps in but it works for now. I still suspect the Fpr is seeping... but it may also be the Pairs system using my air box like a catch can.

Here is the liquid in the box...





and here are the differences in the TPS sensors, notice they mirror each other with the direction and springs



You can't pull the lever off, its glued to the post and it snaps very easily, but you can work the spring off the bike tps onto the car tps





then the next part is you can't mount it through the std. holes or even in between the the two prongs inside that are intended to hold and move the lever. The lever needs to be on the bottom right side of the prongs and the screws have to go thusly


Next we need to calibrate, break out the trusty volt-o-meter and find a nice ground, and for the positive I insert a safety pin in the middle wire pin area and use the loop in the pin to hold the positive feed.



and look for 4.5v on Wot and .5v on closed

As I said this is not meant to be a permanent solution, just a band-aid for now.

and boy does she rip now with the new plugs and a good TPS, one more note, you may think you stock tps is riveted on, its not, those are head less screws the back out very easily with a screwdriver and a hammer, angle the screwdriver and tap to remove, then replace them with proper screws, I used hex headed ones I had laying around.

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