I have a question/problem I'm hoping you guys can help with...
I have a '99 M900 that I put FCR 41's in two years ago to help solve a performance problem. The problem is when I hold the throttle open for a few seconds, it starts to cough and sputter and bog down like it's not getting enough gas. It has, on occasion, actually stalled as well. After it sits for minute, it starts fine and runs but will do it again if I get on it. It doesn't seem to be any different if the weather is warm or not. Last year I put in a new fuel pump (standard Mikuni replacement) and it seemed to help for a while but now is doing it again. I've read some articles saying that if my valves are out of adjustment, that it could cause something like this as well. Not sure if that's accurate or not in my case. I have not checked them either way yet.
Here's my question...
Will upgrading to some new 2V coils (from CA Cycleworks) solve this problem? Or is there an option of putting in a larger, more powerful fuel pump? It just seems like it's starving for gas. I know enough about motors to be somewhat dangerous but would appreciate any help anyone can provide.
Thanks,
[bang]
If it is starved of fuel, improving the spark with CA coils won't help that problem. That said, I would still buy them, they rock! Had them on my 97 750 for a year or so. If you had mikuni's still, I would guess it's the needles ovaled and you're actually flooding a bit. But since it's FCRs I have no clue ;D yet to fit my 39s.
Maybe Koko64 may have some more ideas?
It sounds like a vent issue, or possibly a fuel pump issue.
Check to see if the vent lines coming out of the rear of the tank are kinked.
Based on your post it really sounds like delivery issue.
I'd pull the fuel line from the carbs and crank the motor to be certain fuel spurts out. It won't be constant.
If it doesn't it's the pump.
If it does it could be a vent problem.
Let us know.
I got exacly the same symtoms :'(
I've got the ca cycleworks coils. And they are not the reason
my somptoms:
When it gets really hot the bike stalls like its not getting any gas ... I stop let the bike cool down and it runs fine ....what I've ruled out so far :
Bad gas .....mmm. thats just a myth
carbs ...... spark plugs are a butiefull coffee brown
coils ......... I've put another set of coils...same symtoms
Fuel pump...if defective the bike would not start back
vacuum hose for the fuel pump.... I've change it ....not the problem...
From my understanding the problem seams to be electrical....... to mutch eat =no ignition
What is left
ignition modules.... my best bet [thumbsup]
pick up coils......got new ones 300$ [roll] not istalled wet
magneto....unlikelly but there a wire there fot the ignition
Direct replacement Mikuni fuel pump delivers enough volume for a V8. Wouldn't hurt to check anyway. Soft fuel lines can collapse, particularly the line from the pump to the carbs. +1 on kinked lines. If you still have the vacuum fuel shut off it could be a problem. How is the fuel filter?
Thanks everyone for the response.
- I have checked the fuel lines and they appear fine. I think I'm going to replace them any way. It's a cheap fix.
- The fuel pump is new last summer.
- I will try the "pull the fuel line from the carbs" thing. It should work since the fuel pump is new but who knows?
- The bike is kept in a clean/dry garage so I don't think moisture is problem.
- I replaced the fuel filter at the same time I did the fuel pump.
- Also, fresh premium gas.
- ducatigirl100 have you ever noticed that your starter button will not work every once in a great while? Like when the bike is cold and you have to hit the starter a couple of times, does yours "miss" or not work? I just noticed that happened the last time I started it. I turned the key off and back on and it worked. Weird ??? (also the first time running for the year which took quite a few attempts)
This certainly sounds like a delivery problem but why? What could I be missing?
Thanks again,
Yes . when I push start ..sometimes it just does the "click" from the selenoid.... but the starter motor dosent turn... I have a motogadget gauge ...and it tell the voltage in real time .... the reason the starter motor dosent turn is the voltage drop when I press start. It can drop to 9v ! So the starter motor dosent turn....
But this problem is not related it comes from ....well.... just tring to start the bike too mutch...
if you add a delevery problem the bike would not start ...period....
out of specs valves ... also not an issue...because the bike would .. backfire and make all sorth of... "put,put,prout" noise's ;D
A collapse vaccum hose the goes from the fuel pump to the intake of the vertical cylinder is a god thing to check... if the line is to "soft" it will collapse when the full pump is functioning
The fuel pump works like a vacuum .... it suck air in order to work... its the same thing if you try to suck in a stray .... to mutch vacuum will collapse the stray if its to soft and no Pepsi will come up... as an example ;D [popcorn]
I've change that vacuum line... I've chaged that line to a really hard rubber line ...not results
I'm looking more to the elecrical side now....
Do the fuel flow test and bypass the vacuum tap if you have one as was suggested.
Vacuum taps are a common failure you can search here.
CCW coils are a good upgrade you will notice over old oem coils.
You're in good hands as DP and I seek Howies advice.
Good luck and let us know how you go.
Gday 100. :)
Check the small plug to your solenoid. They come loose. Failing relay under the seat can cause that symptom. Even a sticky solenoid. Maybe corrosion at your switch, starter terminals, etc?
Quote from: koko64 on May 16, 2015, 07:53:46 AM
Gday 100. :)
Check the small plug to your solenoid. They come loose. Failing relay under the seat can cause that symptom. Even a sticky solenoid. Maybe corrosion at your switch, starter terminals, etc?
I look at the plug that goes to the selenoid ... its a old one and I add to put a ty-rap to old the plug in place ..... ahhhh these old bikes ;D
Me too. [thumbsup]
OK, I've replaced the fuel lines and it still does it. Seems to be even worse than before. I'm about to remove the line from the carb to see if the fuel pump spurts or not. Should have done this before I know.
So while it did this I was trying to really pay attention to what else is going on and it seems like it's missing. It's not a total audible miss as much as something I can feel. Kind of jerky.
Thoughts?
Do the fuel flow tests suggested to identify or rule out a fuel supply issue. If there is plenty of fuel flowing then you can turn your attention to other issues like ignition/spark.
Quote from: koko64 on May 23, 2015, 03:30:42 PM
Do the fuel flow tests suggested to identify or rule out a fuel supply issue. If there is plenty of fuel flowing then you can turn your attention to other issues like ignition/spark.
this... [thumbsup]
Ok, just pulled the fuel line off the carb and I have plenty of fuel coming out. Never even got the chance to hit the starter gas was coming out so much.
Next?
Set up a tin to catch the fuel and crank it to see if the fuel pulses out (it should). If it doesn't you could be starving for fuel at speed but getting by low down with a full tank of gas.
You gotta carefully tick off each item checked to be sure.
Thanks, I'll try it tomorrow. Time for dinner [drink]
I'll let you know what happens.
I have good news and bad news.
Good news - fuel pump seems to be alright. Started the motor and when I give it gas, more comes out like it should.
Bad news (2 things) - First is that I broke off the plastic nipple on the carbs that the fuel line connects to. I'm hoping that I can just replace that. But, that means I have to pull off the air box and probably the carbs. [thumbsup] (I have FCR 41's so if anyone knows if this is possible, please let me know)
Second - After it ran for a second (checking fuel pump) I turn the key and it doesn't want to shut off. The starter keep going. >:( I ended up popping the seat off and disconnecting the battery. Then as a test, I connected the pos and touched the neg to the post and it sparks. WTF!
[bang] [bang] [bang] [bang] [bang] [bang] [bang] [bang] [bang] [bang] [bang]
Solenoid is stuck. Get one here https://ca-cycleworks.com/21-2988
Meanwhile, you may be able to free it up for now with a hard smack.
Thanks Howie
Next question... How do I get it appart to get that T out of there? All the pieces holding the two together come out easily except one. The one that goes into each body.
I'm I being stupid or what?
There may be a circlip or some other retaining method that you need to remove at the end of a common shaft. I honestly cant remember. There is a shaft collar which may catch. I think I was able to slide one carb back and fit the T piece with new seals without upsetting the springs and linkage at the other end iirc. It's easy to miss one of the thru bolts too. Reassembly has some issues to watch out for, so if you aren't confident to do it I would take the carbs to a good auto/carb shop that works on older cars carbs. Reassembly requires careful manipulation of the slide linkage and/or engagement slots when refitting the throttle shaft and may require the same to release the shaft iirc.
Also Power Barn overhaul carbs and I'm not sure what service SUDCO provides.
I did the same repair on a set of FCR39s a few years back, so I'm going from my notes as I don't have a set of carbs in front of me.
Update
Fuel pump is good, new fuel lines on, new starter solenoid installed.
My current setup does not include the blue velocity stacks. (I have them, they're just not mounted) Instead I have the rubber boots that are mounted to the air box like the original Mikuni's.
My question is this... If I'm having fuel delivery issues, would it be better to put the stacks on? Would this allow more air flow? If I do that, I'm not sure the air box will fit properly. The carb kit came with the air filter so I'm assuming they want me to use it. (I agree) but that means I'll have to cut my air box more to allow for the stacks to go through the holes.
Do any of you have the FCR 39/41 setup that can tell me how you are doing it?
I did get a suggestion from my dealer that said to try and switch the plug wires. If that doesn't help/work I should let it get hot, then pull the side cover (oposite of clutch) to gain access to the pick-up bearing to measure something in there that could have an effect if it's not right. I have to ask him again what I'm supposed to do because I'm apparently not getting it.
Dont use the stacks. They dont fit the airbox. The alloy adapters on the carbs fit the airbox rubbers.
Thanks Koko. I was thinking to not use them as well.
So you back to your original problem?
Your dealer is referring to the pick up coils, or ignition sensors, that signal off the magnets on the flywheel. They are located under the left engine cover. They can fail intermittently. Happened on my 97. Can be fine cold then get a bit wonky when bathed in hot oil. A failed pick up would have similar symptoms as running out of gas.
You should be able to compare resistances during different conditions. They connect up at the ignition boxes, adjacent the coils.
I stopped using the vacuum fuel pump years ago. With mine, under continuous, excessive heat (Boston traffic in summer), the internal diaphragm would leak, filling the crank case with fuel.
Been using an Airtex electric pump under the seat. It has the correct pressure and flow rate for FCR's. Bike starts easier and idles smoother.
Update : I add the same symptoms....
Got some new ignition pick-up and ajusted the timming and the bike runs fine [thumbsup]...
Here a photo [popcorn]
(http://i1121.photobucket.com/albums/l517/jfran745218/20150626_125740.png_zpsahqhpgrm.jpeg)