can only go at 1/2 throttle - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
Carbs and Fuel System
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post #1 of 9 (permalink) Old 07-19-2009, 11:32 AM Thread Starter
 
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Angry can only go at 1/2 throttle

yesterday I went to a bike show in Carlisle Pa. The bike ran fine getting there, but getting home was a whole different story. As soon as I got on the interstate and got in the fast lane to pass the bike just started to act like it wasn't getting gas. It was surging and the speed dropped from around 70 to 45 real quick and eventually came to a stalled engine after about 3/4 mile of acting up. We let it set for a couple of minutes and it started up. a friend said if it starts to act up pull the choke and see if it helps. It acted up and I PULLED THE CHOKE and was able to get it up to 65 on level highway any hill would slow it down. I manage to make it home, I sat down started reading the forms here and this morning I pulled the tank took the diaphragm out of the petcock capped the vacuum line put it back together as a gravity fed and i still have the same problem, only able to go at 1/4 throttle. I also looked for the carb vacuum line to see if it was crushed. I only found a hose leading from between the carbs to the area of the RH air filter. it actually stopped behind the filter and not attached to anything. Does anybody have any clues? ALSO, IF IT IS IN MY NEUTRAL IT WILL REV FINE IT ONLY SEEMS TO ACT UP WHEN IN GEAR UNDER A LOAD. COULD IT BE SPARK PLUGS????

Last edited by JUSTHAVINFUN; 07-19-2009 at 11:41 AM. Reason: FORGOT SOMETHING
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post #2 of 9 (permalink) Old 07-19-2009, 11:43 AM
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It sounds like you are the latest victim of the infamous "phantom gas syndrome".

To read up on others' experiences with this problem, you can use the "search" function in the above menus, and search for related threads there.

This is pretty much a fuel vapor lock issue, and seems to occur the most during hot weather, and when the fuel tank is below 1/2 full.

One way to deal with it is simply let the stalled out bike sit for 5-10 minutes, and then curiously it will start right back up again.

Another solution is to simply open up the gas cap (with a spare key) while the bike is still in motion (and during the initial sputter); this seems to (obviously) kill the problem outright b4 the bike totally stalls out.

Let us know if the above does not work for you......

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post #3 of 9 (permalink) Old 07-19-2009, 11:49 AM Thread Starter
 
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It does it right away as soon as i leave my driveway could i vapor lock that fast? And i seems like it is really sucking up the fuel
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post #4 of 9 (permalink) Old 07-19-2009, 12:00 PM
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If it is happening immediately after you try to drive away...then it could indeed be something else....others will weigh in with other suggestions.

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post #5 of 9 (permalink) Old 07-19-2009, 12:15 PM
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I would drain the tank completely, and clean out the tank, drain the carbs. Then try the Sea foam in the gas to help clean the carbs out. Sea foam does a great job in clearing out problems with the carbs being contaminated. The line to the right ear intake should be cut on the end at 45 degrees to make sure it does not bottom out. If it does it will affect the way the bike runs.

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post #6 of 9 (permalink) Old 07-19-2009, 07:11 PM
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Maybe Lance should chime in on this, when I took my bike in for inspection I had them check out my hesitation and they replaced the air switch that sits under the seat by the gas tank. They also found one of the diaphrams in the carb needed replaced. Seems to run a whole lot better now.

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post #7 of 9 (permalink) Old 07-20-2009, 09:51 AM
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when you left the bike show , did you leave with the same gas in the tank that you got there with or did you fill up ? you might have gotten bad gas. if it raqn good getting there and ran bad when you left that is a possability .

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post #8 of 9 (permalink) Old 07-23-2009, 10:34 PM Thread Starter
 
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well I held a pair of pliers against my front carb and hit the pliers with a dead blow hammer, guess what? it worked the bike is running fine had it up to 92 mph with no problem. I am currantly running seafoam through ths tank of gas.
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post #9 of 9 (permalink) Old 06-11-2011, 03:59 PM
..have a vulcan good day!
 
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Quote:
Originally Posted by JUSTHAVINFUN View Post
well I held a pair of pliers against my front carb and hit the pliers with a dead blow hammer, guess what? it worked the bike is running fine had it up to 92 mph with no problem. I am currantly running seafoam through ths tank of gas.
Very smart and easy fix.. I like it ! Seafoam time !

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...have a vulcan good day!
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