I recently rejetted my stock bike with 125/40 jets as described by the GS wiki. I wanted to take it out this weekend but the bike kept stalling out when I tried taking it down the street out of my neighborhood. I'm wondering if I messed up the fuel lines while putting the bike back together.
I replaced the fuel line with clear tubing a while back, I added an inline fuel filter, and replaced the o-ring in the petcock as it was leaking.
When I put the petcock on Prime, the gas used to flow freely and I could see the tubing to the carbs fill completely with gas. Now, when I turn the petcock on prime, I hardly see any flow in the tubing. Is this the cause of my bike stalling?
yep, i'd say that would starve it.
is the fuel filter pointing the right way ?
PRIME = no vacuum mess, it should flow all day.
did you set your tank mounted petcock to fully vertical ? if it's off just a little it will starve the carbs.
Make sure all lines are hooked up properly:
http://img.photobucket.com/albums/v443/jcp8832/01-02fuelcock.jpg
http://img.photobucket.com/albums/v443/jcp8832/04-06fuelcock.jpg
http://img.photobucket.com/albums/v443/jcp8832/89-00fuelcock.jpg
↑↑↑ :bowdown: :bowdown: :bowdown:↑↑↑
Thanks all who replied.
I guess I know what I'm doing after work tomorrow...I'll post the findings.
Ok, so my fuel line routing was good. The tank petcock is working, as I discovered when I forgot to turn it to OFF and disconnected the Reserve hose and dumped gas all over my bike and floor. :thumb:
Here is a pic of my inline fuel filter. According to the FLOW arrow on the filter, I have it installed correctly. So i figure either the fuel filter is no good or I don't have enough length in the fuel line between the fuel filter and the frame petcock. Any suggestions?
(http://i8.photobucket.com/albums/a18/youngbull/S1050135.jpg)
Also, my fuel line to the carb is a little long. I purposely kept it long in case I wanted to get rid of the fuel filter and go staight from the petcock to the carb. Does this negatively effect anything?
(http://i8.photobucket.com/albums/a18/youngbull/S1050137.jpg)
Stick a small funnel on the fuel line and pour some gas in to check if there's flow through the filter.
The arrow should be pointing to the petcock or carbs.Your tank petcock has 2 fuel lines one for on and one for reserve so direct to the carbs would be a compromise.Did you try opening the fuel tank cap?If you open it and fuel flows see my write up for a fix.Did you remember to turn the tank petcock back on?
http://gstwins.com/gsboard/index.php?topic=41061.0
Yep, I checked the tank petcock. I also did the following with the gas cap closed, so I assume there is enough venting.
I used the fuel overflow hose and hooked it up to the frame petcock fuel outlet to check the flow. I placed the fuel filter at the end of the fuel out hose.
(http://i8.photobucket.com/albums/a18/youngbull/S1050174.jpg)
It flows on Prime, doesn't on On/Reserve, since the bike is off and no vacuum, this is good right? When I turn it off of Prime, the flow stops and gas remains in the tube between the petcock and the filter. Is this because without the gravity from the tank pushing the liquid down, the filter impedes the flow enough that this is to be expected?
I looked at the GS wiki, and it says to place the filter inline between the tank and the frame petcock, whereas I have it between the frame petcock and the carbs. Should that make a difference and solve my fuel starvation problem?
http://cgi.stanford.edu/~sanjayd/gs500/Upgrades/FuelFilter (http://cgi.stanford.edu/~sanjayd/gs500/Upgrades/FuelFilter)
On a separate note, the Wiki picture looks funny to me, if the filter is between the tank and the frame petcock, shouldn't the filter be placed above the frame petcock?
The petcock on the frame is vacuum operated.Fuel should flow on prime all the time regaurdless of the engine running.When the engine is running the vacuum created by the engine should open the vacuum diaphram,and allow fuel to flow when it's on or res.If fuel will not flow when the engine is running then the diaphram or the button inside the frame mounted petcock is bad.I have been doing this mod while surfing the forum. http://gstwins.com/gsboard/index.php?topic=19363.0 I did mine a little different.I filled the passages with JB Weld for the prime and the vacuum passage.Now I have ON/RES/OFF.Prime became off on mine.I didn't fill the plastic cone with JB Weld.Here's a cheap solution http://gstwins.com/gsboard/index.php?topic=36958.0
The filter on my bike is the same type as yours.It was between the petcock and the carbs.The line drooped down with the filter in the droop.The weight of the fuel being above the carbs, pushes the fuel thru the line and filter.Vacuum in the carbs helps.I've never had a problem nearly running my tank dry.
I had a similar issue. I could run the bike on prime but after switching the petcock to on or reserve it would run until there was no more fuel and start to die but if I put it bike to prime it would run fine.
It puzzled me for the longest time and I check all my fuel hose routings and everything was correct. Finally I was able to determined that I had my vacuum line hooked up to the wrong carb. Instead of the inner side of the left car I had mine hooked up to the outside nipple of the rights carb.
So check you vacuum line and also check whether it may be clogged also.
Isn't there a fuel filter inside of the tank? I took the tank petcock off my bike last week and mine had a filter.
To expand on ben2go's explanation, this diagram might help to explain how the frame-mounted petcock operates:
QuoteInside the petcock is a diaphragm that acts as an on-off valve. When the bike is not running, the diaphragm blocks the fuel passage from the "ON" inlet. The "PRIME" setting bypasses the diaphragm and allows fuel to flow even if the bike is off.
If the bike is running, a vacuum line applies vacuum pressure to the diaphragm and pulls it away from the "ON" inlet. This allows fuel to flow from both the "ON" and "PRIME" inlet fuel hoses.
(http://i216.photobucket.com/albums/cc179/gs_beRto/fuelpetcockschematic.jpg)
This information was taken from a reply I originally posted in this thread:
http://gstwins.com/gsboard/index.php?topic=39168.msg439808#msg439808 (http://gstwins.com/gsboard/index.php?topic=39168.msg439808#msg439808)
Quote from: lewismug on May 07, 2008, 08:02:04 AM
Isn't there a fuel filter inside of the tank? I took the tank petcock off my bike last week and mine had a filter.
Yes, there should be a screen-type filter in there.
Quote from: lewismug on May 07, 2008, 08:02:04 AM
Isn't there a fuel filter inside of the tank? I took the tank petcock off my bike last week and mine had a filter.
There is a strainer but not a fine filter.
Quote from: beRto on May 07, 2008, 08:17:03 AM
To expand on ben2go's explanation, this diagram might help to explain how the frame-mounted petcock operates:
QuoteInside the petcock is a diaphragm that acts as an on-off valve. When the bike is not running, the diaphragm blocks the fuel passage from the "ON" inlet. The "PRIME" setting bypasses the diaphragm and allows fuel to flow even if the bike is off.
If the bike is running, a vacuum line applies vacuum pressure to the diaphragm and pulls it away from the "ON" inlet. This allows fuel to flow from both the "ON" and "PRIME" inlet fuel hoses.
(http://i216.photobucket.com/albums/cc179/gs_beRto/fuelpetcockschematic.jpg)
This information was taken from a reply I originally posted in this thread:
http://gstwins.com/gsboard/index.php?topic=39168.msg439808#msg439808 (http://gstwins.com/gsboard/index.php?topic=39168.msg439808#msg439808)
Quote from: lewismug on May 07, 2008, 08:02:04 AM
Isn't there a fuel filter inside of the tank? I took the tank petcock off my bike last week and mine had a filter.
Yes, there should be a screen-type filter in there.
That is one dam fine example of how the petcock works.I should've thought of that.
Quote from: ben2go on May 07, 2008, 10:56:31 AM
That is one dam fine example of how the petcock works.I should've thought of that.
Thanks! The diagram took me ten minutes to draw in
MS Paint, so I figured I should get a second use out of it. :icon_mrgreen:
The vacuum line is attached to the correct spot on the carbs. Before the re-jet, the fuel situation was fine between the tank and carbs. I guess the vacuum hose could be plugged, but I'm thinking that shouldn't effect the flow on the Prime setting.
So after reading all the suggestions the only thing I could come up with is maybe having the hose too short between the petcock and the fuel filter is creating enough resistance, in a short distance, to restrict the flow of fuel to the carbs.
I think I'm gonna try this when I get home.
(http://i8.photobucket.com/albums/a18/youngbull/gs500.jpg)
(14-second MS Paint drawing, feel free to distribute amongst your friends)
It could be getting air locked.
Quote from: OCyoung on May 09, 2008, 01:04:58 PM
The vacuum line is attached to the correct spot on the carbs. Before the re-jet, the fuel situation was fine between the tank and carbs. I guess the vacuum hose could be plugged, but I'm thinking that shouldn't effect the flow on the Prime setting.
So after reading all the suggestions the only thing I could come up with is maybe having the hose too short between the petcock and the fuel filter is creating enough resistance, in a short distance, to restrict the flow of fuel to the carbs.
I think I'm gonna try this when I get home.
(http://i8.photobucket.com/albums/a18/youngbull/gs500.jpg)
(14-second MS Paint drawing, feel free to distribute amongst your friends)
Before you move the filter, maybe you should try using a temporary line without any filter? That way you could confirm that everything else is working ok and the filter is definitely to blame.
I tested the fuel filter and the petcock separately, they're both fine. Plenty of fuel was filling my water bottle when I tested them.
Y'know, I'm thinking ben2go's airlock suggestion might be valid. Whats a good way to prevent this when I put all the lines back together?
Make sure no air can be trapped in the filter.All it takes is inclining the tapered end of the filter plus keeping it a little lower than the frame mounted petcock. :thumb: