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10-03-2015, 06:05 PM,
#1
One car won't send fuel, swapped parts no change
I am having trouble with one carb on my 2002 vstar 650. It is not sending any fuel into the rear cylinder. I have verified this by temp on pipes as well as visually. I am getting spark on that cylinder.

I tried taking it apart and cleaning all the jets; they all looked good but cleaned them anyway, no improvement. The float is letting it fill the bowel but still no spray into the cylinder.

Then I tried swaping the removable parts of the jets over to the back carb still no improvement. The back carb gets the fuel first so I do not see it being fuel rail, pressure or delivery.

If I pressure up the vent tube I get fuel spraying back up through a jet into the bowel so I know that part is ok as well.

Very frustred; any help would be greatly appreciated.
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10-03-2015, 06:17 PM,
#2
RE: One car won't send fuel, swapped parts no change
(10-03-2015, 06:05 PM)sillybrian Wrote: I am having trouble with one carb on my 2002 vstar 650. It is not sending any fuel into the rear cylinder. I have verified this by temp on pipes as well as visually. I am getting spark on that cylinder.

I tried taking it apart and cleaning all the jets; they all looked good but cleaned them anyway, no improvement. The float is letting it fill the bowel but still no spray into the cylinder.

Then I tried swaping the removable parts of the jets over to the back carb still no improvement. The back carb gets the fuel first so I do not see it being fuel rail, pressure or delivery.

If I pressure up the vent tube I get fuel spraying back up through a jet into the bowel so I know that part is ok as well.

Very frustred; any help would be greatly appreciated.
is the diaphram slide moving freely? all it takes is a pin hole or an air leak in the diaphram to stop the slide from lifting the needle out of the jet, on constant velocity carbs if you look through the throat you can see if the slide is lifting up. the only other thing i can think of is a severe vacuume leak at the intake joint stopping the slide. does the engine at least idle ok?
Lightbulb dumb bikers don't get to be old bikers
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10-03-2015, 06:24 PM,
#3
RE: One car won't send fuel, swapped parts no change
(10-03-2015, 06:17 PM)pauli466 Wrote: Thanks, I looked at the diaphragm side, it seemed ok; as well physically moving it does not have any fuel spray out into the carb. When I roll on the throttle it does move back and forth. I could try swapping the diaphragm sides to see if it improves.
(10-03-2015, 06:17 PM)pauli466 Wrote: I have also tried blocking the entire inlet to build max vacuum in the carb throat, same thing it is still dry, no fuel going through.
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10-03-2015, 06:42 PM, (This post was last modified: 10-03-2015, 06:45 PM by pauli466.)
#4
RE: One car won't send fuel, swapped parts no change
(10-03-2015, 06:24 PM)sillybrian Wrote:
(10-03-2015, 06:17 PM)pauli466 Wrote: Thanks, I looked at the diaphragm side, it seemed ok; as well physically moving it does not have any fuel spray out into the carb. When I roll on the throttle it does move back and forth. I could try swapping the diaphragm sides to see if it improves.
as long as it's moving it ok, but when you see it moving is the needle moving with it? if the clip on the needle fell out the slide will move but the needle wont. also be very carful with diaphrams they get pretty fragile with age. if they seem a little brittle or stiff don't touch em.
(10-03-2015, 06:17 PM)pauli466 Wrote: I have also tried blocking the entire inlet to build max vacuum in the carb throat, same thing it is still dry, no fuel going through.
if the carb isn't letting fuel in at idle or when throttling you might have a clogged float needle seat. did you try switching that also?
Lightbulb dumb bikers don't get to be old bikers
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10-03-2015, 07:21 PM,
#5
RE: One car won't send fuel, swapped parts no change
Still no luck, I double checked the diaphragm, it is in excellent condition, took apart the needle all is in tact. Pulling it in and out the needle travels with it.

I have checked the float valve, it lets fuel in ok. Did this both with draining the bowel but also with the bowel open it flows quickly into the area.

I had sprayed up through the vents and seen the carb cleaner shoot through. This is getting very frustrating.
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10-03-2015, 08:04 PM, (This post was last modified: 10-03-2015, 08:18 PM by pauli466.)
#6
RE: One car won't send fuel, swapped parts no change
(10-03-2015, 07:21 PM)sillybrian Wrote: Still no luck, I double checked the diaphragm, it is in excellent condition, took apart the needle all is in tact. Pulling it in and out the needle travels with it.

I have checked the float valve, it lets fuel in ok. Did this both with draining the bowel but also with the bowel open it flows quickly into the area.

I had sprayed up through the vents and seen the carb cleaner shoot through. This is getting very frustrating.
man i'm not easy to stump but i'm stumped on this problem. there's not much more i can tell ya without having the carbs myself. maybe some of the other guys on the forum have some ideas. but i'm stuck like you now. do the pms screws still have the plugs on em, if not remove em and spray some cleaner in em. maybe you can get it to a least idle right. also don't sepperate the carbs from each other. that should only be done if absoloutly nessary. is the compression good on that rear cylinder? and is the plug like bone dry when pulled.an engine will run on carb cleaner did you try spraying some into the rear carb with the eng running to see if it starts firing
Lightbulb dumb bikers don't get to be old bikers
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10-03-2015, 08:10 PM,
#7
RE: One car won't send fuel, swapped parts no change
Not sure what you mean "PMS" screws.
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10-03-2015, 08:25 PM, (This post was last modified: 10-03-2015, 09:02 PM by pauli466.)
#8
RE: One car won't send fuel, swapped parts no change
(10-03-2015, 08:10 PM)sillybrian Wrote: Not sure what you mean "PMS" screws.
the pilot mixture screws are on the aircleaner side of the carbs with little brass colered plugs over them.there about the size of a pencil eraser

(10-03-2015, 08:25 PM)pauli466 Wrote:
(10-03-2015, 08:10 PM)sillybrian Wrote: Not sure what you mean "PMS" screws.
the pilot mixture screws are on the aircleaner side of the carbs with little brass colered plugs over them.there about the size of a pencil eraser
to remove the plugs you drill a very small hole through them (go easy you don't to hit the pilot screws under them) then you screw a sheet metal screw into the hole and pull the plugs off the PMS screws. you can remove PMS screws and clean the orfices with carb cleaner. before you remove them seat them in very softly and count the turns so you will know how many turns out they need to be when reinstalling them. just don't crush em into the seats when you turn them in and you'll be fine. the stock setting is usually 2 1/2 to 3 turns out from the seated position.

(10-03-2015, 08:25 PM)pauli466 Wrote:
(10-03-2015, 08:10 PM)sillybrian Wrote: Not sure what you mean "PMS" screws.
the pilot mixture screws are on the aircleaner side of the carbs with little brass colered plugs over them.there about the size of a pencil eraser

(10-03-2015, 08:25 PM)pauli466 Wrote:
(10-03-2015, 08:10 PM)sillybrian Wrote: Not sure what you mean "PMS" screws.
the pilot mixture screws are on the aircleaner side of the carbs with little brass colered plugs over them.there about the size of a pencil eraser
to remove the plugs you drill a very small hole through them (go easy you don't to hit the pilot screws under them) then you screw a sheet metal screw into the hole and pull the plugs off the PMS screws. you can remove PMS screws and clean the orfices with carb cleaner. before you remove them seat them in very softly and count the turns so you will know how many turns out they need to be when reinstalling them. just don't crush em into the seats when you turn them in and you'll be fine. the stock setting is usually 2 1/2 to 3 turns out from the seated position.

https://www.youtube.com/watch?v=wyspAHrMbb8 this link will show you how the carb is supposed to work
Lightbulb dumb bikers don't get to be old bikers
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10-03-2015, 10:16 PM,
#9
RE: One car won't send fuel, swapped parts no change
That did help, I took it out, everything looks ok with it and put it back in. After seating it I backed it out 2 1/2, then a little more after a test start. It seems to be spraying some fuel into it now and the cylinder is getting warm but not hot. I will pack it in for the night then mess with it again in the morning.

Lets hope this is what the problem is. Thanks for your help.
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10-05-2015, 08:09 PM,
#10
RE: One car won't send fuel, swapped parts no change
It is spraying a small amount of fuel in now; but I still don't have the cylinder firing. I will post a new topic on that part of it since it is not in the fuel side of things now. But for some reason I cannot get starting fluid to fire in that cylinder. I took the spark plug out and put a new one in but before I tested it on the block side and have good spark; put it in the engine but still nothing firing.
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