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Discussion Starter #1 (Edited)
Brand new (chinese) carb off amazon.

I tried the default adjustment and tried to adjust the idle screw clockwise and counter clockwise 1/4 turn with no changes. Quad will start to run on choke, idle pretty high. If I give any throttle it will bog down. It will run high then the idle will come down for about 10 seconds then stall out. I've tried to clean it a bit with carb cleaner if maybe I had bad gas, but I get the same issue. I tried to seat the screw all the way then loosen it ~2.6 turns (per the manual) and I get the same response.

Any suggestions?

1998/1999 LTF4WDX
 

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What model/year Suzuki is it..?


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Cheap Chinese knock off carbs sometimes make things worse. The high revs sound like you might have a vacuum leak between the air box and carb. Maybe sure everything is 100% air tight. Another possibility is a faulty fuel petcock. When it goes bad it can lead to all sorts of problems such as: stalling, poor idling, back firing, power loss, hesitation. Though this wouldn’t cause high revs which leads me to suspects you have a vacuum leak as I mentioned. Check for leaks and go from there.


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Same advice as ajl719, trie spray wd40 (or equivalent) on intake boot when idle, and verified rpm variations.
For the faulty fuel petcock/fuel pump possibility, try supply fluel directly to the carb (by gravity).
 

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If you have to use the choke to keep it running it's probably lean. Either air leaking in somwere or it's not getting enough fuel.

Your Chinese knockoff carburetor may not be jetted right for your quad. Or the mixture screw may need turned out farther.

Could also be a vacuum leak. I'd start the engine. Then spray some carb clean or starting fluid on the intake between the carb and engine. And on all the vacuum lines. If it has a leak you will hear the idle go up or down depending on what you spray it with.

Could also be an issue with the fuel petcock or fuel pump. It also could be a clogged fuel filter or in tank fuel strainer.

The vacuum leak is probably easiest to check for so I'd start there.
 

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Discussion Starter #7 (Edited)
So with the criticism of the Chinese Carbs I've decided to go back to the OEM. I rebuilt it a while back but wasn't getting any luck with it.

1. I tested the Peacock by taking off the line flowing into the fuel pump. Gas flows fine.
2. I can see that I'm getting gas into my carb as the fuel filter is see through. I took it off and a ton of gas came out so looks like that is flowing fine.
3. I tried to start it with the old carb, and I could not get it to run at all with our without the choke.
4. I sprayed either/starting fluid and it barley pops.


My next steps are to take the oem carb apart again and clean all the jets and ports.
I'm sure I have a vacuum leak somewhere since I don't know what the three ports are on the top. (labeled 1,2 and 3)
The previous owner just ran a hose to jump 1 and 2 and had nothing on three.

I assume one goes to the fuel tank cap? I don't have a nipple on the back of my pea cock for the others?

What would you guys do from here?




 

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Clean out the OEM carb/jets real well then buy yourself a carb rebuild kit. I’d try that then go from there.


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So with the criticism of the Chinese Carbs I've decided to go back to the OEM. I rebuilt it a while back but wasn't getting any luck with it.

1. I tested the Peacock by taking off the line flowing into the fuel pump. Gas flows fine.
2. I can see that I'm getting gas into my carb as the fuel filter is see through. I took it off and a ton of gas came out so looks like that is flowing fine.
3. I tried to start it with the old carb, and I could not get it to run at all with our without the choke.
4. I sprayed either/starting fluid and it barley pops.


My next steps are to take the oem carb apart again and clean all the jets and ports.
I'm sure I have a vacuum leak somewhere since I don't know what the three ports are on the top. (labeled 1,2 and 3)
The previous owner just ran a hose to jump 1 and 2 and had nothing on three.

I assume one goes to the fuel tank cap? I don't have a nipple on the back of my pea cock for the others?

What would you guys do from here?




with #3 open.....that was part of the problem with too much air.

I think #1 is a vent which is just a open ended hose ran up under the shifter
#2 goes to the fuel pump
#3 goes to the petcock

FYI that filter is probably letting in TOO much air.....you need to use the original filter in the box with lid and the rest of the duct work...these bikes are real finicky on this.
 

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Some fuel petcocks do not have the vacuum port. If yours was replaced with this style you should be able to cap it's vacuum port on the carburetor. Any local auto parts store should carry vacuum caps to plug the port.

The vent on the fuel tank cap doesn't go to the carburetor. It's just a vent. Usually would have a line running from the cap down through the plastic panel around the shifters below the speedometer. If you zoom in on this pic of mine you can see the vent line coming off the gas cap.
 

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Discussion Starter #11
First off, thank you all for your help. This thing has been quite frustrating, I'm usually good with small engines.

can anyone confirm? In the image below I have A running to my fuel pump, and B should be capped off (since I dont have a spot on my peacock)? It doesn't show clearly in my manual.

 

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Is your fuel petcock the non vacuum style, On/Off/Res..? Or the vacuum style fuel petcock, On/Pri/Res..? With it being a ‘98/‘99, I would think it should have a vacuum operated style fuel petcock, but I could be wrong or it could of been changed at some point. If your fuel petcock is the non vacuum style, simply cap the vacuum port on the carb.


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Discussion Starter #13
it has the ON/PRI/RES but doesn't have any nipples for another vacuum connection.

I'll make sure tomorrow but could be crazy.
 

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What doesn’t have a extra nipple(s)..? The carb..? One vac line should run from the fuel petcock to the carb. The other vac line should run from the fuel pump to the carb. Their should also be a vent line running from the carb up under the shift panel. If you have the correct carb/fuel petcock all lines should have a place to hook up to. Not sure if I’m missing something.


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it has the ON/PRI/RES but doesn't have any nipples for another vacuum connection.

I'll make sure tomorrow but could be crazy.
The petcock with ON/PRI/RES has a vacuum line ......on the backside
 

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Discussion Starter #16 (Edited)
Finally some good news!
I rebuilt the original carb, adjusted the pilot screw to 2.6 turns from seated and put the airbox back on. I don't have a second nipple off the back of my petcock like some of you say I should (maybe I'm missing a nipple see pics below), and I do have a ON/RES/PRI peacock. I blocked off the two vacuum ports off the back of the carb (z and y on the picture) and the port off the front (x in the picture) , the other line runs to my fuel pump. I tried to start the quad and noticed I wasn't getting any fuel to the fuel filter (even after a lot of cranking). So i ran a line directly from an external gas tank and it started, ran and idled pretty well.

So now my next steps are to get the fuel to flow. I dont think the petcock is the issue as it flows fine when i unplug it from the fuel pump and drain it into the pan. I did rebuild my fuel pump last year but I guess i could throw another one at it for 30$? Just making sure my fuel pump inlet is on the right and outlet on the left? Once again i appreciate your help getting this far.

current setup


my petcock



stock photo brand new
 

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Your petcock has to have been modified by someone because fuel will not flow in the ON position without the engine running. That back plate is for the vacuum operated valve that opens the petcock when it is turning over or running.
 

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That is a bizarre looking fuel “Petcock”. Looks nothing like mine. And your quad is close in age to mine. Should be relatively close in design. At this point, I tend to agree with TC regarding your fuel “Petcock”.


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Discussion Starter #19
Assuming the petcock does flow fine, I guess I'll have to dive into the fuel pump not allowing flow. I'll try messing around with the fuel lines and see what I can figure out.
 

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Discussion Starter #20
The previous owner must of modified the petcock because no matter what setting it is gas free flows.

I still was not able to get the quad to run using the fuel pump. odds are its all gummed up again even though I rebuilt it not too long ago. with the quad running from another fuel source and a fuel line running from the pump into a bucket no fuel came out. I then tried to unplug the vacuum line from the carb to the fuel pump and apply pressure from a vacuum pump, still no fuel flowing.

I'll have a pump by tomorrow so I'll see if i can swap it out.
 
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