Suzuki ATV Forum banner
1 - 14 of 14 Posts

·
Registered
Joined
·
58 Posts
Discussion Starter · #1 ·
How are the cheap Amazon petcocks? I am going to rebuild the carb. The quad seems to bog badly at full throttle. So....I am going to clean the carb, but wondering if the petcock is an issue also. Anyway to diagnose this properly or are these aftermarkets petcocks usually junk?
 

·
Administrator
Joined
·
9,531 Posts
Is it a vacuum style fuel petcock or the simple non vacuum type, On/Off/Res..? I’ve personally had no experience with the ones from Amazon, or know of anyone that has tried them.
 

·
Registered
Joined
·
10 Posts
I would first rebuild your carb and see if your problems clear up. They should flow enough fuel, but it could be a bad one or have a restriction. I would also check the fuel line and make sure it is not pinched or restricted in any way.
 

·
Registered
Joined
·
58 Posts
Discussion Starter · #4 ·
I went away on vacation for a week and the quad won't start. The petcock has Res, ON and PRI. I switched the petcock to PRI and disconnected the hose that is on the right side or rear most side of the petcock. This lines goes directly to the carb. The other hose on the petcock goes to the fuel pump. When I switch to PRI, NO GAS leaks out of that right side hose that goes to the carb. I thought this would send gas directly to the carb. Am I missing something? When I look in the tank, the gas volume is clearly above the petcock inlets.
1. Is this a vacuum petcock
2. Should I be getting gas to leak from this hose in PRI?
 

·
Registered
Joined
·
58 Posts
Discussion Starter · #5 ·
I think I may be able to answer some of my own questions. I think this is indeed a vacuum petcock. That right sided hose that I removed seems to be the vacuum line. When we removed the LEFT sided line, we get gas in the PRI position at the Petcock. So, how do I get gas to flow out at a line at the carb to confirm gas is getting to carb?
 

·
Administrator
Joined
·
9,531 Posts
Those vacuum operated fuel petcocks only flow fuel in the “On” or “Res” position when the engine is being cranked or running. In the “Pri” position, which is short for prime flows fuel regardless of if the engine is running or not. This setting is mainly used if you should need to prime the fuel system or used in troubleshooting.

If you want to see if fuel is reaching the carb disconnect the main fuel feed at the carb. Now get someone to crank the engine while you watch for fuel flow. If the system is working correctly fuel should pulsate out the line, unless you switched the fuel pump to a aftermarket electric one.

However, if fuel comes out the vac line or port where you removed that line then the fuel petcock is bad and needs to be replaced. Or you can bandaid fix it by plugging both the vacuum port on the fuel petcock and the vacuum port on the carb and run the bike with the fuel petcock set to the “Pri” position. Just make sure to return the valve back to the “On” position whenever the engine isn’t running as this setting still acts as a fuel shut off. Failure to do so will result in oil contamination as the “Pri” flows fuel regardless of if the engine is running or not as I previously noted at the beginning of my post.
 

·
Registered
Joined
·
58 Posts
Discussion Starter · #7 ·
Thanks. I will certainly check. I also notice that they have a fuel shut off under the seat. It looks like a simple ball plastic ball valve that would be on a lawn tractor like this.


I wonder if this flows enough fuel for the thing in the first place.
 

·
Registered
Joined
·
148 Posts
If I am not mistaken you can feel the suction on your thumb from the fuel pump when you pull the right (i mean correct) fuel line while turning the engine.

I wound up in the UP deep in the woods. That is what the mechanic said.
 

·
Administrator
Joined
·
9,531 Posts
That shut off valve must of been added by the previous owner. Cause I’m pretty sure that is the first time that I’ve ever seen that. I know I don’t have that shut off valve on my 300. And I’ve never heard of anyone else over the years mentioning this shut off valve either. So I’m pretty sure it was added after the fact.
 

·
Registered
Joined
·
58 Posts
Discussion Starter · #10 ·
Oh, there is no doubt it was added. He did this because of fuel in the gas and he then rebuilt the carb. But, I don't think he was that good at it. I am going to ditch the shut off and ordered an OEM petcock. This way I can start fresh. But, after watching a Youtube video, it seems that if the gas level is below the fuel pump, even on PRI you won't get gas to flow by gravity. Kind of a pain in the but. Right now, I have no fuel flowing. I will get rid of the shut off, add gas and she if it will start. That will get me back to where I purchased it and then I will likely rebuild the carb and replace the petcock with OEM.
 

·
Administrator
Joined
·
9,531 Posts
That’s sounds like a good plan of attack. Let us know how you make out.
 

·
Registered
Joined
·
58 Posts
Discussion Starter · #12 ·
I got the quad running. The plug was fouled. But, I still DO NOT understand this damn petcock. After it was running for a few minutes, I removed the fuel line from the carb. It appeared that it would run fuel in the PRI setting and the ON setting. RES would not run fuel. I let the quad sit overnight and now I cannot get fuel from the hose no matter what setting it is on and the gas level is full, so it should gravity feed correct? Bottom line, how the hell do I check if this petcock is working right. I have a new OEM one on the way, but I want to understand how this thing is supposed to work. I thing the fuel pump is what is throwing me off. On our suzuki ozark, PRI flows fuel and on and res do not unless you crank.
 

·
Administrator
Joined
·
9,531 Posts
Here, read this thread from a member named Tim. The thread is from 2012, but he explains how the fuel petcock works by taking one apart and posting images. This might help clear a few things up. If you have any further questions we’ll try and jump and answer them.

 

·
Registered
Joined
·
58 Posts
Discussion Starter · #14 ·
Well, I put in a new OEM Petcock, took the carb partly out and adjusted the pilot screw. It was 4 screw turns out. I set it back to factory 2 5/8. The quad runs fantastic now. I am not even going to rebuild the carb at this time. It runs perfect. No bogging and purrs like a kitten. Thanks for help all.
 
1 - 14 of 14 Posts
Top