# Middle Carburetor



## zrsteve (Aug 28, 2014)

I took my GTO to the shop to have a new headliner installed. I noticed when I came to stop signs the car was running rough and stalling, like the choke was stuck shut. When I got to the shop I pulled the air cleaner from the middle carb and could see fuel actually flowing into the carb. Not sure what's causing this or how to make a fix. Suggestions?


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## RT-1 (Mar 21, 2012)

Your float is stuck. It happens fairly frequently with the newer high volatility gasoline as it basically boils out of the bowl every time you shut it off leaving residue that eventually builds up to the point where you are. Pull the top off the carb and clean the bowl and needle/seat assembly with carb cleaner.


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## zrsteve (Aug 28, 2014)

RT-1 said:


> Your float is stuck. It happens fairly frequently with the newer high volatility gasoline as it basically boils out of the bowl every time you shut it off leaving residue that eventually builds up to the point where you are. Pull the top off the carb and clean the bowl and needle/seat assembly with carb cleaner.


Same thing is happening to the front carb with the engine at idle.


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## allpawl66 (May 9, 2008)

What style needle / seats you using ? Fuel pressure ? Fuel filter ? Ethanol fuel ? Float settings ?


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## BearGFR (Aug 25, 2008)

:agree: What allpawl66 suggested. What you're describing sounds like too much fuel pressure going into the carbs. It's a little bit suspect that it started happening after the shop visit, but also suspect that two carbs started having the problem at the same time. Don't let those facts distract you from basic troubleshooting though. If you're experienced and/or not afraid to do that work yourself, opening them up and inspecting (cleaning, and maybe replacing) the needle and seat assemblies plus verifying/adjusting the float levels is a relatively simple (and certainly inexpensive) task. It's also a good idea to install a permanent fuel pressure gauge in the engine compartment. Having that information available goes a long way towards helping to identify and eliminate causes of suspected fuel delivery problems. I don't have the specs on tri-power handy, but with a QJet anything more than 5-7 psi inlet pressure is skating on thin ice as far as being enough to force the needle off its seat and cause the problem you're seeing.

If you don't find an obvious cause internally, the next step ought to be verifying your fuel pressure.

Bear


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## geeteeohguy (Feb 2, 2008)

Probably junk in the needle and seat assemblies. Pretty rare for a stuck float on these carbs. Good thing is, these carbs are dead simple compared to a Q-jet. You can pull the top off and check the needle and seat and float easily. Sometimes, tapping on the top of the carb at the front with a screwdriver handle will jar whatever's in the needle and seat assembly loose and cure the problem. Again, very easy to check the needle and seat out. With the float raised, you should not be able to blow thru the fuel inlet on the carb (with your mouth, NOT a shop air hose!).


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## zrsteve (Aug 28, 2014)

Thanks for all of the info. I'll start with the floats. I'm sure there is no correlation, but I just replaced the tin fuel lines to the carbs with SS lines.


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## geeteeohguy (Feb 2, 2008)

Very likely related. Especially if you used any of that teflon tape on the inlet threads!!! My money is on crap (tape?) on the needle/seat assemblies. Never seen one of these brass floats 'stick'. Seen them sink (with a hole in the solder joint) and seen them out of adjustment, but haven't seen them 'stick'. They work like a toilet bowl float. The float on top of the fuel and close the needle valve. If a piece of crud is on the needle valve, it will not seal, no matter how hard the float applies pressure.


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## zrsteve (Aug 28, 2014)

Well I did use Teflon tape on the brass block threads that go into the front carburetor and the brass fitting that screw into the main carb. These are the two carbs that are giving me problems. Thanks GEETEE

I haven't had a chance to investigate the problem as I'm replacing the interior of the car IE instrument bezel refurbished, seats rebuilt, new carpet, new headliner and an aftermarket console.


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## geeteeohguy (Feb 2, 2008)

I'm betting that when you take the carbs down, you'll find teflon tape in the needle and seat assemblies, causing your problem. Don't use that stuff on fuel lines unless you have the precision of a surgeon. Much better off with nothing or a _microscopic_ amount of the teflon paste.


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## zrsteve (Aug 28, 2014)

Thanks again. I haven't started tearing the carbs apart yet, putting the car interior back together.


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## GFT 12:17 (Jul 26, 2014)

I would like to start by wishing all the other fathers out there a Happy Father's Day.

I was hoping to take my GTO out for a spin this morning, but couldn't get my car to start. It turned over for a second or two, then died. I tried to restart, but not luck. It seemed as if it was missing something (like fuel - but not sure). However my hood was up and I noticed my center air filter had swelled and was saturated with gas. After taking off the air filter to see what was going on I tried to start the car again. Gas was spitting out from the top of the carb. 

I took the carb off and started to take it apart. The intake needles seemed clean as I could see light through them. Is there a simple way to clean them? I wondering if I sucked something into the carb somewhere? Thinking about a fuel regulator to adjust the pressure? How can I tell if my float is stuck? I blew some air through the fuel intake to the part below the float hinge and it seemed unclogged? I have the neoprene, do I need to adjust it?


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## GFT 12:17 (Jul 26, 2014)

Follow up: I purchased a can of carb cleaner, took the center carb apart, sprayed everything real well and put it back together. Car started right up... I wish I knew what I did (specifically), but I think I dislodged a piece of crud or something. I didn't mess with any adjustments as it was running great before hand.


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