If you’re an auto nut or gearhead, you know what I mean by that little extra oomph that happens when that four-barrel carburetor comes on. You’re tapping into some hidden power that the carmaker didn’t intend for you to have.
But if your engine bugs out when four-barrel kicks in or stutters when that four-barrel comes on, that extra oomph can be annoying.
So, what’s going on, and how can you fix Engine Bugs Out When Four-Barrel Kicks In?
Article Summary
What is A Four-Barrel Carburetor?
First up, review what a four-barrel carburetor is, and why you care. A carburetor blends the optimal amount of fuel and air (known as the air/ fuel mixture and abbreviated as A/F) to run your engine at the correct operating temperatures and not cause your engine to poorly combust.
A four-barrel carburetor has two primary barrel or venturis (one for low-end throttle, a second one at midrange) and two secondary barrels that kick in under fairly hard throttle, to feed the engine even more fuel and air for more power at wide-open throttle.
When it’s working well, as it should be, it is the ultimate compromise between power and efficiency, but when it isn’t, it can feel like you are a moment away from your engine falling to pieces.
Symptoms of Engine Bugs Out When Four-Barrel Kicks In Problems
If your engine is acting up as the four-barrel carburetor kicks in there are several things you can look for or listen to that might suggest something’s amiss. Here are a few:
1. Hesitation or Stuttering
Among the more obvious symptoms is a couplet stumble or stutter as the secondary barrels open. This intrusion might mean that in a transition you get only a brief richer period, as the second system attempts to supply sustained boost for the load: in other words, something that feels like imminent engine stalling or engine misfiring.
2. Loss of Power
One especially common symptom is an ‘attack of the four-barrel’, in which the spark plugs on the front two cylinders instantly take over the combustion cycle from those on the rear, causing a sudden loss of power just when the owner needs it most.
While there’s nothing better than a healthy burble and an urge to combine carousing at speed with burritos or cheaper non-Baltic options, there’s a slight catch: it can’t be relied upon for frantic getaways.
3. Backfiring
Meanwhile, a syncopated popping noise emanating from the exhaust or carburettor can be caused by an incorrect air-fuel ratio. This might be due to an overly lean or rich mixture, which can be caused by a carburettor that hasn’t been set up properly, or by other problems that affect the amount and quality of the fuel delivered.
4. Rough Idle or Poor Throttle Response
If your engine idles roughly or has poor throttle response, especially as it switches from the primary to the secondary barrels, chances are there’s something wrong with the carb. The roughness can indicate that the motor isn’t getting the correct mixture of fuel and air, so the motor isn’t running properly.
You might be able to catch these symptoms early and then repair your four-barrel carburetor before more serious engine issues arrive.
Engine Bugs Out When Four-Barrel Kicks In Causes And Fixes
Carburetor Fuel Delivery Problems
The car’s four-barrel carburetor requires more fuel when the secondaries open. If your fuel pump or fuel lines aren’t delivering enough juice, your engine could stutter.
Get a larger replacement fuel pump and hoses if your setup is slowing down your gains. Make sure you’re free of debris on your fuel-pump assembly and in your fuel lines. Is your engine rating going over 650 flywheel horsepower?
You may need a fuel-management system. It takes more than just a bigger rectangular thing attached to the car.
Boot: For a variety of reasons, these motorheads will eventually get kicked out of their car community.
Vacuum Leaks
A vacuum leak draws too much air into the system, causing a lean mixture (too much air, not enough fuel.
Repair: Check all vacuum hoses for leaks or loose fittings, then replace any damaged vacuum hoses.
Carburetor Tune-Up
Because the motor shifts breathing from the primary to the secondary barrels, it’s possible that the carburetor will need a slight adjustment.
Tune: Adjust the carburetor to deliver the right air-fuel mixture (a process that could involve adjusting float levels, mixture screws such as the idle, and or changing out jets).
Ignition Timing
When the timing is fucked up that late in the play, it seems to interfere with the four-barrel kicking in.
With precipitating factors such as high altitudes or hot temperatures, it’s possible that the mixture doesn’t have enough additional fuel to compensate for the inefficient burning at that time.
However, by adding ignition timing retard between 6 and 8 degrees (depending on where you start from), you can essentially solve the problem. Check the ignition timing and change it if necessary.
Dirty or Clogged Carburetor
Over time, the carburetor can get gummed up with road grime and dirt, which can make it hard for the secondaries to engage.
Fix: Clean the carburetor thoroughly, paying close attention to the secondary barrels and jets.
When To Seek Professional Help
If these fixes don’t work, however, you might want to talk to a professional. If the technology is complex, you could end up with issues that go beyond simple tuning, such as internal engine problems or even more advanced ‘tricks’.
FAQs on About Engine Bugs Out When Four-Barrel Kicks In
Why Does My Engine Shut off When The Four-Barrel Carburetor Kicks in?
When the four-barrel carburetor (a carburetor) kicks in, your engine might stutter or hesitate due to several issues poor fuel delivery, vacuum leaks, improper jetting (tuning of the carburetor), or incorrect ignition timing any of which can throw a fuel/air mixture out of balance.
How To Stop A Vacuum Leak That Trips The Engine Out When The Secondaries Pen?
If the problem is a vacuum leak, the vacuum hose attached to the carburetor and lead-covered hoses attached to the engine should be checked for wear, cracks, and loose connections. If any of these hoses are damaged, they should be replaced and all the vacuum hose connections should be tightened. This should return the vacuum pressure to normal and the operation should return to normal.
What To Do if My Carburetor is Dirty or Clogged?
If the carburetor is clogged or coated with dirt, clean it. Make sure you clean the secondary barrels and jets thoroughly as dirt will accumulate in those areas. Spraying the carb with a carburetor cleaner (following instructions for disassembly and cleaning by reference to the carburetor’s manual) will help you to get rid of the dirt and speed up performance. The more you take care of your carb, the less likely your problem is to recur.
When To Go Mechanic For My Engine’s Four-Barrel issues?
If, in spite of the common fixes, such as checking for vacuum leaks, cleaning the carburetor, timing the ignition, and verifying fuel delivery, the problem is still not solved, then it is time to seek some expert opinion about the matter.
Some mechanic or an internal combustion specialist will diagnose more complicated issues such as internal engine problems, or complicated carburetor tuning needs, to return your engine to its normal state.
Final Thoughts
With the four-barrel in action, if your engine bugs out it’s extremely aggravating. It’s also extremely common, with a long list of potential factors as to what might be wrong. In order to get it back and running smoothly, you have to understand what conspires to cause it and follow the diagnosis.
In the end, you’ll end up galloping down the road with a fresh surge of power, making your rabbit-in-glass-hatchback driving experience feel even better. In short, keep up with your maintenance and have your engine tuned when it needs it.
Although engines are designed to make the most of having a metric shit-ton of air funneled into each engine cycle, the fact of the matter is that they really don’t enjoy having it shoved at them under loads and at speeds that maximize the experience.
