how to clean out acceleration jets quadrajet carburator

Rough Idle

This tin be caused by several things, just there is i item often missed past the rebuilder and that is the idle tube. These are very small passages and get clogged easily with ethanol residuum. Use thin wire to make clean out the passages completely. Blow out with compressed air. A whistle with air will indicate a make clean passage. If wire doesn't practise it, try heating the outside of the passage and and so blow air through. There may be a small air restrictor in the passage that makes getting through with wire difficult.

Carburetor is flooding.
Gas is running out of the top, or you go a strong gas odour? This is a sign of flooding. What is flooding? Merely, there is too much gas getting into the bladder bowl.

Here is a listing of items to check when this happens (non in any society):

Test the needle & seat for leaking. 80% of the time this will be the problem. The needle may have been damaged while adjusting the bladder, or dirt from the gas tank got back into the carburetor. Wait here on how to test the needle & seat.
Fuel pump pressure – check with your motors manual for the right pressure. New pumps are especially suspect. four.5 lbs would be a get to if yous tin can't observe the spec.
Bad float – For contumely floats, estrus up some h2o to prior to boiling, then immerse the float. In that location should be no bubbles. Nitrophyl floats have to be weighed. 6.5-7.5 grams would be groovy.
Check bladder level
Make sure float isn't binding – move it up and downwardly by hand and see if you feel anything communicable.
Brand sure bladder doesn't rubbing somewhere.
Does the seat have a gasket?
Did all of the old gasket get removed?
Wait for whatsoever cracks around the area the seat screws in.

Engine is Uneven, or Surges

Timing, dwell & idle adjustments.
Await for any fuel brake – check for kinks in the fuel line.
Replace any fuel filters – At that place is normally ane in the fuel inlet of the carburetor and often in that location will exist an in-line fuel filter.
Vacuum leak – Use spray carburetor cleaner and spray around the base of the carburetor and any vacuum lines. If the RPM smooths out, so y'all found the trouble. There could also be a leak at the intake manifold.
Check the float level.
The ability valve may be sticking. It needs to motion up and down freely.
Clay in the system – take the height off the carburetor. If y'all come across dirt in the lesser of the fuel bowl, rebuild the carburetor, make clean the fuel lines & the gas tank.
Main metering jet may exist the wrong size. If yous take been running the carburetor for awhile, then this won't be the problem. Jets don't vesture out. Make certain the jets are not loose, or plugged.
Secondary throttle valve alignment.

Missing Tubes

Sorry about lack of knowledge and poor terminology. What I was referring to pickup tubes are telephone call the master well air bleed tubes (ii inside tubes ) and secondary accelerating well tubes( the 2 exterior tubes) fig. 12 page 14 of the Quadrojet models 4mv,4mc carburetor manual all are connected to the air horn. My carb. doesn't take the secondary accelerating well tubes. The transmission is not specific to marine nevertheless your video is and it shows all four tubes. Looking through your parts department I found pt # 17-91 Rochester carb. contumely tube. It'southward description states that there are 2 that stick out from of the lesser of the float bowel top. I don't have these. My question is should I have the secondary accelerating well tubes and if I exercise is that the correct part # ?

He needs to have all four tubes, 17-91 is one of those numbers.

Quadrajet Carburetor Kits

Idle Compensator is Missing
The Hot Idle Compensator, when used on 4MC and 4MV Quadrajet carburetors (View C) is located in a sleeping accommodation at therear of the carburetor bladder basin side by side to the secondary bores. Its purpose is to offset the enriching effects acquired byexcessive fuel vapors during hot engine functioning.
In a perfect world the Idle Compensator should be installed on those applications that need information technology. Since the compensator part is non being produced you lot don't have any choice but to run without it. Yous won't accept any problem unless you lot get into a loftier heat situation, or use your air conditioner.
Notation: Fifty-fifty though your carburetor may take a identify for the compensator to sit, it doesn't hateful information technology came that way. It was used on vehicles with air conditioning.

Adjusting Idle Mixture Doesn't Change Anything
This is usually indicative of a problem with either as well much air, or not plenty fuel (in the idle circuit).

First of all be sure you lot are adjusting the idle mixture at the idle RPM. If the RPM is likewise high, the idle circuit will exist bypassed.
Be sure the throttle body gasket isn't leaking. Spray carb cleaner around the outside of the gasket. If the RPM changes then you found your problem.
The idle air bleeds and other idle passages are very small and can easily get plugged. If the carburetor was sitting for many months, then the ethanol residue could exist plugging things up.
Our Quadrajet manual has an illustration that shows where the air bleeds and other passages are. Y'all need to follow each one with compressed air to exist certain they are open.
Take the idle mixture screws out and see if they are plugged.
See above for the 'crude idle' article.

Quadrajet High Speed Lack of Ability

Lack of power is often caused by electrical, or engine wear. Nosotros won't talk over here, instead we will concentrate on what problems the Quadrajet may have.

Fuel filters are dingy, or plugged – replace any in-line filter and the filter at the carburetor fuel inlet.
Bladder level may be besides low – fix to specifications.
Float isn't dropping far plenty to open the needle fully.
Power valve may be dirty, or sticking. Make sure the power valve moved up and down easily and there is a jump under the valve.
Float is catching when moving up and downwardly. The float pivot may be worn. Motion the float up and downward past paw to see if y'all feel anything communicable.
Needle is sticking in the seat. A impairment viton tip can cause this along with some chemicals added to the gas. NOTE: Do not apply whatsoever force per unit area to the needle when adjusting the float.
Fuel pump may non be putting out enough pressure.
Cars that sit for months at a time will damage the carburetor. Ethanol absorbs water and left sitting, the water settles to the lesser of the float bowl and accelerator pump well. This will corrode the bottom of the bladder basin and the pump well. Damage to rubber parts can also occur. The cure is to use non ethanol gas and drive the car more.

Engine Hesitates

This can be caused past ane of several things, including electrical system problems.

Timing, dwell & idle adjustments.
Accelerator pump itself may be bad. The loving cup curled, or is damaged. Some chemicals added to the fuel, or left in the carburetor can crusade this.
Exercise a quick test of the accelerator pump circuit.
The pump passage way to the master belch may be plugged.
Superlative of the carburetor to the bladder bowl gasket may be leaking due to bad, or wrong gasket, or a warped bladder bowl, which is not uncommon on the Quadrajet.
Bank check the bladder level.
Carburetor mounting bolts are loose.
Secondary throttle valve alignment.

Polish the pump well with crocus cloth, or 2000+ sand paper. Apply a couple of dabs of white lithium grease. Today'south gas has footling lubrication. A piffling grease will help.

What to look for when your Rochester Quadrajet is flooding.

The number one trouble to look for is leaks around the needle and/or seat. Many rebuilds are ruined by a dirty fuel tank, or filter. Besides make sure all old gasket remainder is gone.
New viton tip needles sometimes are covered with residue, causing information technology to not seal until started several times. Wiping with mineral spirits tin can aid.
Bank check the float for leaks – For brass floats, rut up some water and merely prior to humid immerse the float. The float volition rut upward inside and if at that place is a hole, air volition chimera out.
Nitrophyl floats (looks like plastic), are tested by weight. vi.5 – viii grams, depending on which float it is.
Move the float upward and down by hand – Practise yous experience annihilation catching?
Test your fuel pump – new pumps are particularly suspect and often accept likewise much pressure. Consult your repair manual for the specification, but 4 to 5 lbs is boilerplate for most carbs. If your flooding started after a rebuild, then skip this one.
Tin can you run into gas dribbling out of the principal belch, or venturi while at idle? This would indicate the primary discharge, peradventure the check ball, not sealing. This is more of an over rich condition than flooding, simply flooding to i person may be different to another person.
If your carburetor hasn't been rebuilt recently, then considering doing then. Most carb problems are attributed to dirt. A carburetor that has been sitting for half dozen or more months tin likewise be coated within with gas that has turned to varnish.
At that place is a pull prune that connects the float needle with the float arm. Be sure the clip is not routed in one of the pocket-size holes. Information technology should be around the outside of the arm.

Protect your engine with ETHANOL DEFENSE

And yet some other troubleshooting guide here.

I have a Rochester Quadrajet Marine Carburetor #17059286. It appeared to be flooding at idle and the fuel was leaking excessively from the throttle body linkages (on both left & right side). I assumed the carb needed to be rebuilt and the leaking was normal (from a bleed in the carb) when flooded. I rebuilt it using a kit I ordered from you. I reinstalled the carb and I'chiliad having the aforementioned effect of fuel leaking from the throttle body linkages. In your youtube video (Rochester Marine Carburetor rebuild part 3 of 3) at four:00 you mention not usually having to take apart the thottle body to supervene upon bushings. My question is: Exercise you recollect I should supersede the thottle body linkage bushings? And if so, practice you carry the kit? I retrieve this is what I demand to practice. However, I read a post online that said the fuel at the thottlebody should already be atomized, and should therefore not leak out the linkage,and that would bespeak that the carb is flooding due to the bladder not being adjusted properly. I gear up the float to 3/xvi like the instructions stated.

Your problem is not bushings. The carburetor is only puking out too much fuel. The bushings are replaced merely if you lot have excessive complimentary play in the throttle shaft. Flooding fuel will leak out anywhere it can and onto the throttle valves and out the shaft is the 1st identify fuel likes to go.

Too much fuel boils down to getting too much in the float bowl. Did you test the (contumely) float for leaks? Immerse the bladder in hot water and if at that place are any leaks, information technology will bubble. If you have a Nitrophyl bladder (black plastic kind of affair), supercede information technology. They blot fuel over time.

Did you put the fiber washer where the seat screws into the float bowl.

Many times after rebuilding a carburetor and afterwards re-starting the engine, crud from the tank and the fuel lines will rush up to the carburetor and into the needle & seat causing it to stick open. Take the carburetor apart and launder out the needle & seat and endeavour over again.

Manually movement the float up and downwards and sentinel for whatever kind of rubbing, or catching. Likewise watch the needle to make sure it is move straight up and down and non getting caught up.

Too much fuel pump pressure could be holding the needle open. Any chance you replaced the pump with a new one? New pumps are always suspect because they come from China and they don't seem to care almost specifications very much yet.

These are just a few ideas, but bottom line is that too much fuel is getting into the bladder bowl.

HARD STARTING WHEN COLD

Starting time lets start by learning how to start a classic motorcar with a carburetor.

Press the throttle down in one case, and so let up. The accelerator pump will eject an actress bit of gas into the intake. The engine needs a bit of help when cold. You can check this with the engine off past looking downward the carburetor and pump the throttle once to see the squirt.
The choke valve volition close once yous pace on the gas. Make certain it is closing when cold.
It may take a few seconds of cranking to fill the carburetor (if low).

Now what to wait for if you are having problems.

Every bit mentioned in a higher place make certain the choke valve is closing. Some will open just slightly so it doesn't choke out.
Is the fast idle sitting on the higher step of the cam. If the fast idle isn't working then the engine may die subsequently starting. It needs the extra gas and the extra air to start.
If the carburetor is losing too much gas overnight, then it may exist percolation. See this folio.
Test the fuel pump (new pump particularly). Y'all desire to make sure the force per unit area is where it should be. In that location is besides a book test if you can find the spec for that.
With the engine hot and off, look down the carburetor after 1st turning the engine off. Do yous run across gas dribbling out of the main discharge. If and so, then the check may be leaking. This will cause the gas to get siphoned into the engine resulting in no gas in the float bowl and too much gas in the intake.
The gas cap should be vented. A non vented gas cap on a arrangement that needs a vent volition cause gas to get siphoned out of the bladder basin. Simple to test by loosening the gas cap after turning the engine off.
If yous are using a fuel additive that contains booze, then that volition cause gas to evaporate more. We recommend using Ethanol Defense.

Hard Starting

The fuel bowl may be draining while sitting. Brand sure the fuel filter has the check valve installed.
Afterward running the engine, plow it off and await down the carburetor to run across if gas is dribbling out of the venturi. This would indicate the belch check is leaking.
If at that place is a 2nd line going to the gas tank, that is a vent. Be certain yous can blow through the passage.
Run across if the vent on the carburetor is cut off for some reason.
Engine overheating can cause the carburetor to percolate (boil the gas).
Common cold starting
- Depress accelerator pedal to the floor and release. Leave human foot off accelerator pedal and interruption a moment.

Stalls Later on Start

Timing, dwell & idle adjustments
Asphyxiate Rod
Vacuum intermission adjustment
Float level

Engine Loss of Power or Stalling in Hot Weather

Determine whether carburetor is spewing or vapor locking. This can be done by performing the following route tests in seventy to 80 degree weather.

Let the car idle in bulldoze with the air conditioning on for 10 mins.
Shut the engine off and let sit down for x mins.
Kickoff automobile and accelerate at 3/4 throttle to 60 mph. If condition is going to occur, it volition occur earlier 60 mhp.
Detect either loss of ability and/or stalling; annotation the color of the frazzle smoke.
- If frazzle smoke is black, carburetor is spewing.
- If exhaust smoke is colorless, carburetor is vapor locking.

Cold Sags, Dice Outs & Pop Backs

For all drivability complaints, check all vacuum hoses to make sure they are properly connected. A disconnected hose can allow air leaks which requite lean mixture every bit well every bit issues of improper activeness of the component operated past the hose. Also ignition contact indicate gap and ignition timing should be checked on al drivability complaints. Engine sags, dice outs and pop back during warm up are usually caused by retarded ignition timing, improper carburetor choke vacuum kick adjustment, cam index setting, fast idle speed, and mixture setting.

Retarded basic ignition timing causes pop dorsum during starting. Adjust to specification on vehicle emission control label +_ 2 i/2 deg for best engine operation.

On engines equipped with solenoid spark advance for starting bank check to make sure information technology is operating. To check disconnect leak to solenoid at bullet connector and energize solenoid momentarily with a jumper. The engine will speed upwardly approximately 50 RPM and timing advance 7 1/ii deg if solenoid is operating.

Starting Cold, the Engine Revs to Loftier RPM

Conform the fast idle.
Disconnect the throttle and effort again in social club to eliminate the linkage.
If the throttle valves were removed they may have been re installed incorrectly leaving also much air between the valves and the carb wall.
Check the fast idle cam. When warmed upward the fast idle spiral should touch the lowest spot. When cold the fast idle screw should affect about the highest spot.