Holley Backfire Through Carb

The problem with Holley carbs is that they are "VERY" tuneable. Idles great, runs decently when warmed up. i asked a qeustion about my Stang a little while ago, it was continuisly backfiring and i couldn't get it right, everything seemed to be right, timing, advanced timing. 30 yrs ago I had a shoebox nova with a 250 6cyl, it ran good with a clifford cam and intake w/450 holly, and a header. All in the system that would effect fuel delivery to the carb into the bowl should be verified good FIRST. Typically a carb backfire means too lean a mixture, or timing is too advanced. also there are many good working 2 barrel holleys too, just found that the ford two barrel will out perform the holley, the main reason i think is the ford carb is a larger cfm. Holley or Edelbrock Carb Welcome to Rods 'n' Sods, the most active and friendly UK Rod and Custom website. I don't let it idle long for warm up (30 seconds to a minute), choke is working and float level are set correctly. When I come to a stop the idle is off, it almost feels like it is mis firing. Re: SBC 307 backfires through carb Post by lluciano77 » Sat Dec 28, 2013 6:59 pm lefty o wrote: if its just at initial throttle tip in, very first thing i'd check is that little rubber umbrella seal for the accellerator pump. The cam is a rv cam with a 484/510 lift. How do you know if the power valves are blown ?. 335 Series- 5. I can get it to backfire through the carb in neutral by flooring it really quick. Power valves were very problematical in the older units, once you had a backfire through the carb they were usually junk. The owner of this carb is shooting for ~700 HP, so we elected to drill the PVCRs to. 6/400, 351 Cleveland - 351M backfiring through carb - 76' Ranchero, 351M, 70k Idle's fine but under heavy acceleration it hesitates and backfires through the carb and has no power, vacumm is between 16-17 Hg, timing set to 12 degrees. While the boat is in neutral, I can rev the engine up to 5-6000 Rpm, sounds perfect. Tuning tips for your E85 carburetor (crazy long) cause a backfire through the carb under acceleration). I'm suspecting bad gas as I was in a hurry and had to fill up at a suspect gas station. 335 Series- 5. Also check to see if the exhaust heat riser is stuck, allowing excessive heat under the carburetor. Odds are heat soak is boiling fuel out of carb, so initial crank bowl is WAY low if not empty, as engine cranks pump fills carb and viola, imeadiate restart, no time to boil fuel. Columbia par car carburetor adjustment. It only happens when you rev the motor, and the quicker you rev the motor the more it backfires. This illustrates the flow of clean air and heated air which, together, act upon the automatic choke mechanism to properly position the choke plate. I don't think it ran long without an air filter. I found that they are still making the 465 cfm original carburetor. Aka the ‘Towering Inferno’ carburetors, due to their nasty tendency to ignite topside if there was the slightest backfire thru the venturis below, since the (typically-leaky) fuel bowl was way up there…. 3) No gas in carb. Bronco Tech. It’s running lean. The engine was in a vk commodore that i brought but i have since swapped it into my '84 CJ-10 jeep. Carburetor Troubleshooting Guide. Moved Permanently. BACKFIRING. The following illustrations and part #'s are from Ford's master parts catalog. Backfiring that results from damaged wiring disrupts the ignition’s timing, which causes a build-up of air and fuel in the engine. Cure The Bog And Sluggish Response On Your Holley Four-Barrel Carburetor, By Properly Adjusting The Accelerator Pump Assembly. We know when they leave here they are ready to go to work for you !All of our carburetors are completely disassembled and cleaned with an ultrasonic machine. In my how-to video I will walk you through the basic principles and fundamentals of what you are adjusting and how it will impact your bike's response. The key is to resist the urge to plop a big carb on the intake to ensure good drivability off boost, and to modify the carb's internals for additional fuel flow under boost at high rpm. chevrolet71. Holes in the pipe leading to intake manifold may result in an increase inflow of air, which unbalances the air-fuel mixture ratio. hello, i have a 1968 mustang 302 stock bottom and having issues with backfiring through the carburetor and sometimes bursts flames out. Ignition timing is not perfect but should be good enough to start. Re: SBC 307 backfires through carb Post by lluciano77 » Sat Dec 28, 2013 6:59 pm lefty o wrote: if its just at initial throttle tip in, very first thing i'd check is that little rubber umbrella seal for the accellerator pump. The cam is a rv cam with a 484/510 lift. Other than the backfire bliping the throttle & the off idle transition thing- it seems to run decent Here are the specs: Holley 750 vacuum secondary (3310) Holley main body w/ choke air horn 74/84 jetting, 6. Footage taken from Holley Carburetor Installation & Tuning DVD. Steve (ff33rod) here up in the Vancouver area on the West Coast of Canada. What causes a motor to spit through the carb? most Holley carbs are rich at idle, but that does not mean it is rich once off idle. Air cleaner filter elements. Backfiring can be caused by several reasons. 3) Check fuel delivery. Check this video for idle speed adjustment. So, the popping you are hearing is not back-firing. If you have existing, non-boost referenced Holley carbs: There is a guy in Carson City, NV who will rebuild your carbs and tweak them to add boost referencing for about $350 each. It seems like when the secondaries on the carb open up, [Ford Holley 4 bbl], is when it does it, like it could be leaning out. 350 backfires through carb Hope somebody can help!Just rebuilt a 1972 chevy 350 with a new crankshaft,edelbrock torquer plus cam,torker manifold,holley carb,. Now, Holley EFI products power these cars and are dominating the performance world. 1 compression, headers, 2. The carburetor is the main component responsible for metering and delivering the air fuel mixture required for the engine to run. It wasn't clear to me from the original description. You'll need to take the carb apart and look for contaminants. Carburetor secondary plates not closing all the way. You don’t want to damaged the mixture screw just below the plug. Plus I have experienced it too. The fuel had water in it. Carburetor performance is largely based on the air-speed traveling through its venturis. This illustrates the flow of clean air and heated air which, together, act upon the automatic choke mechanism to properly position the choke plate. I've gone through and corrected them, but now I'm having odd backfire through a brand new Holley 2bbl carburetor. Check the manufacture date of your Holley carb. This product is made of high-quality materials to serve you for years to come. Fuel Inlet System. Hi everyone. There is a fuel feed problem that can cause this symptom. Carburetor Troubleshooting Guide. This allows a high pressure side and a low pressure side which in turn pushes hot exhaust gasses through the heat riser tubes into the manifold and out into the muffler. i moved it up 2 ( of 5 ) and seems to have cleared that up, but i will check the plug coloring. Our 1997 2135 has developed a intermittent drop in power/ sometimes backfires at a 3000-3200 rpm cruise. and get my mechanic to adjust the timing. The old techs I worked with in the '60's & '70's used to say the Holley was a great "wide-open throttle" carb and the Edelbrock (then Carter AFB, later AVS) was a better idle and low speed carb. You can see the number on it (it’s usually even) if you look down the top of the carb throat. Reply Silly things, one healthy backfire through the carb and there's a pretty good chance it's gone. This is all in an S-10 pickup. If you are getting backfires through the carb you are probably lean, and if it is backfiring through the exhoust you are probably rich. Hi all, I have a '64 Sprint with 289 and mild cam from previous owner. It provides the necessary fuel-air ratio to produce optimal combustion and performance. A stream out the vent is a classic stuck float problem whereas a backfire is usually a belch of air and atomized fuel. I'm a newbie boat owner and I'm looking for some advice on diagnosing a backfiring problem I'm having. it just struggles for a second when vacuum drops right out to get on the main circuit. my thoughts are the intake valves are not seating fully but a shop just installed a new head less than 600 miles ago. Check this link for backfire issues:. It is a popping resonating sound generated by a lean condition on deceleration. The 500 & 600-cfm carbs can be modified to avoid an off-idle lean condition, so they can work well on a low boost pressure single or dual carburetor set-up, but we avoid the 750 and 800 cfm AFB s on street driven blown engines because of a lean at part throttle problem that is inherent with this type of carburetor. leaked around the accel pump, on disasembly the accel pump was rotted thru. Many modern vehicles have eliminated carburetors in favor of direct fuel injection controlled by a computer. If backfiring occurs through the carburetor then adjust the idle mixture screw out another 1/8 to 1/4 turn. Real backfiring is actually the bike "spitting up" in a sense, backwards through the carburetor or intake. I also pulled the plug and it was really black. I started my boat like I do once a month to keep everything good to go. Over hauled and cleaned the carb. That means the carb fuel mixture is also slightly leaner, more prone to backfiring. Now has no power and runs rough. To preface, this is a stock 225 automatic with a "reman'd many years ago but barely used" 1920 carb that came on an engine I was gifted. If you have a carburetor older than 1992 (or you have experi-enced an extreme backfire) and expect a blown power valve, use this simple test. For assistance, we turned to an all-star panel of distinguished carb experts that includes Jay McFarland of Holley, Adam Campbell of Barry Grant, Patrick James of Pro Systems, Marty Brown of Quick. it backfires real bad (and fast) when driven, hopefully i havn't broken anything yet. I've got a popping out of the exhaust and a backfire thru the Carb that I can't seem to nail down Recently changed the dual point distributor to an MSD unit when all this started; thought it may have been lifters so I changed them and the engine is still run bad. I have a 1966 mustang gt with a 302ci motor in it. Carburetion. We get a backfire through the carb if you open the throttle quickly. Bronco Tech. Also, look for vaccuum leaks. While this carb is clearly in need of a rebuild and thorough cleaning, we grabbed it to detail the process modifying for draw-through applications. Re: 258 backFIRING through carb I had this when I had a four barrel holley on an old camaro. Use your carburetor repair kit to identify replaceable welch plugs. BACKFIRING. Crushed float. Has anyone used the power valve shield kit ( by Centek) on a holley carb to protect the valve against backfire damage ? I have a 468 BBC dual 750 tunnel setup on the hydro. The carburetor that we would recommend is based on how the customer will drive their car and the engine package that is in the car. Power valves fail due to the gas or a backfire thru the carb. Our 1997 2135 has developed a intermittent drop in power/ sometimes backfires at a 3000-3200 rpm cruise. When I do this it's a light backfire through the carb and then she'll rev up nice and quick. I asked about the way the gas was being ejected to determine if it was a backfire versus stuck float. The motor seems healthy, idles good, no smoke, sounds o. The carburetor regulates the flow of fuel and air to an engine. On the last oil change my friend cut the filter apart and found lots of metal that didn't stick to the filter mag. to check the vaccum advance take it loose and put your finger over the end of the tub and pull the lever. Repeat untill engine 'hunts' under load and then go up one size. For what it's worth on my 350 I tried a 600 Edelbrock, Holley 650 DP and spent time tuning each carb for my application after all was said & done I ended up with a 750 CFM stage 2 Jet Quadrajet on my 350. new cap,rotor,plug wires ,plugs at time of service. i keep on reading different numbers for the NKG sparks 0. If yours has an adjustable carburetor, I'd try resetting the jets first followed by rebuilding the carburetor and adjust the valves last. since i swapped carbs. I'd start with the timing. Float Circuit. I have just gone to an Edelbrock intake and brand new Holley 1848, 465 CFM carb on my stock 260 motor. Repeat untill engine 'hunts' under load and then go up one size. Carb Synch Tutorial: Ferrari 308 series By The Birdman. I have no hands-on experience with carbs, but my friend Steve hasand he has rebuilt many in his day. when i got done i put it all back together and i noticed that the secondaries dont spray fuel at all, and the engine will not idle at all if i take my foot off the gas it will die and if i give it alot of gas it will backfire. No backfiring when boat is in nuetral. Blip the throttle a time or two and observe the results. The gasket looks fine. If the rubber grommets deteriorate they can leak fuel or possibly obstruct fuel flow through the banjo bolt. Sprayed carb cleaner around base of carb, no leaks. should have thought of that myself because it's something i know of but it just didn't come to mind. Cold, no boil. Then, remove the choke plate and choke shaft and felt or foam washer in the same manner. It sounds like a little frog croaking. This task is the same for any 4150/4160-style. Carb Synch Tutorial: Ferrari 308 series By The Birdman. I did recheck the timing, I set #1 to TDC on comp, timing mark at tdc & rotor was pointing at #1 plug wire. If throttled up too quickly it backfires through the carb. 10 is the amount of degrees marked on the balancer usually there are several marks with 10 20 and 30 being numbered. If the rubber grommets deteriorate they can leak fuel or possibly obstruct fuel flow through the banjo bolt. Holley is nonfeedback type 5220. Check this link for backfire issues:. check out the us ebay for a blowthru carb set up for e85 and make sure you set up a burst plate as blow thru setups are notorious for backfires or you could go lpg also and run a 425 mixer on a holley 4 barrel base. I loosened up the dizzy and spun that arround a bit while running to cut down on the backfiring, then I set it to the correct firing order and it's ALOT better but still backfiring thru the carb at high RPM's and when revved. Drill a hole into the plug making sure not to “punch” through too fast. As I have said, it runs pretty good so it can't be far off the mark. Didn't fiddle with any adjustments besides float because it ran fine before. Holley carbs come with a standard shooter size which differs by carb list #. Generally severe enough to blow out a muffler and possibly enough to put a hole through a piston or bend a valve. 7 seems to be backfiring through the (Holley) carb but only under load. by giving it a quick stab with the throttle just above idle, in park? I did a poor boy thing by using used springs and without warning started to backfire through the carb. I rotated the carb so I could access the pilot screw. Have a hi-rise tunnel ram with 2" tall spacers and two 600 Holley 4-bbl carbs on a 350 Chevy crate motor. Engine backfiring through the carb is indicative of a lean mix probably 90% of the time with a valve sticking or out of adjustment 10%. Why does my chevy 350 backfire through the carb? I have a chevy 350 with edelbrock carb and intake manifold, it also has headers. I rotated the carb so I could access the pilot screw. Re: 258 backFIRING through carb I had this when I had a four barrel holley on an old camaro. Now has no power and runs rough. Footage taken from Holley Carburetor Installation & Tuning DVD. Either the Carter or the Holley is far superior (opinion) to the e-clone. from Evansville,WI. Any misconnected or leaking carb vacuum hoses can also encourage backfiring. It idled high but that was it. I've actually had a dist installed 180* off and the engine ran. Backfiring through the carb and the plugs are dark probably from flooding and running rich though. An engine that is running and the carb suddenly runs dry will backfire. When I put the car in drive and get down the road 100' or so, it starts missing, and if I give it a lot of gas it backfires through the carb. I can actually feel it in the throttle linkage and see gasses (not flames) shooting out the carb. 57 HEAP , Apr 25, 2019. Check for proper operation and adjustment of all linkage on the carburetor. This was causing the rough idle. Odds are heat soak is boiling fuel out of carb, so initial crank bowl is WAY low if not empty, as engine cranks pump fills carb and viola, imeadiate restart, no time to boil fuel. Backfires through the exhaust: Screw in mixture screws, decrease squirter size, lower float levels, reset butterflies, decrease main. With the intake, carb and cam, my engine is more efficient, therefore, better on fuel if I don't drive like a kid. Performance Holley carburetors come with a power valve blow-out check valve built in. Over hauled and cleaned the carb. Holley carbs older than 1992, however, may not have this check valve built in. Hello everyone. If they are too big the air speed will be reduced, too small and vice-versa. Water in the engines fuel system will often cause hard starting, low power, backfiring, surging or stalling. 4) Accelerator pump defective or blown out. Re: E350 460 carb backfire: Brad: 5-28-12 : I've got an 84' Tioga Chassis with the 460 and what looks like a 1080 Holley, am buying it for $1800 because the prior owner threw his hands up after 2 carbs. Has anyone used the power valve shield kit ( by Centek) on a holley carb to protect the valve against backfire damage ? I have a 468 BBC dual 750 tunnel setup on the hydro. I replaced the gas and I am able to have it run at a high idle, however when I turn the idle screw down it starts popping in the exhaust. Real backfiring is actually the bike "spitting up" in a sense, backwards through the carburetor or intake. Because of venturi design, when cold these carbs can "freeze" up in the venturi's causing the fuel to puddle. Re: SBC 307 backfires through carb Post by lluciano77 » Sat Dec 28, 2013 6:59 pm lefty o wrote: if its just at initial throttle tip in, very first thing i'd check is that little rubber umbrella seal for the accellerator pump. Q: The carburetor is backfiring and won't hold a cold start fast idle. Carb Tunning. · An exhaust backfire when decelerating, is usually caused by: a lean condition (especially when the throttle blades snap shut) exhaust header gasket leak. I hooked up the hose started it let it run for a while everything was good opened it up a little bit everything was fine shut it down remove the water hose when to start it up again to blow out the water backfire through the carburetor and died when to restart it wouldn't start, tried it again barely got it started sounded. Ding ding the witch is dead. Holley Carb Trouble Shooting. As with most domestically produced carburetors, a 4150 Holley has a choke, float, idle, off-idle, accelerator pump, air bleed, main metering and power-enrichment metering circuits. Carb backfiring on hard acceleration! If you went to a Holley set up properly you would get gains all round especially by optimising the timing. Holley was THE solution maybe because they are the simplest carbs to rebuild and they don't need many adjustments, like the metering rod we find in the Edelbrock. I have gotten the car to idle good but anytime I give it gas quickly it will backfire through the carb and die if I don't immediately let off. Bronco Tech. The car will start to crank but then backfires a fireball through the carb and leaves a small fire burning in the carb. After a hard run, when almost at a stop the engine will occassionally backfire (anyone know why ?). Before rebuild i had no secondaries as they were completly clogged up, every passage. At IDLE, there should not be any more than 5. Check for proper operation and adjustment of all linkage on the carburetor. A lot of times it is caused by the timing being too far advanced. part # 34-3. Update on truck 390. Re: SBC 307 backfires through carb Post by lluciano77 » Sat Dec 28, 2013 6:59 pm lefty o wrote: if its just at initial throttle tip in, very first thing i'd check is that little rubber umbrella seal for the accellerator pump. The next area for fuel control is the carb float needle. and get my mechanic to adjust the timing. Timing is set at 5* with vacuum advance line removed and plugged. Whenever I step on the gas hard, it "hick ups" or back fires up through the carb. Carb of course leaked. Motorcraft 2100 Carburetor Choke Circuit. back fire through carb is a lean cough. 10/4 i'll look into things. If backfiring occurs through the carburetor then adjust the idle mixture screw out another 1/8 turn. Holley makes a coil driver module through which the Terminator ECU can drive the coil (-) without hurting the ECU output. I am thinking that the ignition, which is still being controlled by the Megasquirt, is too noisy and when the RPM's are going haywire that is when it backfires through the intake. chevrolet71. Now back to the list…. Does not occur at low speeds or above 3500 rpm. Well, Holley still makes the List 1850 carburetor, and it's available in 600 cfm versions most everywhere, but they have long dropped the 1-12-X designations. Now this is an all of the sudden problem. How do you know if the power valves are blown ?. Holley was THE solution maybe because they are the simplest carbs to rebuild and they don't need many adjustments, like the metering rod we find in the Edelbrock. I just assumed the previous backfiring was due to the grenaded muffler. You'll find we have some of the lowest prices in the nation. The electric choke. This was causing the rough idle. since i swapped carbs. If you need say, a Holley carb for a Corvette, just enter your vehicle’s year, make, model, and engine up above, and we’ll show you the parts that fit. A carb will backfire under either a lean condition, as in an adjustment, or a malfunctioning accelerator pump. you wont see that and it may ever backfire out. I asked about the way the gas was being ejected to determine if it was a backfire versus stuck float. Can unplug wires to rear four cylinders with little effect on rpm. I have a Holley Street Dominator intake manifold. Hi, this carburetor in question is on 1987 plymouth voyager caravan 2. · We get a backfire through the carb if you open the throttle quicklyIf you don't have a late-model Holley w/backfire check-valve, install one. maybe ya got the timin wrong. 2100 Identification. In order to truly tune my carb, I want a better understanding of the symptoms of lean vs the symptoms of rich. Use your carburetor repair kit to identify replaceable welch plugs. I have rebuilt and jetted the carb aslo tryed fattening her up thinking it was a lean condition. 7 seems to be backfiring through the (Holley) carb but only under load. Each Holley carburetor has a specific rebuild kit for its number. A Holley carburetor is made with four basic parts, the throttle plate, main body, metering block and float bowl assemblies. Some carbs have it some don't. Replace the powervalve with the same size. From my experience, one problem with power valves is that they can rupture from a carburetor backfire. You may have to register before you can post: click the register link above to proceed. It idled high but that was it. Re: 258 backFIRING through carb I had this when I had a four barrel holley on an old camaro. The fault is similar to the one shown by a carburetor with a faulty accelerator pump. Do not overtighten or put the casting in a bind, as these flanges also break easily. I replaced the gas and I am able to have it run at a high idle, however when I turn the idle screw down it starts popping in the exhaust. Now has no power and runs rough. Less than 30k on the engine. Do not depend on the factory delivered settings. POOR RUNNING QUALITY DOES NOT MEAN A DEFECT IN THE CARBURETOR. The 460 in our motorhome [87 FORD E 350 chassis] backfires thru the carb when it's in a hard pull. I've gone through and corrected them, but now I'm having odd backfire through a brand new Holley 2bbl carburetor. While this carb is clearly in need of a rebuild and thorough cleaning, we grabbed it to detail the process modifying for draw-through applications. A faulty ignition system is a possible cause of a engine backfire. #21 Backfiring On Deceleration: Hello Group, One of the most asked questions pertaing to the Honda Elite CH 150/250 and CN 250 Helix involves a backfire through the exhaust on sudden deceleration. The Operation of THE GASOLINE VAPOR MAKER. The fuel had water in it. After that the motor sounded stronger at idle but when I would give it gas it would bog and hesitate. If backfiring occurs through the carburetor then adjust the idle mixture screw out another 1/8 turn. Hello everyone. Only mods to the 4160 carb was the 4. Notice that my Holley doesn't have a spring on the vaccum secondary diaphragm, I don't know why. Replaced distributor cap, plugs, wires, and reoriented them to the correct location. So last week was the first time with the boat in the water, no problems, ran great. summitracing. Q: The carburetor is backfiring and won't hold a cold start fast idle. We usually refer to an exhaust backfire as a "backfire", and backfiring through the carb as "spitting" or "coughing". Crazy valves were hangin open. In 1967, Chrysler used both Carter and Holley carbs on their 440's. 5 stock with a 650cfm double pumper Holley carb. I am getting an occasional backfire through the carb on acceleration. Our secret to success is that every carburetor that we sell is tested on a live running engine before it leaves our shop. Troubleshooting - backfire through carburetor. I asked about the way the gas was being ejected to determine if it was a backfire versus stuck float. Basically what it says. The carb is a brand new holley 600 4 barrel. After a hard run, when almost at a stop the engine will occassionally backfire (anyone know why ?). You don’t want to damaged the mixture screw just below the plug. Steve (ff33rod) here up in the Vancouver area on the West Coast of Canada. The Holley type accelerator pump system consists of three main components: the pump diaphragm, the pump cam, and the pump nozzle (a. During cranking, sometimes get a very loud pop (backfire) through the carbs (enough of a "pop" to blow off a plastic vacuum cap on a carb). 2) Test it using the idle mixture screws. All three carbs did the same thing. The fault is similar to the one shown by a carburetor with a faulty accelerator pump. this weeks issue; 5. There's a large manifold vacuum port on the rear of this carb, and when that one gets loose the rpms go higher. Backfiring is typically a too-rich condition. Timing is set at 5* with vacuum advance line removed and plugged. Re: Why am I getting a backfire through Carb on hot start ianxy351 on October 5th 2012, 4:01 am If you got a big-ish backfire thru the carb then it may be worth checking your powervalves. And I thought that was my problem as well, but turned it really was just a small exhaust leak. I've had bad carburetor gaskets act exactly like that. Re: 258 backFIRING through carb I had this when I had a four barrel holley on an old camaro. Aftermarket Holley carb numerical listing by carb number Holley HP series carb specs by carb number Holley's accelerator pump instructions are on pages 6 and 7; Holley instruction manuals by part number; Manual, Exploded View and Nomenclaturefor Holley models 2010, 2300, 4010, 4011, 4150, 4160, 4165, 4175, and 4500 Holley technical library. 0 longblock Victor Jr. I have also tried a various ranges of timing. Timing dial in, big bump in jetting, vacuum secondaries and floats set correctly, and acc pump shot increase and she's starting to run like a raped ape. The only way to fix it is to replace it. I bought my boat last year and was never able to get the boat over 30mph which is when it would backfire through the carb. How do you know if the power valves are blown ?. just my thoughts. I don't know much about quads, but was reading that there is a passage that feeds fuel to cover a hole when the secondary flap opens. The 750 3310. This condition is generally caused by the incorrect fitting of after-market accessories such as exhaust systems, air filter systems, or replacement carburetors of a different type or size. Now back to the list…. I also pulled the plug and it was really black. 0 psi; if the vehicle has an adjustable fuel. I checked fuel flow from the pump before putting the line back on and filled up a 16oz bottle in a few seconds. Why does my engine spit or backfire? First off, you need to determine whether it is backfiring out the exhaust or back up through the carb. The fault is similar to the one shown by a carburetor with a faulty accelerator pump. Since I first put the carburetor on it started 2 times with no problem. if its good it should pull. Troubleshooting - backfire through carburetor. The kits for this carb are expensive because Holley doesn't sell very many. · holley carb backfires threwWell black plugs would mean rich but popping through the carb usualviolent lurching from Edelbrock carb after backfire. Removed those, reassembled carb, installed and road tested. the motor backfires or pops, increase the gasoline supply very slightly. One more thing. Re: Backfire through Carburator at high RPM I cleaned the carb and it was in perfect shape, compressed air and blew it all out. my thoughts are the intake valves are not seating fully but a shop just installed a new head less than 600 miles ago. 75 Stars and stripes with ford 302 4 barrel holley started popping through carb, and loss of power during acceleration. The one barrel carb on the 6 cylinder engine on my Edsel keeps backfiring unless I pull out the manual choke a little. Is this the way the carburetor is designed or is there a problem? Does anyone have a solution?. Consider a low restriction air filter element if you have the correct housing. you fix it.