Troubleshooting - backfire through carburetor

Footage taken from Holley Carburetor Installation & Tuning DVD

[@feeneysmechanical6215]

Another reason for a back fire through the carb. Is plug wires that weren't installed correctly on the correct cylinders. Also a oil pump that locks up a little and twists the drive rod from the distributor will cause a backfire

[@geddon81]

My truck just got converted from EFI to carb, have a holley 4bbl on it. WHen I got it back she had some trouble spots here and there, over time of driving it I decided it was time I take a shot and tune the damned thing myself lol. Well I did it, started from zero and tuned the carb until she felt smooth and no popping or hesitation could be felt . After awhile I finally got it, or so I thought. She was riding beautifully , the 454 its attached too running calm and steady. Then all the sudden tonight while giving it a bit more gas than usual a massive pop and a good plume of smoke made its way out from under the hood. For 2 days she never had an issue, then tonight I thought I blew the damned thing off the intake lol. Pulled over and popped the hood to make sure there wasnt a fire or anything and nothing, just spit a big flame and she was back to being smooth . Before I re-tuned I can tell you she was definitely running a good bit rich so I made sure and kept it a bit leaner than where the installer had it. Now I dont know if I need to go more rich or even more lean lol. Find out tomorrow I guess .

[@charleshorseman55]

Whelp, how did it go?

[@kekistanimememan170]

Should have stuck to EFI

[@Good-Enuff-Garage]

so pretty much check everything, ha ha, great got it

[@kaloosh2639]

😂

[@Dubtee]

Holley makes the most useless videos.

[@1badombre82]

Lol did that twice already. What next?

[@johngranato2673]

...and if you have power brakes, make sure your booster is not damaged and creating a vacuum leak. Disconnect and plug the booster to intake hose if any doubts.

[@pigeonsil240sx]

whats the theory behind it though? for example if you have bad plug wire how does it even fire in that cylinder? i understand how bad timing could cause this but i dont understand how this would accure if timings fine? the fuel sprays as intake valve opens,the piston goes down to draw in air and as it comes up the valves close and combustion accurs so if cars timed correct how is faulty plugs/wires/fuel create the backfire?

[@zainulabideenzain3]

Upon wide open throttle, my car intermittently gives severe jerks/misfire. This started happening after rebuild. What could be causing the issue? Can the large jet cause this problem?

[@HolleyPerformance]

There are a number of factors that can cause this. Did it do it before the rebuild? If not, then I would check things like ignition timing! Also check fuel pressure, then look into carb jetting and accelerator pump operation and settings. Thx J

[@zainulabideenzain3]

@@HolleyPerformance It did not do that before the rebuild. I replaced the whole carburetor with a new one, and problem solved.

[@HolleyPerformance]

@@zainulabideenzain3 I would have to guess then that something was installed or assembled incorrectly when the rebuild was done. Glad you figured it out. Thx J

[@lpcal8863]

I have a 1990 Dakota sport (3.9 V6) and they use a Holley EFI carb. I’ve had stalling and tough idle issues but yesterday I had a backfire. I immediately replaced the ignition coil, plugs wires, and spark plugs, as well as cleaned the EGR valve. What else could I do before I have to take it to the shop and have them check the more complex stuff?

[@gagehowell3566]

Thank you so much, a few of these I knew but a few I didnt!

[@charleshorseman55]

Had a quadrajet on the 360 ramcharger, ran like ass after a rebuild, put a holley on, backfires every 1/2 second out of the carb. Checked the electronic choke, wire wasn't connected. Connected the wire, now it backfires every 1/2 second LOUDLY lmao. Send help.

[@equittone1839]

Sorry for my bad english, my carbs just blipping when the engine is cold (if i rev it) when the engine already hot it runs normally, is it jetting problem or do you know the problem? 🙏

[@gtzglvez]

Check distributor cap to see if its craked in any way along with ignition rotor..

[@THE.PUNISHER93]

thank you so much

[@richardmckibben2384]

Sounds good 👍

[@jessewhite34081]

Forgot to mention improperly adjusted carburetor will do the same thing edelbrock 1406 is really bad about this

[@78ramcharger53]

I'm having problems with mine right now.

[@whodatisful]

That narrows it down

[@nicks.carter574]

DISTRIBUTOR MAGNET OR SPUR ALSO !

[@avocatsyria]

Is this fire dangers, i mean is there any chance to fier all my car 😢?

[@mclarpet]

I'm on fire, I'm on fire, I'm on fire......

[@HolleyPerformance]

Funny!, but not Funny if it has happened to you! :O

[@mclarpet]

To be sure. We were told about never looking down an operating carb when we started dynamometer at a uni.

[@slapkickinmule]

@@HolleyPerformance Hi, so, I normally work with computer controlled fuel injected stuff or diesels, but I got a motorhome with a 454 big block, and it was leaking gas, burning very rich, and eventually one of the back fires ignited the gas that was all over the engine block crisping and shorting all the wiring as well as melting the vaccum hosing, the components between vacuum and electrical lines seem fine, but I'm not sure where to start after cleaning off all the fire extinguisher dust

[@HolleyPerformance]

@@slapkickinmule I'd remove the carb from the engine and try cleaning it up good with some carb cleaner and a brush. Then disassemble it and try to determine and correct the leaking issue. Thx J

[@user-jq3wn6kr2n]

Please i have a superban 92 engine 454 that works two hours and then stops suddenly and a fire occurs from tbi And I replaced all the sensors and everything and I couldn't find a solution

[@bradking2113]

I have a 450 slayer quick fuel carb that does that all the time idles beautiful but as you give it a quick boot it backfires up through the carb its just a piece of junk,waste of money that was, put the holley on no problems at all

[@jadenrhines234]

Mine does fine until it’s over 1/2 throttle, then it bogs down and eventually will come out of it. It also gets better as it warms up more. That means it’s too lean right?

[@HolleyPerformance]

It could be too lean or too rich! Does it pop back through the exhaust or air cleaner? Does it do it when you roll into the throttle or just when you punch it? Best thing is to pull and read the spark plugs. If it eventually comes out of it I would say the main jetting is fairly close and maybe look at other areas (squirters, power valve, etc). You also need to check your timing and make sure that the mechanical and vacuum advance in your distributor is working properly, as well as all the other ignition components! Thx J

[@jadenrhines234]

HolleyPerformance thanks for the help!

[@YayArea4155]

@holley my skylark is having the same issue but it back fires trough the carbuator only when i snap tue throttle .

[@crack3273]

Can you remember how you fixed it? My car is doing the same exact thing. I've changed spark plugs, cleaned the carb and checked the vacuum advance.

[@YayArea4155]

@@crack3273 just fixed the issue it ended up beign the cam shaft replace camshaft and lifters issue resolve.

[@freddiebryant8932]

agree

[@drakesairguns7848]

well... i have everything on the problems list...

[@ProxyofMalice]

E e dd dv

[@cfazekas0441]

I just built a single silinder race motor and it backfires through the carb all the time

[@mk6744-]

Little bit late but your timing is Off bro

[@samsquires2877]

How to fix this problem convert it to EFI.

[@TheWolverine-rm2kr]

Efi doesn't fix the bad timing chain, cam, timing off, or bad distributor

[@elroyslater8461]

What about wires being mismatched

[@apriljones8479]

yes

[@richk.4020]

then your motor would be missing, you would know that!

[@brooklyncarsandcoffeehealt4329]

Will a bad power Valve can also backfire?

[@HolleyPerformance]

When does your backfire occur?? (ex. Idle, hard acceleration, WOT, constant cruising speeds, deacceleration)?? A blown Power Valve acts like it is open all the time resulting in a dramatically over rich fuel mixture at idle and no response when trying to lean out the Air Screws. The most common cause of a backfire is ignition related, possible causes could be that the timing is off, too much or too little mechanical/vacuum advancement, or possibly a bad cap, plug or plug wire. Thx J

[@crystalwynia2352]

@@HolleyPerformance We have a 454 mercruiser 7.4 liter in our boat, carb has been rebuilt, new mechanical fuel pump,new distributor cap, new plugs and wires but we are still having backfiring when we are at WOT then we slow down and the backfiring continues at lower rpms as well. It doesn't start off backfiring at low rpms only after we got up around to 3 to 4k rpms. Any idea? I'm thinking timing issue...

[@66mustangdriver1]

your ignition timing is off.

[@MrKIKO714]

I have this problem whit my carburetor, how i can turn on the ignition timing

[@carlosspears4637]

When I crank my 98 grand marquis up, the carburetor backfires, but when I plug the number 7 plug wire off it stops.. can someone help me

[@carlosspears4637]

When I unplug the number 7 wire it stops,, sorry

[@ll6946]

Bad spark plug?

[@firstname1380]

Think you forgot if your car is smashed and if the engine isn’t in the car all the way

[@dirtbikeboy8169]

Mine runs and ideals fine , until I rev it , it back fires out of carb

[@HolleyPerformance]

You may need a larger accelerator pump nozzle, or it's possibly your accelerator pump linkage has too much slack in it.

[@ton-locc8069]

Did you solve the problem if so how?

[@ted850760]

@cfazekas0441 What is a silinder????

[@h10hunter]

Its like an appendix. Your engine doesnt need it.