Backfire through exhaust first, now through carburetor too

Good morning,

Backfire in the exhaust usually come from a timing issue. If the timing is retarded from the factory spec, it will backfire out the exhaust.

Do you have an air pump on the engine?

Roy

I've double checked timing, no air pump. I'm pulling thermostat today, to check restrict-or. thanks

Engine Performance problem
1983 Ford F150 6 cyl Four Wheel Drive Manual

I have suddenly had a backfiring problem, and it is stumping me, as it seems to only happen when I am turning. The problem is twice as bad when turning left, but have noticed the occasional miss when driving straight

When the last time you had it tuned-up? Check the sparkplug wires if its leaking and also the distributor cap.A/F mixture could be too lean or rich, Air injection diverter valve and the lis tgoes on.

just started suddenly, but what would make it happen primarily when turning?

but what would make it happen primarily when turning?

Honestly I've never heard of such problem-I will check the sparkplug wires they move around when not secured properly and could be leaking into one another

I figured this one out last night, I had a partial break in the coil power wire, and the retainer for the wire had broken, letting it swing back and forth while turning. this momentarily broke the connection, letting gas build up in the cylendars and exhaust until it fired again, then BOOM!!! Fixed the wire, and replaced the coil connections also, seems to run fine now!!
THANKS FOR THE HELP!!!

Engine backfiring through intake after it gets hot fuel pressure was low put on new fuel pump and fuel filter fuel pressure back to normal now still has the same problem

Backfiring through the intake is usually a timing problem. Make sure the timing is set to spec and that the timing chain is in good condition.

But if it was that would it not do it all the time only does it while cruzing not idleing or while youre getting on it hard

Maybe. Cruising puts the least strain on the engine and lets the timing chain bounce. It could be happening at idle too, just not badly enough to hear it. The timing could be currently set so that the problem only shows up while cruising, advance taking up the slack at idle and under load.

Hears the deal; this all started when i changed the spark plugs. truck ran fine i was just doing pms. changing the plugs ended up with having to rethread one of the coil pack bolt holes in the intake. one that was repaired i installed new upper and lower intake gaskets, torqured everything to specs, installed 2 new coil packs (broke 2 getting them out), replaced all 8 plugs with ngk oem replacements, buttoned everything up and to my suprise this lopeing and sounds like intake backfiring. please help!!!! engine is a tritron 4.6

Go to this link: https://www.2carpros.com/articles/engine-backfires-while-running

checked fuel pressure at rail 40 psi

if this helps rpm goes from 700 to 1500 radically.

Check for vacuum leak and clean the idle air control valve and see what happens

occasionally, some days more than others it sputters, I'll have to play with the gas pedal to get up a hill or to take off, backfires once in awhile, seems to be more in the afternoon than morning, some days does good, other days real bad

have added fuel injection cleaner

Has the check engine light come on? Have you checked fuel pump pressure?

okay still no change, i took the 4 spark plugs on the rightside out and they are sooted and dry. should i check the injectors, seems like it is not getting fuel to the cylinders...not sure

[quote:8a248b4d3e="Jacobandnickolas"]Has the check engine light come on? Have you checked fuel pump pressure?[/quote:8a248b4d3e]

the check enghine light hbas been on for 2 years, before this latest action. A mechanic the other day did a quick diagnostic, said something about a temperature reading being off, some code indicated that, needed more diagnostic too tell specefics.

lower intake gasket, replaced and runs as expected. Vacuum issue solved. thanks!

He may be talking about the temp switch. It tells the computer how rich or lean to make the fuel mixture. That could be the issue.

Or pleasure. Happy to help.

Closing thread.

2000 Ford F-150 4.2L V-6 2WD MT, truck hesitates and backfires when under medium- hard acceleration in 3rd, 4th and 5th gears, does not hesitate or backfire under easy acceleration/ light load, no check engine light, idles smooth, accelerates smooth under normal conditions, replaced air cleaner, fuel filter, plugs and wires, and pcv valve so far, still no luck, any ideas?

Your probable causes could be one of the following:

Oygen sensor
Dirty fuel injectors (cleaning the injectors often fixes this).
Bad MAP (manifold absolute pressure) sensor
Bad TPS (throttle position) sensor
Bad or dirty MAF (mass airflow) sensor
Low fuel pressure (leaky fuel pressure regulator or weak fuel pump)
Vacuum leaks (intake manifold, vacuum hoses, throttle body, EGR valve)
Bad gasoline (fuel contaminated with water or too much alcohol)


Sometimes, what feels like a hesitation is actually ignition misfire rather than lean misfire. The causes of ignition misfire may include:

Dirty or worn spark plugs
Bad plug wires
Weak ignition coil
Wet plug wires

my truck is backfiring thru the intake under a load i have checked the compression the lowest cyl. is 130 psi and the highest is 145 psi, fuel pressure is 45, i replaced the plugs,wires,ign.module and the pickup in the dist. also the tps. checked the timing right on at 10 deg. had the valve covers of and it appears all rockers are moving the same distance( though maybe a flat lobe on the cam) i need help could this be a flat lobe? dished lifter? timing chain? it smells like it is running a little rich. i have also scanned for codes and the only code is no knock sensed but i cant find a knock sensor, it did sit for a while before i purchased it and it had some bad gas although i have added about 10 gallons of good gas

Most causes of backfires in the exhaust system can be addressed by troubleshooting the reason for the air to fuel ratio imbalance. The solution usually involves checking for vacuum leaks, changing the airflow sensor, oxygen sensor, or fuel filter to ensure the fuel system is functioning properly.

A common backfire situation occurs when there is a small leak in the air injection system that feeds the exhaust system. This can cause unburned fuel to explode suddenly. One of the most common causes is a stuck or faulty air intake or gulp valve near the exhaust manifold.

Backfiring can also occur with a sudden drop in fuel pressure. This may be due to a faulty fuel pump or a plugged fuel filter. Correcting problems in the fuel system usually resolves these issues.

Incorrect ignition timing to the spark plugs is another cause of backfire. Adjusting the ignition distributor, if the engine is so equipped, may resolve this problem. Adjusting engine timing is not difficult and can be done with a timing light by following the timing adjustment procedure for your car. If you do not know your car's ignition timing procedure please visit our car repair manual page. A vehicle that is not timed properly will not idle, run or operate correctly and will often backfire rapidly. On newer cars you will need to scan the pcm to check for CKS (crankshaft angle sensor) and CMS (camshaft position sensor) related trouble codes.

The 5l engine idles rough when warm but the big problem is backfire at mid speed with slight exceleration. That will light the check engine light. It will run at full throttle. I have installed platinum plugs, wires, cap & rotor and oxygin sensor. Also cleaned the mass air flow sensor and egr. Help

Inspect and test the following:

Dirty fuel injectors (cleaning the injectors often fixes this).
Bad MAP (manifold absolute pressure) sensor
Bad TPS (throttle position) sensor
Bad or dirty MAF (mass airflow) sensor
Low fuel pressure (leaky fuel pressure regulator or weak fuel pump)
Vacuum leaks (intake manifold, vacuum hoses, throttle body, EGR valve)
Bad gasoline (fuel contaminated with water or too much alcohol)

Sometimes, what feels like a hesitation is actually ignition misfire rather than lean misfire. The causes of ignition misfire may include:

Dirty or worn spark plugs
Bad plug wires
Weak ignition coil
Wet plug wires

update on backfire issue. replaced plug wires, plugs, readjusted float level, seems to be much better. still has a issue of lean misfire @ low RPM

It sounds like you may have a weak fuel injector, can you remove the spark plugs to check the color of each? You are looking for the one that looks different that will be the cylinder that is having as issue here is a guide to help.

https://www.2carpros.com/articles/how-to-test-a-fuel-injector

Please run down this guide and report back.