Why does my Chevy 350 backfire when I let off the gas?

If it backfires when you let off the gas peddle it has air getting into the exhaust, either an exhaust gasket or cracked manifold before the catalytic converter or the emission control’s Air Injection system. The air injection check valves (STANDARD MOTOR PRODUCTS PT#AV7) are common failure parts.

How does the ignition work on a Chevy 350?

The engine’s ignition system is triggered by an electronic driver which signals the ignition coil when to fire. By design the resistance it takes to fire the coil via the spark plug is figured into the system.

What causes a Chevy C / K to stop running?

A leaky fuel pump will drain the line up to the carb, but about 15 seconds of cranking will fill the line again. 2. A sticking mechanical choke or a bad electric choke. Try; when you return to your truck from the Quicky Mart, put the accelerator slowly all the way to the floor, let your foot up slowly and then crank the engine.

Why does my Chevy k1500 stall when gas is released?

I have been working on our 89 Chevy K1500 and am still having an idle issue. The truck idle drops and lopes and occasionally completely stalls. This usually happens when driving slow in town… backing out of parking space, letting off gas when coming to a stop sign or to park etc. It does fine to start and accelerate.

What should the fuel pressure be on a Chevy Cheyenne?

93 Chevy Cheyenne k3500, if it is running the Chevy vortec engine the fuel pump pressure is way too low, should be 56 psi+ depending on CSFI/CPI system or it will not start or open injectors, with out the aid of starting fluid. The factory manual specifies that the fuel pressure for the CSFI system should be between 56-62 PSI.

Is there no fuel from injectors to start truck?

No fuel from injectors to start truck. When I try and start my 93 Chevy Cheyenne k3500 no fuel come out of the injectors. If I use starting fluid the truck starts and the injectors work great. Has died a couple times while driving, but mostly runs fine and then won’t start one turned off.

Why does my 350 Chevy truck not start?

350 chevy truck cranks but won’t start – Maintenance/Repairs – Car Talk Community Truck ran fine with no indication of problem. When outside temp. dropped in teens one morning it wouldn't start.

Why does my car shut off when I step on the gas?

Power loss, especially on acceleration, may be the first sign. As flow continues to be impeded, the fuel filter may ultimately lead to a no-start condition, as fuel can no longer get to the engine. Vacuum leaks: The engine of a car is basically a large air pump. Air is drawn into the cylinders and mixes with fuel that is compressed and ignited.

How does the carburetor work on a Chevy 350?

The carburetor delivers the air/fuel mixture to the engine, and the distributor ignites that mixture within the cylinders. Thankfully, because both of these components are on top of Chevrolet’s 350 small-block engine, checking them is quite easy.

What causes a backfiring exhaust on a Chevy 350?

Thankfully, because both of these components are on top of Chevrolet’s 350 small-block engine, checking them is quite easy. Backfiring is typically caused by an air/fuel mixture that is too lean, meaning the mixture has too much oxygen in it.

What causes a choke on a 350 cubic engine?

If the carburetor is adjusted properly and the choke is functioning, the problem may stem from the distributor. Underneath the 350’s distributor cap are nine metal contacts. One contact is for the coil wire, and the remaining eight are for the 350’s eight cylinders.

What to do with a 350 cubic engine?

Most of the carburetors installed on the 350 use a single air/fuel mixture screw, while some carburetors use two. The general rule of thumb is to tighten the adjustment screw (s) into the carburetor with a screwdriver while the engine is idling until the engine speed starts to increase, then loosen the screw (s) half a turn.

How to order a Chevy crate engine for free?

Crate Engine, Long Block, Small Block Chevy, 350, Dressed, Each Part Number: MLL-BP3501CTC1 More Detail… Order this item and get free shipping and handling on this item! Truck freight fees also waived on this item. Applicable shipping fees will be charged, if required, on additional items added to the order.

Why does my car make a popping sound when it backfires?

A rhythmic popping sound which is not as prominent as lean under power backfires. The problem list below will give you an idea of what causes could be generating this condition. The engine’s ignition system is triggered by an electronic driver which signals the ignition coil when to fire.

What causes a car engine to backfire when under load?

This detection is done by looking for a flat back shoot which is evidence of a leak. On engines made from about 2001 and older are equipped with a air injection system that is fed into the exhaust system when the engine is under load. This is to burn unspent fuel which helps the emission system work better.

Why do I hear a bang when my engine backfires?

First and the most common way is when the engine is running a small explosion of un-burnt fuel is ignited inside of the intake manifold creating a loud bang which is the backfire sound you hear. This explosion can bend the throttle actuator plate, push intake gaskets outward creating a vacuum leak and even blown apart a plastic intake manifold.

What causes a backfire on an unburned engine?

Unburned fuel then is allowed to pass into the exhaust system where it can backfire. The same type of problem can be caused by a worn out or damaged spark plug wire. A bad wire will make the spark’s travel difficult, weaken the spark, or simply push it into an adjacent wire or to ground, resulting in a backfire.

Can a bad sensor cause an engine to backfire?

An engine sensor malfunction can also lead to backfires. Take for example a bad mass air flow (MAF) sensor. The engine computer uses this and other sensors to compute the amount of fuel to inject into the engine according to operating conditions.

What causes a fuel intake back fire explosion?

An intake back-fire explosion can be caused by the fuel air mixture being to lean when the engine is demanding power. Every internal combustion engine runs on a mixture of 14 to 1 which is fourteen parts air to one part fuel. Proper fuel pressure is needed to atomize the fuel correctly when it leaves the fuel injector to complete the burn process.

Why are my GM 454 backfires breaking down?

If you see any white stains around the ground bracket, the coil is breaking down due to being over worked ( too long at max voltage). Another thing to check is fuel pressure. The system is already a low pressure system to start with. Unfortunately you have to tee into the pressure feed line to get this info.

Why does my Chevy 350 Backfire at high RPM?

The 90 degree elbow in the PCV Valve hose at the base of the throttle body to the PCV valve is common to either fall off or have a hole in it. Most of the time the engine will idle at a higher RPM a suction sound can be heard.

Why does my truck sputter and backfire when I accelerate?

Hey I’m new here and desperate for answers! I’m in the middle of PCSing with the Air Force to Japan and was getting my truck ready to sell, when it started acting up when I accelerated after right after starting the engine. een The engine starts and runs fine, when I leave for or from work.

What causes an intake back fire in a car?

If the check engine or service engine soon light in on scan the computer for trouble codes. This will help locate the system that is having a problem and needs repair. An intake back-fire explosion can be caused by the fuel air mixture being to lean when the engine is demanding power.

How to check for fuel leaks in a GM 4.3L?

Once the fuel pressure gauge registers pressure, check for fuel leaks around the Schrader valve. It’s very important that NO fuel leaks are present for the accuracy of the test. Once you have verified no fuel leaks, continue to the next step. Have your assistant crank the engine as you eyeball the fuel pressure gauge.

Why does my Truck start and run then dies?

59 people found this helpful. Something grounded out and prob shorted a inline fuse so when you turn the key to run you hear your fuel pump Prime the line but when you crank the motor starts then dies. It has to do with your gin. Or ecu. Pcm not telling the pump to fun.

Why is the crank sensor on my GM Truck not working?

Crank sensor is getting power and 50 psi with key in the on position (not running). Any ideas? Also, attempted the reset for the passlock system and took negative battery cable off to reset computer. I have one word STOP. Put some time into diagnosing the problem you’ll save time and money.

How often does a GMC Yukon engine die?

Engine cranks, briefly… Engine cranks, briefly starts and then dies. The engine cranks over, the engine will start and within one second the engine dies. This occurs once every other month. Took it to dealer for a major tune up and it still happens.

Why does my GMC Yukon engine start and then shut off?

Pressed it down and good pressure of fuel came out. I know it’s firing because it ran when I sprinkled fuel down the intake. On it’s own, it will start for a sec and then shut off. Something won’t allow the injectors to continue to pulse for some reason.

What happens when the PCM turns off the fuel pump?

When it doesn’t receive the right password, it disables the fuel pump. When the key is turned to on, the fuel pump comes on to prime the system, so it will run for a couple of seconds, but then the PCM will turn the pump off if all is not well immediately after start.

Why does my Chev k1500 350 Vortec backfire?

When I hear backfiring, can only think about ignition problems, with rich fuel problems and good ignition, shouldn’t backfire, but will see black smoke from the exhaust. With erratic ignition, if the spark does come, can come at any time, even the wrong time, and if the intake valve is opened, it will backfire.

What causes a 350 to backfire at 800 rpm?

The backfire is through the exhaust not the carb and happen when the throttle is opened up from idle (roughy 800 rpms) This started to happen after I changed the plugs, plug wires and removed the header to get the plugs. Any ideas on how to fix it would be great! Thanks.

Why does my Chev 350 Vortec not start?

Cold air is dense and spark goes through it harder. Give big ass GM gaps spark plugs and bingo, all secondary spark is crap. Guy came back today with his truck. Busted a brake hose, but he says gas mileage got better since tune-up and injector cleaning. Gas filter was done at tune-up also.

What causes a car engine to backfire with low gas mileage?

On older engine’s ignition timing is set at a specific degree in relationship to the crankshaft. If this timing is mis-adjusted it can cause low power, poor gas mileage, engine detonation (pinging) and backfiring through the intake or exhaust system.

What causes an exhaust tail pipe to backfire?

An exhaust tail pipe backfire is caused by an excessive amount of un-burnt fuel remaining in the exhaust system or fresh air being allowed to enter the system which ignites a small amount of un-burnt fuel. If fresh air is allowed to leak into the exhaust system it will ignite the un-burnt fuel inside the system creating a popping noise.

Why is my Chevy S10 engine stalling out?

This can be caused by the fuel pump or fuel filter. If your Chevy S10’s engine timing is off, it’s going to stall out, misfire, and altogether not run properly. Here are some of the more common causes of an engine timing problem: VVT Problem – Many modern engines are equipped with Variable Valve Timing.

What causes a backfiring exhaust on a 350 cubic engine?

Why does my Chevy truck backfire when I hit the gas?

Its sputtering, backfiring, misfiring, in the low RPM band (below 2k) hit the gas and it upshifts and clears up. I also noticed its idleing rough. So, leaky-cracked manifold?

Why does my Chevy 350 backfire when I accelerate?

If you hear a pop sound under the hood when you accelerate it is most likely running lean (Not enough fuel) from either a vacuum leak or the fuel pump failing (low fuel pressure). The 90 degree elbow in the PCV Valve hose at the base of the throttle body to the PCV valve is common to either fall off or have a hole in it.

What causes a car engine to backfire at idle?

Using a smoke machine or carburetor cleaner you can check for a vacuum leak and repair it to fix the problem. A repetitive backfires are generated when the engine is simply running at idle or at cruising speed and can be inline with the engine RPM. A rhythmic popping sound which is not as prominent as lean under power backfires.

What are the symptoms of a bad intake manifold gasket?

Symptoms of a Bad Intake Manifold Gasket – Chevy 4.3L 1 Engine misfires 2 Sluggish acceleration, lack of power 3 Lean or rich air to fuel ratios 4 Engine overheating 5 Low coolant light illuminating 6 Leaking coolant / dripping onto garage floor More …

Why does my check engine light not come on?

When this resistance becomes excessive due to severely worn spark plugs or a bad ignition coil it can cause these drivers to malfunction at which point they can crossfire into an opposing cylinder either under power or at idle. This condition may or may not be detected by the computer so the check engine warning light may not come on.

Why is my GMC Sierra 1500 stalling out?

Checked it, cleaned it off, verfied that contact wanhers are all steel and attract a magnet, reinstall the ground wire. No change. Next, read somewhere that Engine Coolant Temp Sensor if malfunctioning could cause the ECM to think the engine is at -40 deg F in dflt mode.

What causes a car engine to crossfire at idle?

By design the resistance it takes to fire the coil via the spark plug is figured into the system. When this resistance becomes excessive due to severely worn spark plugs or a bad ignition coil it can cause these drivers to malfunction at which point they can crossfire into an opposing cylinder either under power or at idle.

Why does my car run rough at idle?

That is to say combustion may be disrupted. You will feel, and maybe hear, this as a brief stutter in the engine. You might feel that the engine runs rough or vibrates at idle, say, when you’re sitting at a red light. This is similar to the above in that it stems from poor spark timing.

Why does my GMC Sierra suddenly stop running?

Truck suddenly stops running, acting like it’s out of fuel. There is fuel in the gas tank and, I can hear the fuel pump when I turn the ignition on. Is there a fuse, or relay that is maybe causing this to happen?

Why is the Check Engine light not coming on?

Even if the check engine light hasn’t come on, you may find a pending code that can guide you in your diagnosis. False input or lack of input from sensors like the crankshaft position sensor (CKP) or camshaft position sensor (CPS) can prevent the engine from starting.

Why does my car not start when I Turn on the ignition?

The most common causes are in the ignition (for example, a bad ignition coil) or fuel system (for example, a clogged fuel filter). However, the source may also be a mechanical fault (for example, a leaking valve), or faulty components in other systems.

Why does my Chevy 350 backfire when I let off the gas?