What can cause a car to catch fire?

Sorry if this is the wrong forum. Mods, please move as needed.

Yesterday as I was driving down the main street in my town, I noticed that one of the cars ahead of me in the right lane had flames coming from the rear (underside). The driver wasn’t aware of this happening until the occupant in front of me had rolled down his window and yelled to her that her car was on fire. She quickly turned off onto a side street, and I lost sight of her. I would have stopped to help, but honestly I have no idea what to do in those situations, I didn’t have my cell phone on me, and there were businesses nearby so she could get help. Plus, I didn’t want to be close if her car had exploded (I’m sure that’s just a movie phenomenon, though).

But I got to wondering: Why was her car on fire? What are the correct steps to take in such a weird situation? Aren’t fuel tanks appropriately designed to prevent a major catastrophe if the car happens to be flaming?

I once watch a whole car burn to nothing but a charred skeleton in a parking lot. I was parked across the street and a few buildings down, and witnessed the tires blow out before the fire department arrived and hosed the thing down. Needless to say, the car didn’t explode like in the movies, but it was entirely engulfed. I was fascinated.

heat or electricals, basically. There’s 12v electrics running all throughout your car and your engine and exhaust get pretty hot too. Either of these things can cause a fire. If it was coming from the rear could be the exhaust heat wsa causing something to smoke or to catch.


I would bet that 99% of car fires are started from electrical problems.

However, I saw one that wasn’t. I was following a pick-up truck when it started to smoke underneath the bed. By the time I got the guy to stop, there where flames. Apparently, some newspaper blew up and the exhaust system set it on fire, which in turn set the spare tire on fire.

I would suspect gasoline leakage from the fuel filler hose, the fuel line going from the tank to the engine, or the tank itself, most likely ignited by hot exhaust.

But what should you do if this happens to your car? I have to admit, I would be scared silly if I were that lady.

Also: I’m sure this is a rare occurance, otherwise I’d have seen it more often. Would the blame be faulty wiring? Is there anything you can do to make sure it doesn’t happen?

If it was a gas leak, wouldn’t you be able to smell gas?

In addition to the answers given, there is one sharing common ground with being a frequent source of ignition at home: careless smoking. We’ve responded more than once for a butt flicked out the front window which re-entered another window further back and ignited the interior. One other oddball is ignition of trunk contents which then spreads to the vehicle.

If you have an extinguisher, and know how to use it, go ahead. Otherwise, get yourself and everybody else well away from the vehicle and call 911. Cars release a ton of toxic fumes when they burn, and many things can be hurled a distance away from a car fire. (Energy absorbing bumper mounts, gas spring hood and gate lifts, etc.)

I’ve never seen factory wiring cause a problem. Every vehicle fire I’ve been involved in that was determined to be electrical involved aftermarket wiring, such as a van conversion, or more frequently, owner installed accessories which were completed in an unprofessional manner.

Not necessarily. That depends on the source and rate of leak.

I saw it happen once in London, a block away from the British Museum. I was on the sidewalk facing Tottenham Court Road, and I saw a red Lamborghini pull up to the curb very suddenly. The driver burst out of the car, nearly knocking me down. At almost the same moment, there was a foom as flames started leaking out from under the hood. Within about 30 seconds the whole car was on fire.

It was one of the more dramatic situations I’d ever been involved in. I still recall the driver (wearing a black suit, looked about in his early 30’s, “City gent” type) trying to apologize for running into me, but being in such shock that he couldn’t speak. I remember the tires exploding–bang! bang!–as the fire reached them. I also remember how there was a policeman on the scene almost immediately to shoo away the crowd of onlookers.

I never got to talk to the gent, who was obviously in no condition to discuss it, but somehow he figured out that his car was about to explode. So I guess the answer to “what do you do if this happens to your car” is “GET OUT,” in neon-sign letters.

I had a car catch fire once, it was an older Ford Escort and the inside of the engine compartment hadn’t been kept clean. There was a lot of oil and gunk on the top of the manifold. I was standing at a light when the engine backfired. This means there is a small explosion that comes out of the carbeurator (ah, the good old days!) The explosion set fire to the oil, leaves and gunk on the top of the engine. This burned and melted the wire harness and lots of other rubbery stuff inside the engine compartment. Sadly a county sheriff used a fire extinguisher to put it out before it could be a total loss, so I had to junk the car. So I would say that backfires are one way to start a car fire.

I had a Ford Fairmount catch fire once. Catalytic converters generate a lot of heat; ours decided to die by using up all its catalyzing at once, and generated way too much heat. Some wiring running next to it caught fire. I was able to put it out with a fire extinguisher, but we used that as a sign that maybe it was time to buy a new car…

I had a Dodge Shadow catch fire on the freeway. The gasket on the fuel pressure regulator (located on the top of the TBI) had cracked and gas soaked the air filter. I guess some of it dripped on the exaust manifold and POOF. I always carry a fire extingisher in my cars, so it only took a minute to put out. Even with the paint on the hood peeled and burnt, I still got $600 dollars for it as trade-in on my last JEEP.

Next time, use more leaves.

Although I’ve never seen a fire caused by this, I have lost count of the number of times my car has been hit by cigarette butts from other cars. What is it with these people anyway? Don’t they have ashtrays? Somehow flipping them the bird just doesn’t seem to be enough.

I think the most common ignition I see is from improperly installed stereo equipment. Not the dash piece usually, but the cables that run to the super duper bass pumpers in the back of the car. The installer will drive a screw through one of the wires which later causes the fire.

I worked a claim this morning where the car caught fire from a factory installed wiring harness. It was an older car. In these cases it’s often caused by the wiring harness coming loose from a mount and subsequent rubbing on a metal frame member abrades the insulation off the wires–happy days soon follow.

Externally the two main sources I see are from kinked/abraded & leaking fuel lines that drip onto a manifold (all hail the 2002 PT Cruiser!), or debris getting trapped on the cat converter, catching fire and damaging a fuel line with obvious results.

I damn near burned up my car by being stoopid. Gave it a real nice tune up but got the spark plug wires crossed (I gave myself a nice pitting for that in fact). The fuel wasn’t burning completely in the cylinders as a result and was being blown into the exhaust system. It pooled in the converter and was smoking nicely. Couple more miles and I would have had a jolly end to an otherwise pointless day in the office.

In my younger days if someone in front of me dropped their butt out the window at a stop light I’d hop out and give it back to them and very kindly advise them that they must have accidentally dropped it. Never got a thank you for that one. I still call people out when they drop their butts on the sidewalk, “Hey, the trash can is over there…”

This happened to my dad a few days after buying a brand new VW Rabbit. One of the glow plugs was faulty and started smoldering. Fortunately for him, he happened to be in front of a fire station at the time.

re. faulty wiring – should I be concerned about the quirky automatic door locks in my '93 Saturn SLII? Usually they work fine, but occasionally they do this very fast lock-unlock-lock-etc. *ad infinitum * (think of the Herbie Hancock video for “Rockit” from 20 years ago) until I manually lock down every lock, whereupon they stop.

Another way cars catch fire – if the driver drives on a flat tire or wheel rim for too long or at too high a speed. You see this sometimes in police chase footage after the tires have been shot out or blown out.

Correction: “…the 1983 Godley & Creme video for Herbie Hancock’s ‘Rockit’…”.


Just pulled out of driveway, gone maybe a hudred yards and smelled smoke and saw orange fire around the clutch/brake pedal openings. Evacuated occupants, grabbed a chloro-bromo-methane extinguisher went to front of car and lifted hood. Almost dropped it as entire engine was engulfe in flames. Propped hood up and directed the extinguisher into the flames. Must have hit the right place as flames subsided quickly and went out. Wiring a total loss and had to be replaced. It was a bad gas pump diapraghm. Took a day to get car (49 Ford) back on the road.

Moral of story:

  1. Get a fire extinguisher for gas + other fires to keep in car.
  2. In case of fire evacuate occupants.
  3. Extinguish fire, but don’t risk life and limb to do so.

I had a truck catch fire when I was driving it; something in the carburetor got stuck in the “drive really fast” position while I was in the middle of Interstate 80. The brakes couldn’t keep the speed down :eek: so I popped it into neutral and let it rev while I coasted to the side of the freeway. This took a while (it was rush hour), and by the time I got to the side and shut off the ignition, the engine wouldn’t stop running, and wouldn’t stop smoking, and then the flames came, and I bailed.

Another time, I had a car start smoking when the thermostat failed. It was awfully hot under there, on an already hot day (and my poor puppy was in the car with me).