Priming fuel pump causes car to catch on fire

A caller on this past weekend’s show said her hubby poured some gasoline into the carb in order to start a car that hadn’t been started in a while. This can be necessary if all the gasoline has evaporated from the carb bowl. Apparently when the engine started in this case, it had the unintended consequence of catching the car on fire!

I’ve seen this happen before. Usually it is an engine backfire through the carb that does it. I think this is what Ray thought was the cause. But I’ve seen it happen even without a backfire. I think the best way to minimize this from happening is to make sure to securely replace and tighten the air filter onto the carb before starting the engine. While you have to take the air cleaner assembly off to prime the carb, avoid actually starting the engine with the top of the carb open to the air. Put the air cleaner assembly back on first.

Any other ideas about how to minimize an engine fire when priming the carb?

I have used a shot of starter fluid with more success than pouring gas in the carb.

If the carburetor is dry, pouring gasoline into the bowl vent will allow the carburetor to function normally. A syringe works very well but a turkey baster with a short rubber hose will also do the trick. If it’s just a cold start problem pouring a few spoons full of fuel into the dimple of the breather lid with the hold down nut loosened a few turns often gets things going. I have had an engine backfire and the carburetor melt before an extinguisher was located and used. After that mess was cleaned up there were CO2 extinguishers on every pillar and doorway and work station in the shop.

I have extinguished carburetor fires a couple of times for motorists who were running their cars without the air cleaners. I wound up being out the cost of recharging or replacing my fire extinguisher, but its better than seeing someone lose his or her automobile. My dad and brother once ran out of gas and after pouring gasoline into the tank, my brother primed the carburetor with a little bit of gas. When my dad started the car, the carburetor caught fire, but the car was running. My dad floored the accelerator and that sucked out the fire.
I used to always have a fire extinguisher in the car, but I have become careless recently and don’t have an extinguisher in either car at the moment. As a side note, in the old days of carbon tetrachoride fire extinguishers, the extinguisher was useful if one drowned out the engine. Spraying the spark plug wires with the extinguisher would usually allow the car to be started.
I agree that using starting fluid or a spray of carburetor cleaner is better than pouring gasoline down the carburetor throat.

Putting the air cleaner assembly back together before starting is a good way to insure there will be projectiles in the event of a serious backfire. Launching lids and fragments used to be fairly common with newbies and ether. It gets worse for ether because it evaporates before you can reassemble the air cleaner leading to overuse and potential explosions. If you don’t know how to prime a carb or start an engine with starting fluid/spray, pick your poison; loss of facial hair or a lid to the kisser…

One of my first jobs as a kid was part time gas pump jockey. One frigid night the station owner (I’ll call him “idiot”) was working on a car that wouldn’t start in a service bay. He had the brilliant idea of filling a coke bottle with gas and have me dribble it into the carb while he was turning it over. Well, you can guess what happened next. The car backfired through the carb starting the bottle on fire. I jumped back spilling the gas on my arm (luckily I had a heavy parka on) dropped the bottle which shattered and started a fire on the floor. 2 fire extinguishers, one burned up battery charger, one slightly charred coat sleeve later it was all over. I quit that night.