It blew up!

I have a 2001 Impala with a 3800 series 2 engine. The car has 60000 miles and was sitting for about 6 months. I changed the battery and turned the key and the whole top of the motor blew off in a big explosion. Parts flew 20 feet away and I had a fire that took 10 minutes to get out. The plentum blew away and you could see inside the engine. Any ideas why? The only problems i had since the car was new were a cat converter and the fuel pressure regulater were changed under warrantee. Please help! Tom

“Any ideas why?” By any chance was Gas or starter fluid spray, or poured into the plastic intake plenum to assist in starting, that could have caused such a event?

I know better than that. I just got in and turned the key. Never had a problem starting. seemed the engine was full of fuel.

Like you said, sounds like it got flooded, and had a nasty back fire. I don’t why but think Dorman makes a replacement intake plenum manifold that I you can get at for about $100.00 if thats the only damage.

The fire did too much damage under the hood. GM is looking at it but I dont want them to tell me it was my fault. How would a fuel injected car get flooded? Something leaking? Bad enjector? Fuel regulater?

The oil pan probably has a fracture in it too. This was a common malady in the old 440 Mopars with the Thermobog carb. fuel leaks in and saturates the oil and with conditions right the entire inside of engine will explode. Somehow you have a fuel leak into the crankcase. LEE

There was a recall on those engines for a leaky fuel pressure regulator diaphram that was causing engine fires. My 98 Park Avenue had the diaphram replaced under the recall. You might want to check into that.

Fuel got into the engine either from one or more fuel injectors leaking or from a leaking fuel pressure regulator. In either case, fuel ends up pooling in one or more cylinders.

The ignition system on your vehicle is a Wasted Spark ignition. This means when a coil fires, it sends a spark to two cylinders. One cylinder has the proper air/fuel mixture and is ready to be fired. While the other cylinder doesn’t and the valves are open.

If there’s fuel in any of the cylinders where the wasted spark is suppose to occur it can, well, you found out!


thanx Tester. that was the line i was thinking on. Do youi think it could damage the engine enternaly? Would you think GM would fix it as there were recalls for faulty pressure regulators?

A quick look at ALLDATA shows there is no recall on a fuel pressure regulator for your car; however, there was one for the previously mentioned Buick.
The only fuel system items mentioned on your vehicle are just generic TSBs, or Technical Service Bulletins.

The fuel pressure regulator can be easily tested and if this is the cause a polite conversation with the regional office might get it fixed for you. It’s a long shot, but possible.
My inclination is that the problem was likely caused by a fuel injector that hung open. The car had been sitting for six months and it’s possible that when the pintle on the injector retracted on the first go around it may have stuck open. This would lead to an injector spraying non-stop and of course this gas fog that is being produced is going to back up into the intake manifold when the intake valve closes.

Of course this may be difficult if not impossible to determine now since the resulting explosion could have “unstickied” the injector. If the fuel pressure regulator is good then the injector is likely the fault.

ive seen cases, where the car shut off right when the intake valve was open, and the already flooded car had gas seep down through the rings and into the oil. it is very common with air compressors, but most of them wont start when this happens

Sticking parts seem reasonable on a car that sat for 6 months. Tom, was fuel stabilizer used before the car was idled? If not, and possibly even if, fuel stabilizer was used, the higher weight components of the gas could make the pintle stick. You might as well be straight with them. That might buy you something. Also, you might check with your auto insurer to see if you can get something from them for this “accident”. Hey, they gave me a new windshield when I broke it. Silly me tried to pry off the wiper by resting the pry bar on the cowling below the windshield. Well, almost below. I called the insurer, explained exactly what happened, and they replaced it - even though they knew that I broke it myself.

no but u can get a large piece of trash stuck in the injectr and it would drip while it sat