L36 intake exploded!

Turned the key on my 96 Regal and there was a loud boom from under the hood. Lots of gray smoke was still coming out as I pushed the car out of the garage luckily there was no fire when I opened the hood.

The plastic upper intake manifold exploded on the parrengers end of the plastic manifold. It bent the fuel rail up and lifted number 2 injector out of its bore not sure if it is broken. One large chunk of plastic blew up and dented the hood and is sticking down out of the hood insulation blanket. This is my fault for not having the motor cover in place.

I just checked the Fuel Pressure Regulator with a piece of vacuum hose and there is no fuel leaking there?

What is the most likely cause of this explosion other than the Fuel Pressure Regulator?

My condolonces on the loss of your intake manifold. I had the same thing happen, except mine was accompanied by a fire. Just getting it back together now. I expect you will need to replace your fuel rail, given the extent of the bend it must have suffered. I found a used one for $75 that included the injectors. The intake manifold isn't too expensive either.

As for the cause, that may be difficult to diagnose. Were you having troubel starting the car? Backfires are not uncommon when a car is starting hard.

this is not the first time that we have heard this type of Failure, we lost a SLE 2 years ago and just recently lost a SSE about 4 months ago

Theres a recall for a fuel pressure regulator. If yours hasn't been taken care of you may get this repaired under the recall.

Didn't we just have another user get this fixed free a few months ago?

Phill the car has never had any starting problem before today.

1993 SLE did you ever find the cause of the explosions?

My fear is to replace every thing and have the same thing happen.

I wasn't aware of these catastrophic failures.... that'* really interesting. There certainly had to be some kind of "backfire" or pressure reversal for this to happen. Could it be a timing chain that jumped teeth and caused a compression stroke to revert through the intake?

And related to my previous post, how many miles are on the car?

I am the guy with the 98 SE that exploded a couple of weeks ago. I have another thread going as I try to get the car running again.

Yes, I thought of all those things. I replaced the FPR, even though it tested OK and had already been replaced on the recall. I checked the compression and it is reasonably good, so the valves seem to be closing at the correct time. When I had the intake manifold off everything looked OK, but you can only see the push rods and the intake valves. I didn't get any codes so I don't have any other clues yet. As soon as I get it running, I will post back to let you know how it runs.

By the way, I call it an explosion, but really it was a bad backfire that broke the plastic UIM and dislodged the fuel rail. This caused the fire.

This is a 1996 Regal 3800 II motor with 65,000 miles.

The “Fuel Pressure Regulator” does not seam to be the cause of this explosion.

Because of this forum I have been checking for Pressure Regulator for leaks several times a year.
There is no fuel in the FPR vacuum line and I can not suck any gas from the FPR vacuum port.

Well, what could have caused such an explosion? It would have had to be some kind of compression or power stroke reversion through an intake valve, wouldn't it? So it could be either a mechanical or electrical timing issue.... either the cam and crank are out of time, or something is happening electrically to make a plug spark prematurely?