Upper Intake Manifold Exploded and Started on Fire

[indygrandprix]

So I hadn't started my 01 GP in a couple months. I put a battery in it one night and went to crank it over and there was a huge bang and then I saw fire under the hood. Ran and grabbed my fire extinguisher and put the fire out and this is what I was left with.


So after doing some digging on the internet I still am not sure exactly what cause this to happen. Most people point to the fuel pressure regulator but I don't understand how the fuel/air mix inside the intake would have ignited even if the fuel pressure regulator is bad. I have a new dorman replacement kit for the upper intake but I really dont want to put it on just to have the same thing happen.

Thanks for any help

[SubwayGuy]

Yep, Bill told me about this. This is why it's important to get your FPR changed if it's bad. It blows gas out of it which gets sucked into the intake and all it takes is a single spark to blow it up. Not really sure where the ignition comes from, but clearly it can happen.

It's the FPR that caused this. I would pull the blown intake off and give a once over to everything else. Chances are something else broke or started on fire and is melted.

Sorry this happened to you.

[Burbman]

Holy backfire Batman!

[Fivefingerdeathpunch]

It can happen if the fuel injectors leaked fuel aswell, the fuel vapors will just rise up and when one cylinder fires off it will just go boom and that's the weakess link.

[idrivejunk]

Thats bizarre, and what a bummer. My bet is a stuck or slow valve, an intake that didn't close or didn't seal for whatever reason, in conjunction with the aforementioned likely fuel issue. The world may never know. Good luck with the fix. If you were here I'd hand you a good OE UIM.

[02NavyBlue]

+2 on the FPR being the cause. Change that and the intake (and inspect other things around the blow out) and you'll be good.

The 3800 is a good engine, but man it sure has some strange problems. What other engine does this?? Lol

[16MustangVet]

oops too big of a nitrous shot.

too soon jr.

[indygrandprix]

Yeah it was quite a bang. I didn't know that my FPR was going bad or was bad the car ran fine when I parked it but I guess I will replace it along with having the injectors tested and possibly rebuilt.

I have pulled the pieces of what was left of the intake off. The wire tubing was melted but all the wiring looks ok. The high pressure fuel line got melted pretty bad so I have to replace that which sucks but I can get that line from the junkyard for cheap. Thanks for the help guys. Very much appreciated

[stealthee]

This isn't an oddity with GM or the NA 3800. I have seen numerous posts over the last few years over a few forums with the exact same thing happening.

The biggest problem is the plastic intake manifold. With a cast (iron or aluminum) manifold there might still be a backfire, but the manifold wouldn't explode.

[02NavyBlue]

You've seen other engine's plenums blow from a backfire? I'm interested to know what other engines that happened on.

[stealthee]

1st gen Neons have a plastic intake manifold and it has happened on them as well.

[02NavyBlue]

Hmm. Some of them have rubber intake tubing just like we do on 3800's, but it's after the throttle body, not before. So it's in vacuum and also susceptible to blowing out I guess.

[indygrandprix]

So I grabbed a new fuel line from the junkyard and put it on the car cuz the old one melted the hose connector and plastic clip on the rear fuel rail but when I primed the fuel pump to check the injectors to see if they where leaking I got a bunch of gas leaking really badly around where the hose connects to the fuel rail (it is the larger hose on the rear of the fuel rail that leaks) I am wondering if there are different sizes of hoses between the cars or if the hose just has bad o-rings. I did have to take a wire wheel to the metal nipple to get the old melted metal off so maybe that was too abrasive?

[02NavyBlue]

It's possible that the wire wheel took off too much, but I know those leak even without damaging them. I'd put new o rings in it first

Sent from my HTC One_M8 using Tapatalk

[CrazyGuy03]

3 times this year already I seen this happen. What is going on?!

[Scottydoggs]

inside the quick connect is two o rings, they go bad and leak if that where the leak is.

[stealthee]

3 times this year already I seen this happen. What is going on?!

As I said, this is ridiculously common on the NA 3800.

Just look at the google results https://www.google.com/search?q=uppe...utf-8&oe=utf-8

[BillBoost37]

Double check that your car didn't have a recall. Some of the years were recalled by Gm and even if they were ignored...gm will take care of you.

[J57ltr]

My friend had this happen to in his 96 Bonnie. It was pretty common from what I recall.

Jeff

[indygrandprix]

Well it ended up that even after replacing the o-rings it still leaked so moral of the story I guess is don't take a wire wheel to your fuel rail nipple or you'll be buying a new one. Once I got it hooked up and not leaking I primed the fuel pump and saw no leaks coming from the injectors so it must have been the regulator that made it ka-blamo.

Thanks to all who offered any help! I greatly appreciate it.

Also I did check to see if there was a recall on mine dealer said only recall they showed for it was the valve cover gasket but I already replaced that shortly after I got the car.