KABOOM! Then white smoke from under hood when starting 99 DeVille?!?

[mychelleDeVille99]

Anyone heard of this? I was stopped at the gas station, parked and shut off the car. Upon returning, I turned the ignition over, and BOOM! Like a loud explosion or backfire from under the hood, and tons of smoke pouring out. People were running and grabbing fire extinguishers, etc. The smoke settled down and there never was a fire, the car did start then, but not quickly. I drove home then and it seemed to run fine. Is this a serious thing? A fire hazard perhaps? Or just one of those things that happens once and never again, becuase the gas flooded or something? It seemed dangerous, but maybe wasn't? This might be the last straw for me, and out comes the "For Sale" sign. Any help would be appreciated. By the way, 1999 DeVille, Northstar - 95,000 miles.

[Ranger]

If you look at the front of the intake manifold (right behind the P/S pump), you'll see a hole and in that hole is a spring loaded flapper door. It is an over pressure relief valve. In other words it give expanding gases somewhere to go in the even of an over pressurization (backfire), as opposed to blowing up the manifold. I suspect that you have a leaking FPR. When you shut down, it leaked fuel into the manifold until fuel pressure dropped. That fuel sat in the manifold til you cranked it up again and instead of getting ingested, it ignited and KABOOM.

[z06bigbird]

You obviously do not have any youngsters, or they definitely would not let you sell a car that EXPLODES every once in a while. Kool, man.

[codewize]

Ranger, you always amaze me at the things you know. Why on earth would you even know something that complex and abnormal.

[I~LUV~Caddys8792]

Originally Posted by codewize

Ranger, you always amaze me at the things you know. Why on earth would you even know something that complex and abnormal.

Totally. Ranger is the man.

[Ranger]

It's a gift.

[Playdrv4me]

Originally Posted by Ranger

If you look at the front of the intake manifold (right behind the P/S pump), you'll see a hole and in that hole is a spring loaded flapper door. It is an over pressure relief valve. In other words it give expanding gases somewhere to go in the even of an over pressurization (backfire), as opposed to blowing up the manifold. I suspect that you have a leaking FPR. When you shut down, it leaked fuel into the manifold until fuel pressure dropped. That fuel sat in the manifold til you cranked it up again and instead of getting ingested, it ignited and KABOOM.

Whoa... dood, thats not even something the DEALER would know.

[Ranger]

If I know it, any dealer mechanic worth his salt should know it. I'd bet Ewill3rd would have come up with the same diagnosis if he got to it first. That is assuming I am correct.

[Playdrv4me]

Ya I know... but you deserved props for that one brother.

[Ranger]

well, lets see if mychelleDeVille99 confirms a leaky FPR. Then I can accept the accolades. If not,

[tankaillc]

Oh I just can't wait for this to happen to mine. I've already had improper combustion problems which have been fixed. Mine wouldn't always fully start.

The dealer explaintion was that mine would throw in the fuel and spark but the engine wouldn't turn completely over. So I have to start it again but my white smoke came out the tail pipe on the partial start.

That was about a 8 months after I got my 99 deville. I'm tying to remember what all was done on that vist to the dealer the only thing that comes to mind was somthing about a dirty/build up in the throttle body or was the intake manifold. After 5 years and many trips to the dealer for repairs I don't remember all the details.
Present mileage is 30,125. And yes it's at the dealer awaiting yet another round of fixing. Hence why I have the 93 fleetwood brougham my trusty backup car\family taxi when there car is broken.

[mychelleDeVille99]

Thank you guys! You are all so smart AND funny... you must have lucky Cadillac driving wives...
Anyways, its at the mechanic as we speak, so hopefully soon I will have an update for you to confirm or deny your suspicions. I now have a new mechanic because the other ones were so tired of me coming in every Friday with a new problem... They would just roll their eyes at me. You might think they would like all the money I give them. Oh well. I am one of those nervous types who likes to know everything is working properly. Unfortunately, this car does nothing to relieve my anxiety except something beautiful to look at out the window. I will know tomorrow if its For Sale sign time.

One more discussion point: This car has EVERYTHING, but no cupholder?? Oh, sort of a cupholder inside the arm rest.... I know what direction I'm heading and the temperature, but I cannot drink a beverage while driving. What gives?

[Ranger]

Is this what your looking for? Better hurry, only 7 min. left.

http://cgi.ebay.com/ebaymotors/Cadil...12372958QQrdZ1

[codewize]

Yeah I'm thinking someone hijacked the cup holder. I understand. I'm not nervous but more of the anal type who like everything in a vehicle to be proper. Things need to look and work correctly and if they don't I scramble to figure out how to make it right.

I guess we're certified car crazy

[mychelleDeVille99]

Originally Posted by Ranger

well, lets see if mychelleDeVille99 confirms a leaky FPR. Then I can accept the accolades. If not,

You were correct. Had it replaced, which should fix the slow starting problem and increase gas mileage!! I also had the blower motor fixed for the third time, if anyone keeps count of these things, this time with a new one. The others were used, and I obviously should have done that first. Shocked and astounded by the cost of all of this. I should have known better.

Speaking of gas/gas mileage, my new mechanic said I probably don't need to use premium gas. Am I just an idiot for using it? For whatever reason, I feel uncomfortable not doing what I am told. Premium or not?

Thank You !!