Something very bad happened to my 94STS

[The Fred]

I went out to start it and before the first crank it said BOOOM sort of like a mild shotgun blast and then smoke came from the motor (bluish smoke with an almost sulfurish smell to it) mainly from the passenger side and the blast knocked the "32V NORTHSTAR" clip on piece from the front of the beauty cover

What on earth happened

I went out to start it and before the first crank it said BOOOM sort of like a mild shotgun blast and then smoke came from the motor (bluish smoke with an almost sulfurish smell to it) mainly from the passenger side and the blast knocked the "32V NORTHSTAR" clip on piece from the front of the beauty cover

What on earth happened

[JimD]

Sounds to me like a backfire that opened the pressure relief valve exactly the way it was designed to operate.

[Bruce Nunnally]

Another symptom of a fuel pressure regulator failure btw.

[MAC]

I agree, it sounds like the fuel pressure regulator needs to be replaced. I had the same problem with backfiring through the intake manifold when my FPR went bad. When hot, the engine was difficult to start and often resulted in a backfire. Then white smoke with a distinct smell would rise from the engine compartment.

If you're going to replace the FPR yourself you should be aware that the fuel rail O-ring is probably dry and may break. I posted on this topic about going to Ace Hardware and buying a new O-ring just in case. If I remember correctly, the O-ring was size number 48. I substituted the original O-ring with a grommet I bought at Home Depot and a small O-ring which I placed around the grommet. So far, I haven’t had any problems. If you want to buy an O-ring kit from Cadillac expect to pay big bucks ($60+ for the basic kit and I believe it was $200+ for the complete fuel injection kit).

[The Fred]

Thank the lord,

I thought it was doomed !

I can't wait until my paychecks come in (I'll be getting two at once since one was delayed due to an account number change) so that I can get this Caddy nice and healthy and all.. in this case the FPR and the a/c condenser are all I think it needs.... then I am going to sell the automobile so I can make some investments.

[JasonA]

Do the 1994 engines have a pressure relief valve? His is a pre-plastic intake model -- one that used two separate intake manifold halves. There could be a valve in there somewhere, but I've never heard of one for those model years.

[BodybyFisher]

Here is an interesting thread

http://caddyinfo.ipbhost.com/index.php?sho...amp;hl=backfire

[The Fred]

Quote of the day by... me,

"Fred Maxwell: Why don't you buy me a drink at the Polo and loan me your torx wrenches"

[MAC]

Do the 1994 engines have a pressure relief valve? His is a pre-plastic intake model -- one that used two separate intake manifold halves. There could be a valve in there somewhere, but I've never heard of one for those model years.

Since Fred's problem is associated with a "32V NORTHSTAR" then no doubt it has an intake manifold pressure relief valve.

The 1994 Northstar intake manifold is made of Ultramid nylon 6/6, which was developed as a result of a "combined effort" between BASF, Cadillac, GM Powertrain, and Freudenberg-NOK. As a result, BASF received the "SPE Grand Award for the Most Innovative Use of Plastics." The first nylon manifold was developed in 1972 by BASF and Porsche for the 911’s 6-cylinder engine.

[The Fred]

I can't wait to get in this 82828

And, also,

Aha,

This is another very interesting thread

http://caddyinfo.ipbhost.com/index.php?showtopic=5803

[Ranger]

Do the 1994 engines have a pressure relief valve? His is a pre-plastic intake model -- one that used two separate intake manifold halves. There could be a valve in there somewhere, but I've never heard of one for those model years.

I think the '93/'94 models used rubber grommets under the manifold cover bolts. Those grommets allow the manifold cover to lift a bit under pressure acting as a relief valve.