Josh91Bird

Started car everything normal, backed out of driveway, drove down the road fine and then BAM! huge single backfire out of the exhaust, engine went dead, let it coast to a stop. I did a visual inspection under the hood and did not notice anything abnormal. Attempted to restart the motor, the engine turned over like normal, was getting plenty of fuel but would not fire.
Has anyone had this happen or know what it could be? Any suggestions would be appreciated. Thanks

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91 Firebird 305/TBI - cam:.420/.442 204/214 - Hooker 1 5/8" headers - TFX PaceSetter Cat-Back - 3.42's Auburn Pro Posi - ASCD Ram-Air hood - Polished Formula Wheels w/Futura's - Open element - .5" Corian TB spacer - Lakewood LCA's - Hotchkis Lowering Springs - KYB Struts/Shocks - 14.78 @ 97.5 mph(G-Tech) - MacEwen MotorSports Whiteface Overlays - 412ci sb waiting to go in this spring.
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Engineboy

Are you getting spark??



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ASE Mechanic/Machinist/Smog Tech

1999 NBM Trans Am
1986 Chevy 3/4 ton pick up
1981 corvette
1995 Kawi ZX6R

GO #3

AlkyIROC

Sounds like a spark problem to me also. Pull the distributer cap off and see if the rotor is turning while cranking the engine.

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Stephen's racing page

87 IROC-Z Pro ET Bracket Race Car and knocking on the SuperPro ET class
383 stroker (carbed) with double hump cast iron heads and pump gas
LS6 Big Block buildup now in progress

Best results before the engine blew up
Best ET on a time slip: 11.857
Best corrected ET: 11.163
Best MPH on a time slip: 117.87
Best corrected MPH: 126.10
Best 60 foot: 1.662

Racing at 3500 feet elevation but most race days it's over 5000 feet density altitude!

Member of the Calgary Drag Racing Association

Josh91Bird

I am going to check in the morning. Sounds to me also like a no spark problem. But what explains the backfire and then dead motor? Any guesses

Engineboy

Its rare, but if you broke a timing chain the dist. fires at the wrong time and POP goes the backfire.

I have heard of a module backfireing before dieing.

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ASE Mechanic/Machinist/Smog Tech

1999 NBM Trans Am
1986 Chevy 3/4 ton pick up
1981 corvette
1995 Kawi ZX6R

GO #3

Josh91Bird

If the timing chain would have broke, The cam would stop moving and thus the valves would be hitting the pistons correct? If this was the case I should be hearing some horrible sounds while i was turning the motor over correct? When you say module do you mean the module in the distributor?

AlkyIROC

Distributer drive gear could have spun also. It's only held in by a spring pin.

When you pull the cap off to see if the rotor is turning, check also if it's in the right position. Rotate the engine so the timing mark is at TDC. The rotor should be pointing at #1 or #6 plug wire on the cap or very close to it.

If everything checks out ok then pull a plug wire and plug and see if it sparks while cranking. If not then go for a module.

Engineboy

On some motors (mostly OHC and import engines) the pistons will smack the valves when the cam stops and the crank keeps going.

I've never seen that on a SBC. I could see it happening if you have a big cam or high comp. pistons.

FWIW...You can't hear the valves/piston contact while spinning the engine when a timing belt/chain breaks. Its silent death.

Yes, the module in the dist.

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ASE Mechanic/Machinist/Smog Tech

1999 NBM Trans Am
1986 Chevy 3/4 ton pick up
1981 corvette
1995 Kawi ZX6R

GO #3

[This message has been edited by Engineboy (edited October 24, 2000).]

Josh91Bird

Update. The rotor turns normal. Not getting any spark out of the coil. I replaced the coil not too long ago. WOuld the module going bad cause the coil not to spark?

Josh91Bird

Well it was the coil the whole time. It was a coil from autozone...I guess they don't last longer than a year or so. Well I bought another $16 coil...but I will have the new motor in before this one goes bad hopefully. Thanks everyone.

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91 Firebird 305/TBI - cam:.420/.442 204/214 - Hooker 1 5/8" headers - TFX PaceSetter Cat-Back - 3.42's Auburn Pro Posi - ASCD Ram-Air hood - Polished Formula Wheels w/Futura's - Open element - .5" Corian TB spacer - Lakewood LCA's - Hotchkis Lowering Springs - KYB Struts/Shocks - 14.78 @ 97.5 mph(G-Tech) - MacEwen MotorSports Whiteface Overlays - 412ci sb waiting to go in this spring.
My Homepage