1997 Chevy Astro muffler blew up trying to crank

1997 CHEVROLET ASTRO
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WILSON5454
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1997 Chevy Astro 6 cyl Two Wheel Drive Automatic 20,ooo miles
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tuesday aftrrnoon for first time that day i got in my 97 astro van 4.3 vortec engine to go somewhere.it usually cranks with just afew revolutions no problem.this time i had to turn it over2 times with no result.on the third time it backfired and blew the muffler to smitherines.i ran a scan on it and it came up with no trouble codes.now it seems it doesnt want to crank but its getting fire and fuel.do you have an explanation why this happened and what may be wrong now
Feb 7, 2008 at 8:40 AM
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TECHMAN1
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I'm shooting in the dark here, but I've only been working on Astro's for about 13 years so let's give it a shot.

Fuel injectors have a return spring that closes them and shuts them off when not being called to deliver fuel.

So if you had an injector with a bad or weak return spring, then when you shut the engine off and the fuel pump continues to run for 8 or 10 seconds to prime the next start, that dumped fuel is going to flood the cylinder that happens to have the intake valve open wherever the engine decided to stop.

So the next time you get in and turn the key, you just flooded the exhaust system with raw gas.

By the way, usually in this case, if you check your oil after the vehicle sits overnight, you will see gas on your dipstick floating above the oil, because the piston rings cannot seal well enough to keep it from draining by.

Hope this helps.
Feb 9, 2008 at 12:27 AM