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Discussion Starter · #1 ·
Long story short, drove my truck home from college for winter break and the truck ran fine, actually it seemed to be running better then normal. Only thing is is I got home, parked it - still running great - and 4 days later go to turn it over and all it does is spit and sputter and backfire when im on the starter. Checked for spark, checked fuel, check cap and rotor and ignition is fine. Only thing is is I'm certain it's getting to much fuel because of all the back firing and stuff. Anyone have any idea's what kind of tests I can do to figure out whats wrong with it?
 

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is it a 4.3L v6? isnt it fuel injected also? does it do anything more when turing it over and you apply just a touch of throttle? is the computer throwing any codes that you know of?
i would start with cleaning the Mass airflow sensor with some Brake clean. i would then have a look at maybe your Throttle positioning sensor. maybe its shot or going. unplug it and give the connections a good cleaning. (also with the MAF you could unplugg it. will set off a code though but wil run fine.)
just some thoughts. hope it helps
 

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Discussion Starter · #3 ·
It is a 4.3 V6, fuel injected, ZR2, tried a touch of throttle, computer didn't throw any codes. Cleaned mass airflow, haven't touched TPS. Tried starting it without MAF plugged in, hell tried starting it without any aircleaner on it, still nothing but backfiring and bitching...
 

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very odd. usually really reliable motors and trucks. hmmmmm got mes thinking i am really wondering about that TPS sensor. fuel filter changed? i will dome research and see what i can come up with for ya :)
Thanks
Logan

if you have access to a scanner i would hook it up and just see if it has any hard codes stored. never hurts to see if it says anything. just read on a gm forum that the new vortec motors are sensative to fuel pressure so if the fuel pump its crappin out it could run like crap and so on.
 

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Discussion Starter · #5 ·
Ok, I have a hypertech programmer that will read only non running trouble codes, the only thing it throw was mass airflow performance and misfire; It has a K&N Cold air intake and when my dad had it, he pounded a hole through the cat - which makes the thing run like crap if it throws a catalyst code but right now with the cold it feels like a V8. It hasn't thrown any other codes besides those two.

Fuel filter has maybe 20,000 on it and is there any way to test a TPS?

I should also throw out there that this baby does have 179,000 miles on her so maybe think routine maintenence that the average joe doesn't know about.

Thanks for the help!
 

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Problay sounds stupid, but you got gas in the truck?

Hope you get it up and running before school starts. My 2005 blazer is up for a major tune up in the spring.
 

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check fuel pressure, their is a shrader valve with a black cap to the right of the distributor as you look from the front of the truck. with the center depressed you should have good fuel pressure, cranking. also a weak spark is considered no spark. most likley no fuel. good luck
 

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the Vortec motors I believe need 55-60 PSI of fuel to open the poppet nozzles that are inside the intake. If they do not have enough pressure they will not open. I would start there willing to bet that is the problem.
good luck
 

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Discussion Starter · #11 ·
BskidooC said:
exhaust or intake backfiring?
Intake backfiring like a son of a bitch...
 

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heard of this problem beofre...ur have that stupid spyder injection fuel system under the intake manifold...alot of times the main casing just cracks and causes problems like that
 

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Heston383 said:
heard of this problem beofre...ur have that stupid spyder injection fuel system under the intake manifold...alot of times the main casing just cracks and causes problems like that
you said your cap and rotor are good??? you sure? i broke 4 rotors on my 97 within a couple months....never found a cause either.....
test the ignition module, and cam sensor if your sure the rotors good and you are getting fuel!





just thought about something really stupid......any of your friends ever play tricks on you???? check your firing order!
 
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