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Discussion Starter · #1 ·
New to the forum .. got an issue ..Got my truck 2000 Chevy Silverado 4.3 Vortec auto 200k miles doing something weird lately, idles good, runs good but when it hits 1500 rpm it starts running sluggish and back fires .. replaced the plugs, cap, rotor,wires, and nothing coil was replaced too, codes is throwing is p0785 .. which is shift timing solenoid, which is a tranny code but tranny shifts fine thru all gears .. what can it be ???
DSC00251_zps54304e8e.jpg
 

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Could be the CSFI spider.

WHats the fuel pressure? Should be around 58 psi and jump to 62-66 when you open the throttle quickly.

peace
Hog
 

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dose sound like a fuel dump. also check the CTS.
 

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That usually happens with the 4.3 is trying to find the other 2 cylinders that used to be attached to it.
 

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clogged cats
 

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Discussion Starter · #7 ·
fuel pressure is at low 50s at idle and not even hitting 58 on full throttle..

Does this means it needs a fuel pump ??

IMAG0297_zps3315e392.jpg

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when was the last time you changed the filter? and yes could be a pump also.
 

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Discussion Starter · #9 ·
I just changed the fuel filter now and it runs better but not perfect, the gauge stayed the same same as pics no change in PSI
 

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its been like 2 years since i had to mess with my now sold 4.3l. the thing is its seems like the pressure is like 3-4psi lower then needs be. you could take the intake off and smell in the throttle body and see if you have a gas smell. that would mean the regulator is busted or a cracked spider.
 

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look and smell threw the throttle body to see if its wet in there.

also take a ohm meter to the coolant temp sensor (plug next to the thermostat) and measure the resistance on a cold engine.
 

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Any smoke from tailpipe?
 

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Discussion Starter · #16 ·
truck is running better, but seems that when its cold it acts up, Im gonna replace the CTS since its not that much to replace.. truck seems sluggish still thou..

Didn't have a OHM meter turns out..
 

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I still say cats
 

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Discussion Starter · #19 ·
truck is running the same... WHAT could it be ? got a new distributor didn't want to throw it on but should I ?? a;; codes were cleared out, the intake manifold was completely dirty including the throttle body, cleaned it out good and no change... FRUSTRATED !!!!!!!:mad:
 
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