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I have a 1995 chevy K3500 5.7L tbi, 4 door, AC\heat, power windows mirrors locks seats.
It's having a power\ acceleration problem, hard shifting, no check engine light is on. It's like the engine doesn't want to open all the way up with "pedal to the metal" after 60mph slowly climbs I took it to the Chevy dealership here in Jacksonville, Florida. They told me that they are unable to scan my vehicle because it's OBD1 and that I might possibly need a new ECM for them to read it and maybe wiring issues they don't know they can't find any wiring diagrams for either because of the age. They don't know what's wrong with it because they can't scan it so now I need to find a good working ECM I don't know where to find one compatible to my vehicle and one that works and who sells one where can I find an ECM compatible to my vehicle?
168919
 

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‘01 Silverado 2500HD 8.1/Allison 5sp xcab long bed
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Save your money. Start by checking and measuring. Parts roulette does not work and delays successful diagnosis. The computer is almost never the problem but because it has one, those who can’t diagnose find blaming the ECU easy.

There’s a reason some call them stealerships....

You don’t necessarily need a scanning tool to check OBD1 codes.

168920

With a paper clip, jumper A-B, Turn the key on but do NOT start the truck. Your service engine light will flash a pair of numbers. One flash, two flashes represents 12. Each code will be presented three times then cycle back around to 12 again.
Remove the jumper before starting.

Get your hands on a TBI fuel pressure test kit. Test your fuel pressure with the key on and truck not running. Then, start it and check at idle and under load.

Report what you find.
 

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If the check engine isn't on, you shouldn't see codes, except for the 12, which just tells you the port is good and the computer is ready.
Like Greg, I suspect a fuel delivery problem, although, it could be a dirty throttle body, or a restriction in the air filter.
It could also be a spark problem; but that should flash the CEL.

EDIT, it could also be an exhaust restriction, maybe the cat
 

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Discussion Starter · #4 ·
Save your money. Start by checking and measuring. Parts roulette does not work and delays successful diagnosis. The computer is almost never the problem but because it has one, those who can’t diagnose find blaming the ECU easy.

There’s a reason some call them stealerships....

You don’t necessarily need a scanning tool to check OBD1 codes.

View attachment 168920
With a paper clip, jumper A-B, Turn the key on but do NOT start the truck. Your service engine light will flash a pair of numbers. One flash, two flashes represents 12. Each code will be presented three times then cycle back around to 12 again.
Remove the jumper before starting.

Get your hands on a TBI fuel pressure test kit. Test your fuel pressure with the key on and truck not running. Then, start it and check at idle and under load.

Report what you find.
Ok thanks a lot. I was surprised they have no clue at all
 

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you shouldnt be , most of those techs were in high school when your truck was built , maybe in diapers , i have a 98 and most modern techs dont know anything about it, they never worked on them before. remember the technology has progress quite quickly in the past 30 yrs or so , the techs that worked on 95's are fewer and far between
 

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The OBDI TBI system will turn on the SES and most times will turn it off but, it'll store the code for up to 30 -40 key cycles or, if you disconnect the battery. There may be a code or 2 which may point you in the right direction. If you have low fuel pressure it won't set a code for that but it may for low O2 sensor. As Greg said, you can do the paperclip trick. Here's some more info on that.
 

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Discussion Starter · #7 ·
The OBDI TBI system will turn on the SES and most times will turn it off but, it'll store the code for up to 30 -40 key cycles or, if you disconnect the battery. There may be a code or 2 which may point you in the right direction. If you have low fuel pressure it won't set a code for that but it may for low O2 sensor. As Greg said, you can do the paperclip trick. Here's some more info on that.
Thank you very much
 

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I have a 1995 chevy K3500 5.7L tbi, 4 door, AC\heat, power windows mirrors locks seats.
It's having a power\ acceleration problem, hard shifting, no check engine light is on. It's like the engine doesn't want to open all the way up with "pedal to the metal" after 60mph slowly climbs I took it to the Chevy dealership here in Jacksonville, Florida. They told me that they are unable to scan my vehicle because it's OBD1 and that I might possibly need a new ECM for them to read it and maybe wiring issues they don't know they can't find any wiring diagrams for either because of the age. They don't know what's wrong with it because they can't scan it so now I need to find a good working ECM I don't know where to find one compatible to my vehicle and one that works and who sells one where can I find an ECM compatible to my vehicle? View attachment 168919
Throttle position sensor controls shift points and throttle response,easy to change (on side of throttle body) and relatively cheap! Thats where i would go !
 

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Throttle position sensor controls shift points and throttle response,easy to change (on side of throttle body) and relatively cheap! Thats where i would go !
You can back probe the TPS with a volt meter and see if it goes smoothly from around 0.45V to 4.5V+ when you depress the skinny pedal. I know sensors are fairly cheap but, why throw parts at it just hoping it'll fix it?

Did you check for codes yet?
 

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Have you ever changed the fuel filter? Autozone does list an outboard fuel filter for your truck.

My 2002 Astro, the fuel pump was in the gas tank but the fuel filter under the truck was clamped to the frame. I didn't have a problem but I changed it out at 90k on the clock. Out of curiosity, I cut it opened and I was amazed how any amount of fuel was able to get through. About 10,000 miles later the fuel pump totally quit, dead in the water.
 
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