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Non-stop black smoke and barely running

Gabriel Temple

By Gabriel Temple
in Ask A GM Technician

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Gabriel Temple New Member

Gabriel Temple

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Yeah I have a 1990 square body crew cab 1 ton silverado with a 454 that I recently bought and the thing black smokes when you give it gas and trying to figure out what is the problem. Changed the oil and using Royal Purple gas cleaner. Haven't changed plugs or rotor or distributor cap yet. Looking for some info please.

Jsdirt Senior Enthusiast

Jsdirt

Posted
Posted

Do a visual inspection of the injector spray pattern - if that's good, check fuel pressure - could have a bad regulator. If the fuel system checks out, then move on to ignition.

 

Injector problems happened quite a bit on those, and the bunch of other models that used them in the day. They're super reliable in most cases, but there were a few that liked to dribble fuel instead of spray it. After 27 years, anything is possible, but that would be the first thing I check. Get a nice, bright light, or even better, a timing light to see how the pattern looks.

Gabriel Temple New Member

Gabriel Temple

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Not really sure about burning oil or too much fuel or any of that but I know someone put a crappy exhaust on it so it has not cats that I've seen but clamps on the exhaust are broken or rusted to pieces so it's basically just sitting there hanging by the hangers. I'm thinking about changing the tbi to a actual carburetor but not sure how that would affect the computer.

Jsdirt Senior Enthusiast

Jsdirt

Posted
Posted

Great thing about those trucks is, you can carb it and keep the transmission hooked to the computer, and it will still lock the converter - and as long as you have the oil switch hooked up still, the fuel pump will run just as it did prior.

 

You'll need an HEI distributor assembly (like a DUI unit), and a fuel pressure regulator if you plan on using the existing fuel pump. Can't have much more than 5psi going to a carb. These TBI units run about 40 PSI or so.

 

Converted a 2000 4.3 V6 this way, and dropped it in a '89 S10. Was the most fun vehicle to drive in my fleet since I sold my '72 El Camino. :)

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