1995 Chevy S-10 Rough Startup

TPALMER03

MEMBER
1995 CHEVROLET S-10

Engine Performance problem
1995 Chevy S-10 6 cyl Two Wheel Drive Manual 201K miles

Hello. O have a 1995 Chevy S-10 V6 4.3L TBI with a Vortec engine (engine block is probably from a 98 S-10). I have been experiencing a rough startup that appears to be getting worse. Usually at startup when the block is cold the choke kicks in and starts the engine at a high rev before smoothing out to a normal idle. Right now when I startup I get a rough startup with pretty rough vibration of the entire truck as if a major misfire was occuring. Then I either pump the break, clutch, or gas pedal to force the truck to choke. The truck will then go to high rec and eventually (~1-2 min.) Go back to normal idle. There is a smell of rich fuel after hitting the gas pedal. I have replaced O2 sensor, cat. Converter, spark plugs and wires, radiator, temperature sensor, engine coolant sensor and the thermostat. BTW, no lights are on in the dash at all (no check engine light).

1 Reply

HMAC300

MECHANIC
48,601 POSTS

TBI units had a habit of the gasket breaking below teh TBI unit itself. You can either spray some choke cleaner around the base of the TBI to seeif it leaks, do this at idle. If the car wants to smooth out the idle or stall, it probably leaks. Also the hose going to the PCV gets soft and closes off when started. THen lastly the hose going to the MAP sensor also gets soft and closes off the vacuum source to that as well. YOu should never ever change any sensor to fix things without getting the engine scanned first. As you are saying it's mostly a startup condition it kind of tells me the cmputer is richening the fuel mix enough to let ethe engine run well. So i'd go for the vacuum leak.