running horrible

[bigred91]

I have a tbi 350 in my 1991 chevy. It will practically not even start when its really cold out. it fires up then dies right away after like 2 seconds of idling. Also when driving at highway speeds and i punch it, it falls on its face and basically looses all power. I have replaced the distributor, reset the timing at 0, cap, rotor, plugs, wires, iac, coil, tps, basically every module on the motor. any info is helpful guys. thanks

[C & A s Dad]

At this point I would suggest that you seek the help of a Professional Technician. I wish I could offer some advise but it sounds like you have run the course.

[bigred91]

Ya it sucks my truck has been at the local GM dealership for the last 3 days with them spending hrs on it trying to figure it out and still nothing. o well

[Cadha13]

I think you got a fuel delivery problem, like a plugged filter or similar. Sounds like fuel starvation

[Chestah]

I would say Fuel Filter, but if it's been there for 3 days I'd have to say it's something a bit more complicated.

 

 

Hope you can get this sorted out.

[bigred91]

fuel pump, and filter have less than 50 miles on them. both brand new quality units. it seems like it is flooding itself in the morning. im startin to lean towards timing chain/ or computer or both. this problem is makin me wanna sell the chevy for a newer one!!

[billcar9999]

I have a tbi 350 in my 1991 chevy. It will practically not even start when its really cold out. it fires up then dies right away after like 2 seconds of idling.  Also when driving at highway speeds and i punch it, it falls on its face and basically looses all power. I have replaced the distributor, reset the timing at 0, cap, rotor, plugs, wires, iac, coil, tps, basically every module on the motor. any info is helpful guys. thanks

 

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I had a temp sensor do that. It was going extremely rich.

[bigred91]

the temp sensor?? is that the sensor that plugs in up by the t-stat?

[bigred91]

it wasnt any of the sensors. I found that my timing chain has jumped and thats what is causing it to run so crappy. looks like the poor truck is gonna sit at my work for a LONG time until I can afford a motor. time for the corvette engine!!

[Honda tech]

it wasnt any of the sensors. I found that my timing chain has jumped and thats what is causing it to run so crappy. looks like the poor truck is gonna sit at my work for a LONG time until I can afford a motor. time for the corvette engine!!

 

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How do you tell if the timming has jumped? I have one that has the exact same problem.

[bigred91]

you put a socket on the crankshaft pulley in front of the harmonic balancer. the distributor rotor should start to turn just as you turn the motor. i could turn my motor like 1/4 turn before the rotor started to turn. that shows that there is a lot of slack in the timing chain.

[ratchet]

replacing the timing chain on that truck is cheap an easy. How many miles are on it? If it's well over 200k than the motor is probably just plain wore out.

[95Sierra2500]

It takes all of about an hour to change a timing chain on a TBI 350. It's simple and straightforward.

1. drain radiator

2. remove fan shroud/fan/belts/water pump AND pulley

3. remove harmonic balancer

4. remove timing cover

5. remove old timing chain, install new one (remember to line up your dots!!!)

6. reassemble in reverse order and start truck!

 

there may be some little steps that i'm missing, but this is pretty much it.

[bigred91]

it has about 220k on it. the only thing is, I cant afford a new engine. I am gonna fix it the easiest/cheapest way. then sellin the truck. hate to do it but thats my cheap side coming into play. had the truck since i was 16 so need something different.

[citydriver]

I have a tbi 350 in my 1991 chevy. It will practically not even start when its really cold out. it fires up then dies right away after like 2 seconds of idling.  Also when driving at highway speeds and i punch it, it falls on its face and basically looses all power. I have replaced the distributor, reset the timing at 0, cap, rotor, plugs, wires, iac, coil, tps, basically every module on the motor. any info is helpful guys. thanks

 

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Anybody put a vacuum gauge on the engine. should read from 15-20in hg at idle. Then snap to 0 then back when throttle is goosed. If the timing chain jumped a tooth,the engine may not even reach highway speeds, or even start at all. It may be possible that there is an exhaust restriction(clogged catalytic converter) or a faulty EGR valve. Any vacuum leaks at the TBI unit base gasket. Just a few things I would also check.

 

p.s. A bad Coolant Temp. Sensor(near the thermostat housing in the manifold w/2 wires,usually 1 yellow and 1 black) would cause a full rich condition. Causing a cold start problem and some similar symptoms that you described. Running that way for awhile would also have an effect on the Oxygen sensor and Cat.converter. Not a bad idea to replace the Temp sensor when you change the coolant, just a thought for others reading this. $14-16 is cheap compared to the problems it creates....just my $.02