90 fullsize blazer with tbi350. All the sudden I have absolutely no power, barely idles and when it does its extremely rough. When it dies I have to give it some throttle to get it to start again. When it starts it blows a ton of black smoke and starts idleing extremely rough again. Any help will be greatly appreciated!

 

Anybody?? It started this morning but backfired a few times first. Idled for a few minutes really rough then died.

 

Black smoke is oil being burned by the engine, typically. Does it smoke for half a minute or so then clear up, or does it continue to smoke?

Typically if it smokes at start up and goes away it is worn valve guides. Could also be from improper a/f mixture.

you say so I would guess a vacuum hose right off the bat. Have you popped the hood to look and listen for an obvious leak?

Have you done any maintenance lately like changing spark plugs or adjusting the timing? Anything at all?

 

On the contrar black smoke is unburnt fuel ,blue smoke is oil,white smoke is water or coolant.

 

Well about three weeks ago I out a new timing set in it because it had gotten so worn and jumped a tooth. I also put new plugs and of course fixed the timing. I didn't find any major vacuum leaks either. After I replaced the timing set and plugs it ran ok though but things went downhill rapidly. It smokes black a lot at startup then it smokes on throttle. Exhaust seems to kinda pop some while applying throttle too. Thanks

 

I would guess your timing is off than.

 

Did you use a cam degree wheel to line up your timing gears?,was the cam replaced and With backfiring or popping Im going to say either you have a plug wire off on dis or the timing is still off.

 

You're right black is fuel, blue is smoke.

Did it ever run right after you replaced the timing set?

What did you gap the plugs to?
How did you set the timing? I'm new to TBI but have learned that there is a wire you need to disconnect and set the base timing to 0*.

And why did you have to set the timing? If you didn't remove the camshaft there is no reason to believe that it moved.

 

Since you described seeing black smoke, as previously mentioned, that is fuel. I'm just throwing it out there, but if I were you I would replace the coolant temperature sensor on the top of the intake next to the upper radiator hose. These go bad often, and when they do, the injectors dump way too much fuel down the TB and it will never run right. Even if this isn't the problem, it is still good to replace this sensor because the they go bad VERY often. They should be a common maintenance item.

 

Timing is set at 0° with the wire unplugged like its supposed to be. The gears are lined up by the dots on them and can was not replaced and all wires are correct. It ran ok just not much power right after I replaced the timing set and plugs are gapped to book specs. And the distributor was replaced a week before the timing set so I was just double checking that timing was correct.