'89 Formula Firebird 305 TBI. New fuel filter, new injectors and fresh fuel.

It will do its' everlovin' BEST to start....but won't quite do it.(occasional pretty backfire through the carb, as well! ) The injectors are working, but they seem intermitant...sometimes they seem to spray nicely and other times its' almost a drizzle.

There's no pre-start injection, so I'm confused.(my past '84 'Bird and the present '89 Grand Am do this)

Weak fuel pump, maybe? Need breather on car to sense airflow(***, I hope! )

I'm not well versed in these cars, so bare with me!

NM

 

I don't recall my TBI ever spraying anything during the priming of the fuel system. It just pretty much gets the system under pressure then when cranking sprays in noticable intervals.

If it was continuous during start, there is a potential for the IAC tubes to become flooded as that's the only way air/fuel gets in during a normal crank.

Backfire through the throttle body indicates that something is not working right. Air comes in, its sparked/ignited then it has to be exhausted. Now if your cat was clogged, this will do that. Also if your valves aren't opening properly then your not exhausting the gasses properly and it can only go back through the intake.

You have backfire, so you have fuel and ignition working somewhat, you have to ensure that next the airflow is unobstructed, and usually a clogged cat does occur after some years.

 

did you have the distributor out? could be a timing problem...

 

Distributor has never been out, and the cat is long gone(gotta' love Alabama emissions regs!)

Got it to actually run a bit on its' own this afternoon. Still a bit of backfire, but I figure it ain't run in a long while so I'll blame that on lifters and sticky valves.

Still won't idle....at all. Won't keep running at any throttle setting and the spray still seems intermittant.

One other quik observation. As the battery wears down and cranking RPM fades, the spray gets steady.....it stops if the motor is tuning too fast.....I'm lost!!!!

Back outside to play, now. If anyone has an idea, let me know!

Thanks

NM

 

Your distributor needs serious adjustment. Check your timing and be sure the tan/black wire is disconnected when you adjust it.
Your timing is way off.

 

You could also have had the timing chain jump a tooth or two. If it has too much slack they can do that. Had it happen before on a high mileage engine. Granted, I am a bit of a pessimist.

 

HHHMMMM.....not knowing much about this, I didn't think of timing as a problem.

After several comments here about timing I checked the distributor.......someone, at some time, has loosened it!

Guess its' time to pull out the Haynes manual and figure out how to get it CLOSE to a proper timing! At least close enough to correct to get it to run so I can set it correctly!

Thanks, folks!

NM