Dies as soon as i let off the gas!
 

I have a 91' blazer full size with 5.7l tbi. it will be easier 2 say what i haven't done, cuz i'm pretty deep with both time, and $ in this thing. it died on me @ a stop light 3 weeks ago, and has only ran 2x since. it will not start unless i stay on the gas peddle, and dies immediately when i let off. i have replaced the fuel pump, and filter, and the entire ignition. help me please!
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Re: Dies as soon as i let off the gas!
 

TBI is not my thing, but the TPS and IAC sensors commonly have issues. That might help you start Googling. Check out fullsizechevy.com and 73-87chevy.com (CaptainFab over there knows his TBI).

Oh, and welcome!

Re: Dies as soon as i let off the gas!
 

thank u. i have replaced the iac,tps,cts,oil press sending unit, and the map sensor. they were all fairly innexpensive, and i wasn't overly confident with my testing. the oil press was failing 4 awhile, and when i replaced the ign. module, and pick up coil i had 2 have the distributer out and that gave me easy access to that unit. i also have changed the ign. coil,plugs,cap, and rotor. i have good spray pattern from the injectors, and plenty of pressure from the fuel pump, that i had 2 replace about 6 months ago. i'll check out the other forums also. and again thanks for the advice.
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Re: Dies as soon as i let off the gas!
 

When you start it up and are on the gas, how does the engine act? As in will it idle smooth at a higher rpm while giving it a gas? I was going to say that you should check the ignition coil and the pick up coil but it looks like you've already replaced that!

Re: Dies as soon as i let off the gas!
 

Maybe a vaccuum leak?

My 307 2bbl acted the same way, a vac line came undone and was sucking air.

Re: Dies as soon as i let off the gas!
 

Oooh, thought of something else. The timing advance is run through the computer, there is a brown/white wire that enters the firewall down low on the driver's side, like below the brake booster. If you don't disconnect that whenever you're working on ignition stuff you will blow the 10a fuse and the truck will remain at 0 degrees through all RPM. Check the fuse.

Re: Dies as soon as i let off the gas!
 

exactly what i was thinking, keep it running at a constant rpm as possible and spray brake cleaner on the intake where it mates to the heads and the ends and see if the rpm changes

Re: Dies as soon as i let off the gas!
 

Years ago I had an '89 S10 that was having similar issues and it kept throwing out trouble codes. I fixed or replaced the majority of the parts that you had, until it was determined that the computer was fried, not allowing the engine to run properly, hence the trouble codes. Put a new computer in and all the problems went away. Just a thought......