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94 GMC 305 TBI code 45

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Old March 13th, 2021, 7:58 AM
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Default 94 GMC 305 TBI code 45

Need some assistance. Recently check engine popped on with codes 35 and 45, some of the symptoms I’ve noticed is getting slight skip at idle every couple of minutes and temp gauge fluctuation. Once the gauge reads about 205/210 it will suddenly drop to about 170 and stay there, seems anytime it gets to that temp it will drop(heat works great never overheats).

I replaced the IAC for code 35 the plugs, cap rotor and wires are new. With 45 still present can the gauge fluctuation I am seeing can this be related, believe 45 was 02 sensor sensing a rich reading? Read somewhere the engine temp sensor next to the thermostat could throw things off. I also have pretty loud injectors, can hear them in the cab.

Noticed when I had the hood open what I believe is a canister . Someone used electrical tape to try and fix a hose- what is this canister can this line cause problems? Thank you

Last edited by Danny John; March 13th, 2021 at 8:01 AM.
Old March 14th, 2021, 7:10 AM
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The black round canister is your evaporative carbon canister. It collects gasoline fumes from your gasoline tank and stores them until the motor is running. The hose/or plastic conduit is your purge hose, which usually goes to a device, a Vapor Canister Purge Valve / Solenoid, that only allows the gasoline fumes to be sent to your TBI unit under the proper conditions.to be burned up by the engine. Were I you I'd replace that hose/conduit. It should not cost much to do so. The newer evaporative units are much more complicated than yours, which is an older unit.

As far as your coolant fluctuation issue, I'd make sure that all the air is out of the system first. If your fuel injectors are making noise, you can buy rebuilt ones for $30 with a core charge too. Might want to put a new fuel filter on your Chevy too.

GM OBD I code 45 means your left bank is running too rich:
  • Faulty O2 sensor
  • Leaking fuel injector or fuel pressure regulator
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Old March 14th, 2021, 10:50 AM
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Originally Posted by oilcanhenry
The black round canister is your evaporative carbon canister. It collects gasoline fumes from your gasoline tank and stores them until the motor is running. The hose/or plastic conduit is your purge hose, which usually goes to a device, a Vapor Canister Purge Valve / Solenoid, that only allows the gasoline fumes to be sent to your TBI unit under the proper conditions.to be burned up by the engine. Were I you I'd replace that hose/conduit. It should not cost much to do so. The newer evaporative units are much more complicated than yours, which is an older unit.

As far as your coolant fluctuation issue, I'd make sure that all the air is out of the system first. If your fuel injectors are making noise, you can buy rebuilt ones for $30 with a core charge too. Might want to put a new fuel filter on your Chevy too.

GM OBD I code 45 means your left bank is running too rich:
  • Faulty O2 sensor
  • Leaking fuel injector or fuel pressure regulator
Thanks, looks like by condition of injectors and regulator along with gaskets are new.

I am having trouble finding just the plastic line?
Old March 14th, 2021, 11:00 AM
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That line is called "Synflex". It is gasoline and oil resistant and places like NAPA should be able to fix you up with an insert to install between the two pieces when you cut out the damaged part. Looks like 3/8 diameter tubing.
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Old March 14th, 2021, 2:52 PM
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Originally Posted by hanky
That line is called "Synflex". It is gasoline and oil resistant and places like NAPA should be able to fix you up with an insert to install between the two pieces when you cut out the damaged part. Looks like 3/8 diameter tubing.
thanks I’ll do that!
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