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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: DuckAholic1 on January 25, 2015, 04:29:27 pm

Title: TBI running rich...Help!!
Post by: DuckAholic1 on January 25, 2015, 04:29:27 pm: Any suggestions? 87 5.7 TBI rinning rich! Looked for vacuum leaks, none found. Timing set perfect. Spray from injecters look good(no dripping). Recent Throttlebody rebuild. What am I missing? Need your knowledge!!! Thank you!!
Title: Re: TBI running rich...Help!!
Post by: SLUG on January 25, 2015, 05:47:01 pm: I would check O2 sensor. Do you still have factory exhaust?
Title: Re: TBI running rich...Help!!
Post by: DuckAholic1 on January 25, 2015, 05:49:08 pm: Flow master exhaust. No headers.
Title: Re: TBI running rich...Help!!
Post by: 78BIG-TEN on January 25, 2015, 06:08:41 pm: Check vacuum leak or the vacuum line from back of tb to map sensor or possible bad map
Title: Re: TBI running rich...Help!!
Post by: DnStClr on January 25, 2015, 10:10:21 pm: Your troubleshooting can be made easier by looking for codes thrown by the ecm. Did you check for codes? As suggested by slug, the O2 sensor is a possibility and so is the throttle position sensor, coolant temp sensor, timing too advanced, ===all kinds of possibilities. :-[
check them codes.
Title: Re: TBI running rich...Help!!
Post by: Irish_Alley on January 26, 2015, 01:02:15 am: cts is a good start i did a write up about how to test them
TBI sensors and testing (http://forum.73-87chevytrucks.com/smforum/index.php?topic=29996.0)
Obd1 code retrieval and decoding (http://forum.73-87chevytrucks.com/smforum/index.php?topic=29949.0)
1987 manual (http://www.73-87chevytrucks.com/techinfo/7387CKMans//Service/ST_330_87_1987_Chevrolet_Light_Duty_Truck_Service_Manual.pdf)
1973-87(91) GM Pickup Manuals (http://forum.73-87chevytrucks.com/smforum/index.php?topic=30115.0)
Title: Re: TBI running rich...Help!!
Post by: Captkaos on January 26, 2015, 07:18:47 pm: Get the codes and posted them or look at Irish's posts and follow them.
Title: Re: TBI running rich...Help!!
Post by: DuckAholic1 on January 26, 2015, 08:10:55 pm: Thanks everyone, will be checking codes in the A.M. Will post what I find. Wish me luck concidering it's my first time doing such!
Title: Re: TBI running rich...Help!!
Post by: DnStClr on January 29, 2015, 10:40:21 pm: You rebuilt the throttle body- did the kit include a new fuel pressure regulator? A weak spring there can be a cause of too much fuel.