TBI running rich

[BobbyBigRigger]

I just got a 1990 5.7 TBI running after 10 years of sitting inside. I did a rebuild of motor, cleaned gas tank, new pump and sending unit and new filter. Also new Coolant sensors, oil pressure sending unit. I put long tube headers on it, have it timed. The issue I seem to have is its running rich, loads up with gas and stalls out. Once I do have it running and throttle to higher RPMS, it seems to mellow out. But once I shut it off it wont restart as if its flooded. Leave it sit until drys out, fires right up. Any ideas where to start?

 

[scott2093]

Any ideas where to start?

A scanner that can look at data stream might be able to point to something obviously wrong. Have you tried pulling any codes via aldl? May get lucky.
Fuel pressure test...
Did you rebuild tbi? Regulator...?

I don't see the emissions manual for your year. Maybe it's hidden somewhere in the sticky somewhere but you can probably download the 89 or 91 emissions manual and go through some of the driveabilty troubleshooting until someone else chimes in....

88-98 Service Manuals

Over the years I have collected a bunch of GM service literature. Links to PDF Scans of service and STG manuals and a links to the Parts manuals. You'll need the FREE Adobe Acrobat reader to open these files. Get it directly from Adobe here {http://get.adobe.com/reader/} If you're not...

www.gmt400.com

 

[95burban]

Did you replace the o2 sensor?

 

[BobbyBigRigger]

I actually have the O2 sensor unplugged. Did not put a bung in the Header.

 

[BobbyBigRigger]

I will be putting a scanner to it. Now I'm thinking that's my issue is that the O2 sensor unplugged. I see Summit sells bung adapters for the Headman Headers

 

[termite]

My first thought would be a fuel leak if its flooding itself out (injectors leaking, perhaps incorrect injectors?).

I believe there is a clear flood mode in the FSM. Don't recall the specifics but had something to do with flooring it while cranking? Can likely be found by searching the FSM or even on here.

Without the O2 sensor feedback, it will stay in open loop and run off of the preset tables in the tune/ecm. Correct ecm and chip for the application?

Someone will be along in the next few days (or sooner) asking for the information from an actual scantool, not just code reader.

 

[GoToGuy]

The 90 manual is only one book , check index, fuel emissions are in there. Open it up. Remember manuals get bigger every year.

 

[BobbyBigRigger]

Map 4.67 reading, 02 sensor in open loop. .57 for TPS.

 

[GoToGuy]

The throttle position sensor functions similar to a volume knob. Low volume= low voltage, high volume, wide open, = higher voltage. Throttle at idle, engine off, watch voltage as you increase throttle, smooth voltage increase with throttle, no dead spots.
Is the O2 voltage fixed or is it adjusting up and down , like it's alive, not lazy or dead?
Are the injector sprays an even umbrella, cone shape, no dribbling drooling fuel drops?

 

[BobbyBigRigger]

The throttle position sensor functions similar to a volume knob. Low volume= low voltage, high volume, wide open, = higher voltage. Throttle at idle, engine off, watch voltage as you increase throttle, smooth voltage increase with throttle, no dead spots.
Is the O2 voltage fixed or is it adjusting up and down , like it's alive, not lazy or dead?
Are the injector sprays an even umbrella, cone shape, no dribbling drooling fuel drops?

The injectors are spraying evenly, no drips, or streams. The O2 sensor currently is unplugged. 1 wire sensor that should be bunged into the header. Thought was to hook a sensor to it and close the loop on it? Would this open loop cause the ECM to make the injectors run rich?