tbi running rich

[rusty but trusty]

the truck is a 87 v1500 with a 305 but originally a 350 and i have replaced o2 and the temp sensor with 2 wires but it is still getting the bumper "sooty" any ideas

[Townsend600]

mine is doing the same thing.  I tried spraying wd-40 all around up top and found no vacuum leaks, replaced the coolant temp sensor and checking timing (with ECU unplugged)  also checked all the plugs and wires.  Everything looks good but I have a slight low end miss and it's runnning fat on the bottom end.  I am seriously considering swapping over to a carb.  I don't care much for this early TBI system. 

[DnStClr]

 There are a bunch of possibilities. Any other symptoms? Such as-is it hesitating, or backfiring, or not enough power?
The cat. converter could be partially plugged, the injectors could be allowing too much fuel into the throttle body, spark plugs could be fouled, ignition timing could be off,  there could be a low airflow to the radiator, compression could be low, IAC motor could be faulty,...
One of the first things I like to do on my 87 is to look for fault codes from the ecm. Do you know the procedure? There are posts describing how to check for code faults. A search should bring a few of em up.

[rusty but trusty]

i removed the cat long ago i should have mentioned it and the computer timing is disabled maxing advance at 4 degrees the computer made it not run at all but the timing is set to 0 at idle and the power is not enough to break the tires loose ever

[Townsend600]

same here.  Replaced the CTS and have checked timing. Plugs are all new as well with a new dist.  I hate to start throwing parts at it but I guess I'm going to put a map sensor on it first and if that doesn't work replace the IAC.  I will prob do a compression check on all 8 first though. 

[rusty but trusty]

timing has been checked and compression is 175 and at most 10 psi off

[bd]

...I tried spraying wd-40 all around up top and found no vacuum leaks ... I have a slight low end miss and it's running fat on the bottom end.

Towsend600 - WD-40 doesn't work well for finding vacuum leaks.  Try using Berrymans B12 or something similar.  Did you check your spark plugs, wires, cap and rotor?

...the computer timing is disabled maxing advance at 4 degrees the computer made it not run at all but the timing is set to 0 at idle and the power is not enough to break the tires loose ever

rusty but trusty - Not surprising if EST has been defeated - fuel mileage is probably in the toilet, as well.  Did you set base timing to 0° with EST in bypass mode, or have you since migrated to a mechanical distributor?   

There are a bunch of possibilities.  Any other symptoms?  Such as-is it hesitating, or backfiring, or not enough power?
...look for fault codes from the ecm....

To both - Did you do this ^^^^^^ ?  Also, with the engine OFF and air cleaner removed, use a clean rag to wipe off the spray nozzles of both injectors.  Then cycle the key ON/OFF several times w/o cranking the motor.  Check the injector spray nozzles with your finger.  They should be dry - if not, replace the injectors.  You should measure fuel pressure, as well.

FYI - Unless the motor is having trouble controlling idle, I don't think replacing the IAC will benefit your solution(s).

[rusty but trusty]

when i leave the est hooked up it runs horrible never mind thats a understatment
 but it stalls at idle always and must be floored to start

[Captkaos]

Are the trucks still Fuel injected?  You don't need to give it any gas to get one started. 

[rusty but trusty]

yes it is still fuel injected but to even get a pop or bang or anything other that a hot starter the pedal had to be played with but with the est disconnected it runs decent just very low power and lots of soot on bumper

[Captkaos]

Did you swap out the ECM controlled Distributor?  Drivability is going to suffer if you have the same one.  How many miles on the motor?  What codes are getting thrown?  Have you checked fuel pressure?  All the throttle does on a TBI motor is add more air, it doesn't do anything with gas short of the throttle reference for the ECM and in cranking you don't need to open the throttle.

[bd]

Adding to the above ^^^^ post, the TBI system has a "Clear Flood" feature that forces lean fuel mixture while cranking at WOT in the event that an engine initially floods.

[rusty but trusty]

would it be a good idea to use a mechanical distributor?
the service engine soon light is on but sometimes if i reely get on it the light goes out for a couple of minutes. the cts is working it changes resistance with temperature.
also i looked for posts how to read fault codes and couldn't find any, any tips where to look?

[Townsend600]

if you go to a mechanical dist. the ECU is going to go nuts.  Truck should be at or close to 0 degrees timing when bypassed.   

[Captkaos]

My opinion is you need to hook everything back up correctly with the TBI system intact clear all the codes and start from base one with the EST disconnected set timing to 0 and plug it back in and read the codes.  If it stays on you have issues.

To pull the codes, put a paper clip in the A and B terminals of the ALDL connector (top right 2 slots) turn the key to the on (not run) position and count the flashes.  It will ALWAYS flash the codes 3 times and the first code is ALWAYS 12 ( flash.........  flash..flash)  Any autoparts store can pull the codes for you also.