I have a problem with my truck starting, chevy 1990 throttle body type 2 top injectors. It takes several cranks to start if it even starts at all without flooding the engine. _ having this problem before I had replaced the throttlebody, injectors, wires, spark plugs> after that it just kept flooding - taking it to my mechanic he reset the computer. Is this a major computer issue and not a injector issue ?

Suggest you have injector balance test done , leaking fuel injectors , maybe .

Do the injectors flood if they are unplugged ?

If you have a choke on a 1990 1500 ,something is really wrong.I have never seen a choke on a throttle body.If you don`t have fuel check your fuel pump.

First I am not aware of two flaps or throttle plates in the body, but I do see a rubber diaphram with a rod that could open a plate with vac.
If you have something blocking air entering the throttle body it could cause the engine to flood. A faulty temp sensor could also be telling the computer to dump extra fuel into the cylinders, but you should have a trouble code for that.
If the plugs are getting spark the ignition system is working.
What would happen if you disabled the fuel pump and started it without extra fuel ? You could have a leaking fuel pressure regulator or something allowing extra fuel into the cylinders.

Leak in fuel line. Put air pressure gauge on rail and crank engine. Should get psi reading. There should be a nipple on fuel rail for testing. If no pressure check for leak

You have fuel at the rail, now it's time to see if it's making it past the injectors. Disconnect the air intake duct from the throttle body. Have an assistant crank the engine over while opening the throttle slightly. Spray starting fluid into the throttle body and see if the engine attempts to start. If it does, then the injectors are not firing. The reason the injectors are not firing could be :
1. Blown injector fuse (sometimes marked "INJ").
2. Bad crank sensor.
3. No power to computer.
4. Computer problem (bad injector drivers).
If you have tried to start the vehicle many times, then you should start to smell fuel if it is getting into the engine. If you smell fuel, then let it sit for a while and try checking for spark. An inexpensive spark tester can be purchased from most parts stores. The reason for no spark could be :
1. Blown ignition fuse (sometimes marked "IGN").
2. Failed ignition module.
3. bad crank sensor.
4. bad ignition switch.
If everything checks out, then try disconnecting the battery for at least 20min. the longer the better. If the engine still wont start, then more advanced diagnostics will be needed to determine the problem. I hope that this information is helpful and thank you for using Fixya.com.
WARNING : Wear safety glasses when performing the starting fluid test. Keep hands and loose clothing away from moving engine parts and cooling fan motor. Use caution when working around distributorless ignition systems. These systems produce extremely high voltages which can cause severe injury or even death.

Sounds like you have an injector leaking. Have someone just cycle the key on and off to run the fuel pump but don't crank the engine. If you see fuel dripping from the injectors, unbolt the injector cover on the throttle body, remove the injectors and replace the orings around the injectors.

If you pull the aircleaner off and watch the throttle body injectors they dont have anything coming out?
Double check the map sensor and the throttle position sensor?
Computer? I wonder if a wire to the computer has shorted out to ground.

timing? if you've got gas and you've got spark, have you checked the crank/cam shaft position sensors? have you put a timing light on it to see if you might have jumpped timing?

you may have a low fuel pressure problem or it may just need new plugs IE. a tune up