need help

91 b2200fi and what kind of problem do you get with a ecu going out becuse my truck run but with a lot of black smoke coming out of the tailpipe

black smoke mean running to rich ck fuel pressure and pressure regulator also see if any codes in computer also check o2 sensor and coolant temp sensor

if what bfg2200 says is all ok then if the ecu is suspected i would check you 5 volt reference signal from ecu i usually check at temp sensor not gauge driver on tstat housing the one under your intake rec looking at etm for correct pin