Hey everyone, I’ve got the same problem here. I recently acquired an 86 and a few years ago I got an 88. Both have the 2.5 TBI. The 86 is a longbed, 5-speed 4WD. 88 is a shortbed 5-speed 2WD. My 86 ran great but it lacked power, so a few weeks ago I was under it with a sawzall and the cat and muffler fell on me while I was just laying there!🤣🙄🤣
It then ran better than ever and had tons of power and averaged 26MPG. Last week it started losing power and running extremely rich and hesitated accelerating. I cleaned the injector, replaced the ECU from my 88 (which I know to be good), put the 88 fuel pump in it, and it made no difference except that it doesn’t hesitate to accelerate anymore. It starts up and runs great cold, but once it warms, it runs rich enough that it’s only getting 5MPG!🤬
MAP sensor is good (bought it new for the 88 last year before it became a parts-truck for mechanical failures), temp sensors check good, I know it has sufficient fuel pressure, and the injector is fine. How to I test the O2 sensor, or bypass the O2 sensor with a resistor?
