I have a 1989 s10 pickup 2wd 2.5 l The truck sometimes stumbles during acceleration and stalls during deceleration. Ive changed cap, plugs, wires, tps sensor, injector, iac motor, fuel and air filters, removed egr valve and throttle body and cleaned carbon but there was very little. Ive checked for vacume leaks and havent found any. Ive done a compression check all checks good. After it stalls the truck starts right back up, so i dunno where to go next.
This truck has throttle body injection? If so, get a timing light. Connect it to any plug wire. Start the engine, and in the dark, point the timing light at the injector inside the throttle body. The fuel spray should be in a conical shape. If you see drops of fuel or missing fuel spray from the cone of fuel, you need a fuel injector.
Ive already replaced the injector no diffrence.
How about the fuel pressure regulator?
havent tried that yet I thought about that or fuel pump going bad but I have no way to adapt my gauge to check it or maybe even a hall effect switch im not sure
Just remove the screws for the top plate on the throttle body, and inspect the diaphram for the fuel pressure regulator for leaks.
na took it apart diaphram looks new
Okay. Here’s one thing to try. Since this an OBDI engine management system, you can unplug sensors and the engine management system will go into a default mode. This means for example if there’s a problem the engine coolant sensor for the computer, if it’s unplugged the engine management system will go to a condition that will allow the engine to run, and if there’s problem with that circuit the engine should run better because it goes into that default mode. This will cause the Check Engine light to come on, but these codes can be errased just by disconnecting the negative battery cable for 15 seconds.
So I would start unplugging sensors on this OBDI system, and see if unplugging one makes the engine run better.