1991 GMC s10 Sonoma 4.3 L Started running rough on freeway at 80 mph and shut down. On cold start it will run for about four minutes then rough idles and shuts off. Will sometimes restart, but most the time need to sit for a few hours before restarting. Replaced fuel pump, fuel filter and “Icm” ignition control module.. have changed the fuel, check the air filter and inside the throttle body, and cleaned throttlebody and injectors with carburetor cleaner. Runs good for the first three minutes, then has issues rough idles, and then shuts off.
Is the measured fuel pressure good now?
The cat might be failed on a 30yo truck. Take out the O2 sensor #1 and see if runs any better.
rough idles,
thoroughly test for vacuum leaks. Find a loaner smoke machine.
Those are notorious for having fuel injection problems. First check the fuel pump. It could be going out, but if not I'll have plastic crap on the fuel injection system off and we'll go bad and then they'll do exactly that
they're not really injectors. Technically they're called poppet valves. Part of the "spider" assembly which was flawed, and updated by GM so look into that. Intake manifold leaks are also common so check for that. If the gasket is original you'll want to get rid of it and replace with a metal one.
I replaced the fuel pump, rebuilt the throttlebody with new fuel injectors replaced plugs, wires and coil and ICM still having the same problem
I replaced the fuel pump, rebuilt the throttlebody with new fuel injectors replaced plugs, wires and coil and ICM still having the same problem
Did you upgrade the central injection system to the updated multi-port injection system like I mentioned?
This is the GM bulletin:
https://www.tsbsearch.com/Chevrolet/00-06-04-003B
installation instructions: http://chevygmcvans.com/viewtopic.php?t=69
video:
https://www.youtube.com/watch?v=LrPrPUgNLf0