atokatim

Hello all again! I have a strange problem I am trying to get fixed. My 1990 S10 2.5L has a hard time getting started in the morning or when it is cold outside. I have already replaced the coolant temp sensor on the T-stat housing which made no difference and checked the wires for resistance from the sensor to the ECU which showed 4.97k. When I unplugged the ECU, the resistance was none. I also checked to see if either wire was grounded out and neither were. I have also replaced the O2 sensor, Distributor cap, Button, spark plugs, and wires. Other diagnostics I have done are disconnecting the MAP sensor when running. This did make the engine run different. I also unplugged the TPS which did not make the engine run different, and I unplugged the IAC valve which did not make a difference. It sounds to me like the ECU is in LIMP mode. Every once in awhile, I will get a SES light and the code is a 43 I think. It had something to do with the ignition module. The light will stay on for about 20 seconds to a minute, then turn off. The engine does not run any different when this happens. As for how the engine starts in the cold / morning... It takes about 5 minutes to get it started. The first 10 to 30 seconds is nothing but cranking with no ignition at all. There is fuel, and there is spark. If I pump the gas a little, the engine will sputter for a second, but not start. Once it sputters, I can press the gas again and sometimes it will backfire from the intake and ignite a fire in the TB. I have checked the mechanical timing which is spot on and the electrical timing is set at 8 degrees BTDC as stated in the manual. Once the sputtering / backfire begins, it takes about 10 more seconds with about 1/4 throttle to get the engine started. After the engine is started, it runs really rough and smells very rich. Even after the engine is at normal operating temperature, the engine runs very rich. Once everything is fully warmed up, I can bump the key for 1 second and the engine will crank right up. It still runs rich though. Can someone help me get this diagnosed and fixed? The truck is only getting 16 mpg which sucks!

atokatim

Anyone? I really need to get this truck running better!

atokatim

This forum must be dead. No replies in a week.

ritter18252

Have you ever found the problem. I joined this page today so I can reply. Thank you