Question about 1990 Chevrolet C1500
I have a 1990 c1500 with a 4.3 vin. z motor and a th400 trans. I rebuilt the throttle body 6 months ago and it has been running rich for the last month. I am getting 6-8 mpg. It has a msd system with a hypertech chip and cold air intake. I put the factory items back on and still the same problem. The fuel pressure is good ang the o2 is new and i am going to replace the temp sensor soon. Did I rebuild the tbi wrong or is it somthing else?
I recommend you check the fuel pressure regulator diaphragm for proper installation and tears. Did you get a new one with your rebuild kit?
Posted on Jul 01, 2017
Please go to the crossfire injection forum to get some straight answers to the 82 corvette CFI system and how to troubleshoot it properly. There's a lot of misinformation given here, so much so, I don't know where to begin.
One thing is, the 82 corvette CFI does NOT have a MassAir Flow sensor system, it uses MAP and O2 mostly. The CTS sends a signal to the ECM telling it what the temp of the motor is and in turn the ECM controls the amount of fuel being dumped. On the older (orignal) CTS sensors, they have one wire and takes its ground from the threads. If any coorosion takes place, usually the CTS will report a cold engine and request lots of fuel.
To repair this issue, install one of the newer style CTS sensors that have two wires, one for signal and the other is ground.
Fuel pressure and vacuum leaks on any CFI motor play key roles. Set the FP to 14-15psi measured inbetween the TBs. The regulator is located on the rear TB and must be slightly moded to make it adjustable and can be done in a few minutes.
Posted on Mar 07, 2009
That eliminates the crankshaft and camshaft position sensors. Have you checked the fuel injector itself for an open winding or stuck valve plunger? There should not be a steady 12 volts to the injector--if good injector, it would be spraying fuel steadily into the throttle body. But at least the engine should try to run if poorly. Take the injector out, dry it off with air, and intermittently apply 12 volts to one terminal while grounding the other. You should hear a click from inside every time you touch 12 volts. If not, replace it. If it does, it may be plugged with debris. Try blowing through it in reverse with compressed air.
Posted on Jul 17, 2009
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