Well, I am a little confused because I can't find a 1997 5.7 TFI spec in my Chilton's manual. It says they are all MFI. I'm going to proceed with TFI info but you should make sure what you have there. A TFI will have a carburator style air cleaner and the injectors (2 of them) are mounted in a throttle body that looks like a carburator. MFI systems will have a "runner" style manifold and a horizontal throttle body with a 4 or 5 inch "tube" feeding the air to it.
When you prime the throttle body, is it running relatively smoothly? I am assuming you are using very little fuel when doing this. This indicates a fuel delivery problem and you seem to have addressed everything but the injectors. One thing you can do is check to see if any fuel is being delivered into the TB (TFI)when you open the throttle manualy. With the key in the run position (you should hear the fuel pump pressurize the fuel lines/rail) and the air cleaner removed, look into the top of the TB and have a friend press the gas pedal to the floor or operate the linkage yourself under the hood. (Wear safety glasses.) Are you hearing the injectors spray and smelling the fuel and or seeing it delivered down the throat. Don't try to crank the engine over while your face is over the TB. In the case of a backfire flame can shoot back out of the top of it and burn you. I'm starting to think your injectors are plugged up or the electrical circuit to the injectors has a fault. A little more back story on the recent history of this vehicle may be helpful. I assume you have checked and rechecked all the fuses etc relating to the fuel system. If not, do that for sure. The function of all fuses is printed on the cover if you are unsure. If the system is a MFI system, you need to get a noid light and check the injectors. Some major auto parts stores have htese for "loan" and many will help you with how to run the test. Hope this helps but I'm not really sure we have the details right so please check to be sure before trying to use this advice.
Tuesday, September 21st, 2010 AT 10:39 PM