I have an '89 RS 5.0 305 that I bought for $800 thinking it only needed distributor work. Car turns and stays on if continous flow of gas is poured into the injectors manually but shuts off as soon as I release the gas pedal to resume at idle. Fuel pump is functional and lines are clean. Check engine light is on. Any help or suggestions would be greatly appreciated. Anyone know where I can start? Or check? Or do?!!! Always loved 3rd Gens

 

my first thought is to check the IAC, pull it off, clean it up, i wana say if you turn the car over or have someone start it with it out you should be able to see the needle move

 

flash the codes for the check engine (use search feature if you don't know how)

how do you know the pump is good and the lines are clean?

What were the results when you checked with a pressure gauge????

 

Well, I removed the IACV this morning and it looks gunked up. Also I read something about the pintle not to stick out further than 28mm. Mine seemed way too far out and upon removal I noticed there was no gasket between the IACV and the housing for it. I hadn't checked the pressure on the fuel pump but it spit out a significant amont from the front lines when the lines were disconnected at the front end of the car and the gas pedal was pressed. Nor do I have a pressure meter. Will get one to test it to make sure. How do I know if my IACV needs to be replaced? Would not having the O ring make a difference? Thanks again guys. I've learned so much already thanks to you.

 

i know you can check it electrically by seeing how many volts or somethin that it puts out, ive never been good with the whole electric area so maybe some other guys can help ya there. Ive always been the type to just replace it and if the problem still exists i either leave it on cause a new part never hurts, or advance auto has never given me trouble about returning a part if it didnt fix my problem. A new one from them is about $36

 

I had the 305 tbi with the same problem mine would turn on for 5-10 sec then would shut off . I got the fuel pump changed and the ignition control module was not working so i got that changed also. After the car started right up and stayed on and run really good.
So you said the fuel pump is working so I would check the icm

 

The car is on jacks and I have to keep my foot on the gas pedal in order to keep the engine running. The very second I release the pedal, the motor dies. Are these tell tale signs of a bad IACV or a bad ECM?

 

pull the throttle body off and spray it down with alot of carb cleaner and put it all back together and run some sea foam through the tank and the PCV vavle. Def check the engine light code and if it still dies change the IAC valve.