1989 5.0 stalling

[IceIceBaby]

I have a 1989 mustang 5.0. When it is idleing it is usually around 500 RPMs but now if i don't watch my tach it will gradually go to lower and lower RPMs. It will do this for a couple of minutes and then finally die. It has a new fuel pump and spark plugs. I don't know what the hell it is and it sucks because I can't use my A/C or it will die even quicker. Just wondering if anyone could give me any ideas.....

[Deuce Is Wild]

Clean your salt and pepper shakers. Maybe freshen your ignition (not just your plugs) or clean your injectors. What is your voltage at the power supply points from the battery AT the ignition, ECU? Did you check the impedance of the injectors?

Fortunatly if you tried all this, 5.0's are plentiful and you can just go out and get a ECU and try replacing that.

[GTStang]

Originally Posted by IceIceBaby

I have a 1989 mustang 5.0. When it is idleing it is usually around 500 RPMs but now if i don't watch my tach it will gradually go to lower and lower RPMs. It will do this for a couple of minutes and then finally die. It has a new fuel pump and spark plugs. I don't know what the hell it is and it sucks because I can't use my A/C or it will die even quicker. Just wondering if anyone could give me any ideas.....

Let me guess...... did you put in a bigger than stock fuel pump?

[Deuce Is Wild]

Originally Posted by GTStang

Let me guess...... did you put in a bigger than stock fuel pump?

I put in a 190LPH when I was still stock and didn't have any problems...

[williamskinner16]

I had a 1991 Explorer, it had a similar problem. Try pulling your IAC valve located ahead of your intake plenum and spray it with injection cleaner or replace it. Im not saying Im sure, but cleaning it might fix the problem. I hope this helps.

[GTStang]

Originally Posted by Deuce Is Wild

I put in a 190LPH when I was still stock and didn't have any problems...

Not all Stangs 5.0 after minimium 12years in his case 16 year
s are equal.

Understand a 5.0 stock charging system is barely adequate off the assembly line. Add in 12 years and 100,000+miles of wear and tear and it's good chances it has become less than adequate.

So just cause yours was fine doesn't mean his is. Many people have had issues adding a bigger fuel pump cause they draw more current.

[Deuce Is Wild]

Originally Posted by GTStang

Not all Stangs 5.0 after minimium 12years in his case 16 year
s are equal.

Understand a 5.0 stock charging system is barely adequate off the assembly line. Add in 12 years and 100,000+miles of wear and tear and it's good chances it has become less than adequate.

So just cause yours was fine doesn't mean his is. Many people have had issues adding a bigger fuel pump cause they draw more current.

Yeah, and my '89 GT had 32 miles on it when I replaced the pump.