Any idea what would cause my 302 efi to stall at low rpms when it was warm?

I went to the store and when I came back out it would crank up then stall. I drove home but had to keep rpms over 1200 the whole way home to keep it from stalling.

 

Are you sure the EGR isn't stuck?

 

How would I check this?

 

The first thing I would is check for codes, or have someone with a scan tool check for you.

The engine light doesn't have to be on for codes to be stored.

 

Pulled codes 10,11, and 87. Does this mean I need a new fuel pump?

 

11 is a pass.
87, intermittent in the fuel pump wiring. ?

Is the fuel pressure regulator leaking? (fuel in hose?)
Can you check pressure at idle?

I am not too good with these EFI systems.
There are some very knowledgeable guys on this forum.

 

Also a dirty throttle body will cause lower rpm and hunting or stalling. Get a can of throttle body cleaner and an old toothbrush. With engine off spray around the TB and clean everything. Then start up engine and spray into TB while holding throttle open to prevent stalling. Last step, change the spark plugs.

 

May well be as simple as a vacuum leak.

 

A Code 87 means the computer thinks the fuel pump isn't getting (full) power when it should be.

I would use a volt meter to verify this... check for power at the relay, at the pump, check for shorts to power or to ground in the wiring, check the continuity of the wiring, check for corroded connections, etc. and go from there based on what is found.

 

I am so glad I still have a carb.

 

I drove around today just to see if I could get this problem to repeat itself. everything was fine until the motor got to normal operating temperature.

This leads me to believe that the ATS is bad. I replaced it 2 yrs ago though, shouldn't it last longer than 2 yrs?

 

What is an ATS?

 

I don't know what an ATS is but I want to explain something to you...

The information I'm giving you is coming straight from the Ford 1986 Powertrain/Emissions Diagnostics Manual, this is what the guys who designed that system gave to the dealers to use to diagnose problems:





You don't tell us in which of the three possible areas you get your Code 87, but I'm assuming you got it by doing a KOEO test, in which it says - for all engines except the 2.8L with the Feedback Carb - to go to Pinpoint Test J7:





J7 has you testing wires & relays and replacing the computer if all the items check out:






Now, the books are not perfect and it is conceivably possible you may run across something else in your diagnostic procedures that was causing the error to appear (this is more possible given the advanced age of your truck).

The book doesn't list something called an ATS as a contributing factor to an Error 87 in KOEO, I don't even know what that is.

But this is where the engineers who designed & built the system said to go looking for the source of the problem, so I'd begin there. You may have a bad battery connection, a dying relay, frayed or shorted wires, a defective alternator/regulator, you could even have a computer with leaking capacitors, or maybe something else.

But you are going to be better off doing some actual diagnosis and figuring out the problem than taking a shot in the dark and throwing parts at it.

 

I was referring to the air temperature sensor, however, the manual is a great resource and I will definitely test these things out! Thanks so much!

 

The factory manuals are a great resource - but many times you need the special (Ford) tools to complete the troubleshooting steps. Note in the above screen shot the reference to using a "breakout box". Most do-it-yourselfers will not have the tools. But the manuals get you close. So you may end up replacing a "working" part or two before you get it fixed. That's okay, and still cheaper than taking it to the shop, most of the time.