I have a 93 aerostar 3.0 auto and have a problem starting it.
I replaced ignition module, coil, distributor cap and rotor but that didn't fix the problem so I thought it must be fuel related as I was getting a variable idle. So I pulled the gas tank and changed the fuel pump. (Just a note if you plan on dropping the tank- make sure you have 2 replacement bolts and clips for the gas tank hold-down straps as they were rusted on).
I thought this would fix the problem but to my surprise it started up but still had the up and down idle. Next I changed the fuel filter (I didn't do it earlier because it looked fairly new). It started up and the idle was smooth.
I thought my problem was finally solved but now sometimes it won't start and if it does start if I shut it off and try to start it right back up it won't start.
I'm running out of ideas ???

I also pulled the tranny pan and it there was a quarter inch of black sludge in the bottom. Cleaned it and put 3 quarts of full synthetic, and new filter.

 

First, I'd test the theory that the hot-no-start problem is a fuel problem. I'm lazy, so I'd buy a can of ether ("Starting Fluid"), and take it and a 8mm nutdriver with me on my next trip. When you can duplicate the no-start condition, loosen the air intake elbow at the throttle body (remove the ice shield over the throttle linkage before, if you haven't already), open the throttle and give a two-second blast down the throttle body with the ether.

IMPORTANT!
Reconnect the air intake elbow.

Then try to start the rig.

Still No start?
a) Not a fuel delivery problem
b) Flooded -- check fuel regulator for failed diaphragm. BTW, this could also cause your variable idle, the regulator leaking fuel into the intake. Pull the vacuum line and sniff it -- it should NOT smell like fuel.

Starts? (briefly or not)
Perform fuel pressure test ([link:www.ford-trucks.com/dcforum/aerostar/378.html#2|https://www.ford-trucks.com/dcforum/aerostar/378.html#2])

With a new fuel pump, new filter, and runs OK on cold start, it's likely that if you have a fuel pressure problem that it's related to a failed fuel pressure regulator. Quite easy to get to on the 3.0l.

Regards,
Al S.

 

If you find a fix, PLEASE post. I have the same problem with our 93 replaced fuel pump/strainer/filter/relay. TFI (on firewall) TPS, idle air bypass valve, coolant sensors, oxygen sensor and just today I gave up and put in a new computer still the same. Please pass on any info thanks! --Tim

 

Clean the mass air flow sensor before replacing anything else. Do search on this board for instructions.

 

I still have not fixed the variable idle, however I have noticed that it idles fine until I turn the heater on, then it starts to rev up and down--if i turn heater off it idles fine again.

the no start problem which doesn't happen a lot is 100% a fuel problem as I sprayed some start fluid in throttle body and it started up. I bought a new fuel regulator from NAPA but it didn't match up so I haven't replaced it yet.

I cleaned the throttle body which was extremey dirty but didn't really seem to make a difference.

Its started up everyday for a couple weeks so I may hold off on the fuel regulator--I just need to fix the idle problem.

I'll post when I find a solution--may be someone has had similar problems.

 

Sounds like you've got air in the cooling system and/or low coolant level. No fluid in contact with the coolant temp sensor is giving erratic signals to the EEC unit.