So my 91 f150 won't start if it's below 25 degrees or so. Higher than 30, it lights right up. At 20 degrees, it cranks and cranks but won't fire.

I tried shooting ether into the throttle body, which did nothing. I put in new plugs, wires, distributor cap and rotor, but nothing changed. Also tried a new ECT sensor.

It also misses when it pulls hard.

Any ideas?

 

I put in a new coil today. No go. Still open to suggestions.

 

with the new coil in can you confirm that you have spark? I had a similar problem which ended up being a bad ground wire off the battery. I know alot of people preach this but it's true, start with the basics. Check the connections on your battery and all the grounds in the engine bay. Next, make sure your injectors are getting gas. If those are both good there are two relays on the driver side behind the airbox that I would check next, here is a picture http://i54.photobucket.com/albums/g9...lPumpRelay.jpg
best of luck!

 

Thanks for your reply. I have no prob going back to basics, but wouldn't the ether I shot into it eliminate fuel? I checked for spark by connecting an inductive timing light to the front cylinder wire. The light flashed even when the truck refused to start.

I haven't paid much attention to the battery, since it cranks like crazy, but I'll have another look.

 

What if it were a leaking injector or something, and actually running too rich to fire when cold?

 

X2 on this.

Other notions, ideas, advice...
Check for DTCs.
Run KOEO
Run KOER - (If applicable, when its running)
Check fuel psi

Try pulling SPOUT jumper when it won't start.
Try warming the ICM with hair dryer and/or distributor. The stator for the PIP is enclosed the distributor. I had similar problem where my 4.9 wouldn't start in cold weather and pulling the SPOUT jumper did allow it to start in cold weather.

Another thought......and its a doozy. The 4.9 EFI's seemed to be plagued with failing ECM's due to leaking/bulging/blown capacitors. Do a search for this and it'll find related posts.

Go through the list and report back your findings. If you feel motivated, you can take the time and pull the PCM. I suggest the earlier suggestions before the latter.

Let us know.

 

What's a SPOUT jumper?

I got the two relays from NAPA this morning. The parts for this thing are cheap enough so that I don't mind replacing stuff as I go. Besides, most of the stuff Ive taken off has been compromised in some way.

I bought a code reader, but the manual says it won't work if you can't start the engine. As soon as it warms up I'll check that stuff.

 

Hot Damn! It was the EEC relay. The old one was dangling around loose and unprotected. Probably why there was water in it. Thanks everybody.