So my little brothers 87 f-150 had never had any trouble. He was driving back home one sunday and it suddenly began sputtering/cutting out etc……intermittently…He soon realized that if he drove literally 85 mph and above it was fine. It would only act up if he slowed to pass etc.

On arriving home, at idle there was literally raw liquid gas leaking out of several of the manifold ports at the head…..also out the exhaust pipe. I do believe ALL cylinders were heavily over fueling, but only leaking at head on a few due to leaky gaskets.

After some reading, He decided the temp sensor may have failed making the brain believe it was really cold out maybe? So after he put the temp sensor in, he's never seen raw gas flooding out, but it smells excessively rich and randomly backfires which it never backfired before he put the temp sensor in!

Every component has been either tested or replaced, coil, cap and rotor, dist mounted IGN module, IAC etc. We pulled the computer and looked for VISIBLE problems (burned diodes etc) and found nothing…..

My theory now is that maybe the temp sensor failed, sending it into a severe over fueling condition…..during that time the 02 sensor became plugged and or ruined. Thats the only component he HASNT replaced or pulled out. Im leaning this way because the symptoms clearly changed when the temp sensor was replaced.

He has a 460 hes wanting to drop in it, and is at his wits end with this thing LOL

Any advice, thoughts, experiences are appreciated.

Hes gonna get another new temp sensor and an 02 sensor today and if that don't fix it, he's probably gonna be looking for a lighter…...

 

Did you guys check out the fuel pressure reg vac line? Any signs fuel has been in it?

What is the fuel pressure reading?

 

I know he checked the fuel pressure….ill have to ask him what it was….


also it starts great, always has….the exhaust is rich enough where it'll burn your eyes in the shop in a minute