Ford F-150

KBRAD

MEMBER
1915 FORD F-150

I have a 1994 ford f 150, 4.9, 6 cyl. Engine auto. Trans with 97,000 miles. It generally gets 21 miles per gal. And better. A couple of months ago, when it was still cold here, I started it and it started fine but when I gave it gas it died. It started right up again but smoked pretty heavy for several seconds. I tried giving it gas again and it died again, started fine again but smoked. Did this two or three more times and finally let sit and idle until it warmed up. Once it warmed up it ran fine. A few days later went thru this same ordeal only this time the check engine light came on after it had warmed up and I was on the road. The light just stayed on for a few seconds and when I had it checked it showed no codes stored in the system. The engine seems to be running fine but my gas mileage has dropped to 15 mpg. Along with this my trans. Seems to be changing at the right times but often slamming hard to the next gear when changing. Can you help? I'm sorry for such a long description but that's the best I could do. I really need help.
thanks,
kbrad

1 Reply

RUDPRO

MECHANIC
224 POSTS

I would get a vacuum gauge and test the intake vacuum with it. You might have a vacuum leak or other problem that's causing a lean condition and the computer is compensating by sending more gas to the cylinders. You should get a steady reading of about 17-21 inches at idle. Also, quickly open the throttle so it revs up to about 2500rpm, while looking at the vacuum gauge. It shold drop to near zero and quickly come back up to about 5 inches over normal vacuum and then return to the normal reading. If you don't get a steady reading at idle, there should be insructions with the gauge to interpret what's wrong, or post back with readings.