Hesitation in 1994 F-150 Ford 4.9 liter Inline Six, 2 Wheel Drive, AOD Trans


Whenever I come up on a grade or small brige it hesitates untill I am on the flat again.It also hesitates when I try to pass anyone. It runs fine on flat land.Thanks for your help an ideas.Have a great day an be safe.


Do you feel any vibrations in this “hesitation”?

 You should have the error codes read. Even if there is not a CEL (Check Engine Light) codes may be saved.  Some places will read them for FREE. Try Autozone or Advanced Auto Parts. Get the exact code not just their translation into English and post it back here. The codes are usually something like P1234 

 I am suspicious that it may be a fuel filter/pump issue.  

 How does it do when trying to accelerate from say 60 - 70 mph?   When was the last time you replaced the plugs and wires?


Thanks for the reply BeadssandBeads.Yes the vibrations seem to come from the engine. When I let up off the gas petal it stops.


Thanks for the reply Mr. Meehan. I will have the codes read next week.I change plugs and wires every 6000 miles. I just changed them 2 weeks ago.


Without driving the vehicle it is hard to tell what is going on. It could be misfire and the codes might tell us that as Mr. Meehan suggests. He could be right about the fuel supply as well. Along with the codes, it is easy to change the fuel filter so I would start there. If that does not help, check the fuel pressure as a sign of a bad pump.

The other thing I am worried about is the transmission. I wonder if you are getting shudder. That occurs when a clutch is trying to engage, but can not. Transmission shudder is often described as like running over rumble strips. This is AOD, does it still do the dance when you lock out overdrive? What is the condition of the trans fluid? If it is bad, it will be turning brown and might smell burned. Compare it to some new stuff. At any rate it should probably be serviced every 60K at most. If you haul or tow, more like 30K.

This transmission was originally supplied with Mercon. The same stuff is used in the power steering, I think. If the transmission has not been serviced recently, have the pan dropped, install a new filter, drain the torque converter and refill with Mercon V. It would be best to have it serviced by someone that knows what they are doing so they can ?read the tea leaves? in the transmission pan.

Plugs and wires every 6000 miles sounds like way too often.