Bucking, jerking

Tiny
CROLEN
  • MEMBER
  • 2006 FORD F-150
  • 5.4L
  • V8
  • RWD
  • AUTOMATIC
  • 165,000 MILES
When I accelerate up a hill or when I am traveling at 50 to 55 mph and accelerate slightly, my truck will bump or jerk a few times. At first I thought it was transmission, but it shifts smoothly and the tachometer doesn't move when it does it. There is no check engine light. Is it possibly a cylinder misfire? I thought that would cause a check engine light but maybe not. It will accelerate smoothly on a flat surface through all gears up to top speed. I also tried locking it in 1st gear and took it to 4500 rpms smoothly and the same in 2nd. It only jerks going up a hill or slightly accelerating on the highway from about 50 to 60 miles per hour.
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Wednesday, February 3rd, 2016 AT 2:40 PM

3 Replies

Tiny
HMAC300
  • MECHANIC
  • 48,606 POSTS
Check for a vacuum leak, fuel pressure with a gauge, autoparts rent gauge, and air leaks first if no codes.
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Wednesday, February 3rd, 2016 AT 3:25 PM
Tiny
CROLEN
  • MEMBER
  • 1 POST
Does the 5.4 liter engine have a pressure test port on the fuel line, and if so where.
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Wednesday, February 3rd, 2016 AT 3:51 PM
Tiny
HMAC300
  • MECHANIC
  • 48,606 POSTS
It doesn't have a Schrader valve you wil probably need an adapter for it. Fuel pressure 28-45 psi engine running and 35-45 key on only
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Wednesday, February 3rd, 2016 AT 4:31 PM

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