Rough idle

Tiny
VASPUTANT
  • MEMBER
  • 1997 LINCOLN TOWN CAR
  • 4.6L
  • V8
  • 2WD
  • AUTOMATIC
  • 195,000 MILES
Start engine runs low idle. As it warms up idle surges up and down. When it warms up it runs ruff. I have changed TPS, IACV, EGR, intake manifold, PCV, sparks, ignition wires, fuel filter. Fuel pump has 30lb.
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Friday, June 15th, 2018 AT 3:49 AM

1 Reply

Tiny
ASEMASTER6371
  • EXPERT
Good morning.

Your fuel pressure is low and most likely causing this issue.

It should be a minimum of 35 but better at 40.

Roy

https://www.2carpros.com/articles/how-to-replace-an-electric-fuel-pump

https://www.2carpros.com/articles/engine-surges

Warning: Do not smoke, carry lighted tobacco or open flame of any type when working on or near any fuel related component. Highly flammable mixtures are always present and may be ignited, resulting in possible personal injury.

Caution: Fuel supply lines will remain pressurized for long periods of time after engine shut down. This pressure must be relieved before servicing of the fuel system is begun. A valve is provided on the throttle body for this purpose. Remove the air cleaner and relieve system pressure by using Rotunda pressure gauge tool T80L-9974-A or equivalent and drain the system through the drain tube.

Removal:

1. Place vehicle on hoist, do not raise.
2. Perform fuel system release procedure.
3. Drain fuel from fuel tank.
4. Raise vehicle on hoist. Use proper vehicle lifting procedures.
5. Remove fuel tank and move to bench.
6. Remove any dirt that has accumulated around the fuel pump module so that it will not enter the fuel tank during removal and installation.
7. Remove six bolts from around perimeter of fuel pump module.
8. Remove fuel pump module from fuel tank.
9. Remove o-ring seal and discard.
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Friday, June 15th, 2018 AT 4:29 AM

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