1988 Mercury Marquis will only run above 1/2 throtle

Tiny
ROCKY_TOP
  • MEMBER
  • 1988 MERCURY MARQUIS
  • V8
  • 2WD
  • AUTOMATIC
  • 140,000 MILES
The car will start and then die unless you rev the engine. After a while it will get closer to running at an idle. I replaced the plugs, wirers, cap, and rotor. I thought that it could be the fuel pump but it runs at highway speeds without stalling. The problem started sudenly and I am not getting a check engine light.
Sunday, January 3rd, 2010 AT 2:47 PM

2 Replies

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Hi rocky_top Welcome to 2carpros and TY for the donation and selecting us as your auto repair site. Feel free to ask questions at anytime

Check and test the idle speed control solenoid, Manifold absolute pressure sensor and throttle position sensor-Also do a fuel pressure check to rule out the fuel pump if its within specs-could be on its way out
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Monday, January 4th, 2010 AT 11:32 AM
Tiny
ROCKY_TOP
  • MEMBER
  • 2 POSTS
It was the map sensor
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Sunday, January 10th, 2010 AT 2:39 PM

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