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1999 jeep cherokee. just bought it. was idling low and check…

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1999 jeep cherokee. just bought...
1999 jeep cherokee. just bought it. was idling low and check engine light came on today. shows code p1494. research shows it could be Leak Detection Pump Sw or Mechanical Fault. I am debating on whether or not to fix this or take it back to the dealer. I have found that it could just be a leak. Advice?
Submitted: 8 years ago.Category: Jeep
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Answered in 11 minutes by:
6/27/2010
Jeep Mechanic: Chris, Shop Foreman replied 8 years ago
Chris
Chris, Shop Foreman
Category: Jeep
Satisfied Customers: 14,944
Experience: Jeep Certified Master Tech
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Hello and welcome to just answer Jeep. Your Jeep has an emission system for containing fuel vapors known as the Evaporative Emission System. There is a device known as the Leak Detection Pump (LDP) that tests the Evap system for leaks. The PCM (engine computer) runs tests on the LDP to make sure it is operating properly and will set a trouble code if these tests fail. Now the code you have will set if the PCM does not see the switch inside of the LDP change state when it is supposed to. This can be a loss of vacuum to the pump, a wiring problem, or the LDP itself. When ever I see this code, 9 times out of 10 it is a vacuum line that has come off at the intake manifold. So look for any vacuum lines that may have come off around the intake manifold. Also check the lines at the LDP. If you can tell me what engine you have I will let you know where the LDP is.
Hope this helps,
 
Chris
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Customer reply replied 8 years ago
4.0L High Output 6 Cylinder Fuel Injected Engine is that enough info?
Jeep Mechanic: Chris, Shop Foreman replied 8 years ago

Yes that is enough info. Here is the information from the service manual. Hope this helps,

 

Chris

 

LEAK DETECTION PUMP (LDP)

The LDP is located in the right-rear side of engine compartment EVAP Canister Purge Solenoid (With LDP) The LDP filter is located above the LDP EVAP Canister Purge Solenoid (With LDP) The LDP and LDP filter are replaced (serviced) as one unit.

REMOVAL

  1. Carefully remove hose at LDP filter.
  2. Remove LDP filter mounting bolt and remove from vehicle.
  3. Carefully remove vapor/vacuum lines at LDP.
  4. Disconnect electrical connector at LDP.
  5. Remove 2 LDP mounting screws EVAP Canister Purge Solenoid (With LDP) and remove from vehicle.

INSTALLATION

  1. Install LDP to mounting bracket. Tighten screws to 1 N·m (11 in. lbs.) torque.
  2. Install LDP filter to mounting bracket. Tighten bolt to 7 N·m (65 in. lbs.) torque.
  3. Carefully install vapor/vacuum lines to LDP, and install hose to LDP filter. The vapor/vacuum lines and hoses must be firmly connected. Check the vapor/vacuum lines at the LDP, LDP filter and EVAP canister purge solenoid for damage or leaks. If a leak is present, a Diagnostic Trouble Code (DTC) may be set.
  4. Connect electrical connector to LDP.

 

graphic

 

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Customer reply replied 8 years ago
could this cause it to idle low?
Jeep Mechanic: Chris, Shop Foreman replied 8 years ago

Probably not. A low idle is most likely caused by a dirty throttle body, or a sticking Idle Air Control motor (IAC). For your idle problem I recommend cleaning out the inside of the throttle body and the throttle plate. Purchase a can of sprat throttle body cleaner and follow the directions on the can. If the idle is still too low, then replace the IAC.

 

Chris

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Customer reply replied 8 years ago
Now if I may ask your opinion. I just bought the Jeep Thursday and could probably take it back to the dealer I got it from and basically return it. I know this is a used car, it only has 64,000 miles on it. In your opinion do you think this is to many problems for a used car and should I return it?

Thanks
Dana
Jeep Mechanic: Chris, Shop Foreman replied 8 years ago

First of all I would ask the dealer to take care of these issues since you just bought it. They should warranty these repairs. These are both very minor problems and I would not be too concerned about this. The Cherokee is actually a pretty reliable vehicle. If it was maintained fairly well, then you should be able to get many miles out of it.

Hope this information helps, and let me know if you need more assistance with this Dana,

 

Chris

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