Grand Cherokee motor fail

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  #1  
Old 04-13-10, 12:33 PM
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Grand Cherokee motor fail

One wek ago I was driving about 60 m/h and my car (2001 Grand Cherokee 4.0L) stop suddenly, I tried to start and I couldn't hear the fuel pump working. After 1 hour I tried to run and It worked properly. But to be sure I changed the fuel pump and the filter " fuel pump used" and It worked. But last weekend I tried to start by six o seven times and It doesn't worked, but I can see fuel in the line near to the injectors, then I removed the spark plugs conections and disconnected the battery cable to restart the motor and It worked. Yesterday I was driving just 2 blocks from my home and the motor stop suddenly again, after turned of totally It worked again quickly. When the motor stop it doesn't something strange, just stop and the RPM's goes from 2000, 2500 to 0 in a second. Another information, since that change I must try two or three times to start the motor, mostly in cold.
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Old 04-14-10, 09:29 AM
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Test the fuel pressure with a fuel pressure gauge.

Test the power going to the fuel pump with a multimeter.

This testing is easiest done by using the factory service manual set of books which you can order from your dealer. These books have complete wiring diagrams and complete detailed troubleshooting instructions. (Get the right tools for the job! Fuel pressure gauge, multimeter, factory service documentation.)

Then test/service the *entire* fuel system, not just the pump...
Fuel Injection Service, Not Just Cleaning
 
  #3  
Old 04-14-10, 04:10 PM
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I know money can be tight at times......But NEVER EVER, use a "used" Fuel Pump on a personal vehicle.

Having said that. beg , borrow or steal a fuel pressure gauge, and check pressure when the truck is running well, and then again when it acts up.....

A sore spot with Jeep 4.0l motors, is the way the wiring harness passes over the fuel rail. Ive seen literally hundreds of them, with the harness rubbed thru,and the injector drivers shorted momentarily. This locks the injector open, fills the manifold with fuel and explains the hard start while the engine is trying to clear out the flood. Drivers side, toward the rear of the intake manifold.

Typically, fuel pressure problems will not "Kill" or "Stall" an engine instantly, but rather it will wither away as fuel pressure drops.
 
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