2004 explorer 4.0sohc no vacuum.wont run | Ford Explorer Forums - Serious Explorations

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2004 explorer 4.0sohc no vacuum.wont run

terrance bond

New Member
April 23, 2018
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Year, Model & Trim Level
2005 explorer xlt
the following has been replaced,,new fuel pump ,fuel filter ,,spark plugs ,new fuel rail pressure sensor,,new crank sensor,new throttle body assy,,checked compression 150 psi across all cyl ..good injector pulse,80 psi fuel pressure.,,good spark ,,no codes ,,the pats system light appears to working to specs.no vacuum at the any port.we removed the intake after smoking the intake and found a major leak at the egr valve assy,.when the intake was off we left a rag over the intake ports and when the motor was cranked it tried to suck the rag into the motor,.this make me think we have good vacuum .we installed a used upper intake off a running 4.0 and we still don't have any vacuum when cranking.we have removed the fuel pump relay and tried to start the vehicle ,it tries but no fire ..but if you let the vehicle set 1 minute it will fire for about 30 seconds.

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Sorry, hard to follow your descriptions. You obviously "have vacuum" if the intake ports are trying to suck in a rag. Did you replace the intake manifold (plenum) gaskets with new Felpro or Reintz/motocraft gaskets?

What is the story with this truck? Did you buy it with a non-running engine and are trying to get it running for the first time for you? Why do you think there's a problem with the vacuum?

How many miles? Clogged cat?

the truck came to me not running we found that the cats had plugged up and melted .

Failed cats usually mean there was an engine issue that caused the failure. Like dumping unburnt fuel down the exhaust manifold that then ignites in the cat and melts it. Timing failure on one side can do this.
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So can a malfunctioning/missing EGR system.