2004 Jeep Grand Cherokee high RPMs

MICHAELODELL

MEMBER
2004 JEEP GRAND CHEROKEE
4.0L
6 CYL
2WD
AUTOMATIC
150,000 MILES

WE JUST DID A VALVE JOB AND REASSEMBLED. WHEN STARTING, THE ENGINE RUNS AWAY. EVEN WITH A RAG BLOCKING THE CARB. IT IDLED FINE BEFORE TEAR DOWN WHATALL SHOULD WE TRY?
ALL VACUM LINES SEEM TO BE INTACT.I'M NOT THERE, BUT MY BUDDY SHUTS THE ENGINE DOWN IMMEDIATELY. HE'S WORRIED IT WILL BLOW UP OR CAUSE DAMAGE.
THANKS

3 Replies

SATURNTECH9

MECHANIC
30,869 POSTS

Sounds like a vacuum leak especially if its still doing it with the throttle body blocked off. Get some canned smoke spray it into vacuum hose for the brake booster and see where the smoke is escaping. Should be easy to find.

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Thursday, December 5th, 2013 AT 12:56 PM

MICHAELODELL

MEMBER
2 POSTS

WHERE CAN YOU BUY CANNED SMOKE. OR WILL ANYTHING ELSE WORK. ALSO CAN THIS BE DONE WITH THE ENGINE OFF?

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Thursday, December 5th, 2013 AT 1:07 PM

SATURNTECH9

MECHANIC
30,869 POSTS

I have seen canned smoke they use test smoke detectors you can use it with the engine off and must use it with the engine off. You could also use a cigar dont usually smoke them but worked in a pinched. You have to use a plastic bag to block off the throttle body before using smoke.I know they sell canned smoke on the internet not sure what stores in your area that might carry it.

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Thursday, December 5th, 2013 AT 1:16 PM