GMC truck 5.7L pulsates at idle

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pepper57
Posts: 1
Joined: Thu Sep 26, 2013 2:49 pm

GMC truck 5.7L pulsates at idle

Unread post by pepper57 » Thu Sep 26, 2013 3:01 pm

I am 16 and have a 1995 gmc k1500 5.7 it pulsates at idle and stalls, so far I have a new cap, rotor, module, wires, plugs, maf sensor, throttle position sensor, fuel pump and pressure reading is 13 to 15 pounds. Thermostat sensor for computer. It still pulsates after computer is bringing down idle and then it will stall but it will start right back up.

Please help I am stumped. I have done everything my Haynes manual has told me to and now I still have the problem and low on money help please.

scotty
Posts: 19
Joined: Sun Oct 14, 2012 11:52 am

Re: GMC truck 5.7L pulsates at idle

Unread post by scotty » Fri Sep 27, 2013 10:15 pm

It sounds like you have a vacuum leak. A vacuum leak causes a lean condition (too much air- not enough gas) and will cause a fluctuating idle and stalling.

Spray some brake cleaner around- being sure to stay away from all ignition components. If a leak is found, the idle will surge up then down very noticeably.

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