Hard starting, sluggish when cold.

prowler40 · 11-05-2006, 04:09 PM

I'm having issues with my 96 GMC, 5.7. It's hard to start and once started it's misses real bad until it finally gets warm. I've tested items such as the TPS, IAC, Intake air sensor, MAP and all check out OK. Even though it will miss while driving at steady throttle, it idles fine and will accelerate normal. It has a new fuel pump and the pressure is in spec.

Thoughts?

arcweldedprobe · 11-06-2006, 12:32 PM

...when you say "idles fine," do you mean idling in park, rolling forward, or braked at a stoplight? also, the "pressure...in spec;" is that from the fuel pressure regulator being tested or cylinder compression? thoughts (so far): fuel filter, distributer, timing, [maybe???spark plug quality/gap,] or maybe even gooey injectors...just things i've had in the past with similar symptoms...

prowler40 · 11-06-2006, 08:09 PM

Idles in park or drive, as soon as I take off it stumbles and runs rough for 3 or 4 miles and eventually smooth out. Pump pressure while running is 57 lbs. 62 lbs. with engine off. No time to work on it so I took to my mechanic this afternoon so he can start it on the diagnostic and hopefully will see what it's doing at first start.

11-05-2006, 04:09 PM	#1
prowler40 Junior Member Join Date: Jan 2006 Location: Oregon Posts: 5	Hard starting, sluggish when cold. I'm having issues with my 96 GMC, 5.7. It's hard to start and once started it's misses real bad until it finally gets warm. I've tested items such as the TPS, IAC, Intake air sensor, MAP and all check out OK. Even though it will miss while driving at steady throttle, it idles fine and will accelerate normal. It has a new fuel pump and the pressure is in spec. Thoughts?

11-06-2006, 12:32 PM	#2
arcweldedprobe Full Member Join Date: Oct 2006 Posts: 14	...when you say "idles fine," do you mean idling in park, rolling forward, or braked at a stoplight? also, the "pressure...in spec;" is that from the fuel pressure regulator being tested or cylinder compression? thoughts (so far): fuel filter, distributer, timing, [maybe???spark plug quality/gap,] or maybe even gooey injectors...just things i've had in the past with similar symptoms... __________________ the smell of stale coffee, a bead of sweat in my eye, black grease under my nails...garage poetry...

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11-06-2006, 08:09 PM	#3
prowler40 Junior Member Join Date: Jan 2006 Location: Oregon Posts: 5	Idles in park or drive, as soon as I take off it stumbles and runs rough for 3 or 4 miles and eventually smooth out. Pump pressure while running is 57 lbs. 62 lbs. with engine off. No time to work on it so I took to my mechanic this afternoon so he can start it on the diagnostic and hopefully will see what it's doing at first start.