Why does my truck die when stopped or in park every time?


Asked by Jul 26, 2016 at 09:25 PM about the 1993 GMC Sierra 1500 C1500 SLE Standard Cab SB

Question type: Maintenance & Repair

My truck's rpm is acting up, the idle is
rough, the air intake valve has been
replaced with a new one from the
factory, the throttle body has been
checked gasket replaced, spark plugs
are brand new ac delco's, fuel is
coming through the lines, truck is
acting as if I was driving a stick shift
and dies without putting my foot in the
clutch. Oil is good, battery is at 15, 3
different mechanics have looked at it
and can't seem to pin point it. Please

1 Answer


After replacing the Erg valve, the ignition module, the air intake valve, map sensor, all new AC Delco spark pkugs, doing a fuel pressure test, blowing out any gunk stuck in my lines, and cleaning out the trottle body; I took a break on Saturday and read two books front to back on how to read schematic diagrams and how horse powered engines work. I was tired of reading about what everyone else did or thought and just focused on my specific issues. My truck starts fine. As soon as I would take off the the rpm needle went mad. My temperature gauge always read at 210 during the day and these last 24 days it has been reading a quarter of that but running hot. When doing 75-80mph in 85+ degree heat I would drive it in overdrive. When in reg drive the rpm was red lining in the 4-5 zone and felt like it was hesitating on shifting when acclerating. I am starting to rule out short and think temperatur , probably my thermostat or water pump. Thermos can shut circuitry off to protect the engine and totally bypass the ecm to read normal. When stopped at a light when in drive it would do 2-4 little rumbles then choke and die. If in park it would last a little longer but still idle'n rough and die. It would start up again but super irritating and just impossible to deal with if stuck in bumper to bumper traffic. If I put it in neutral it wouldn't die. We ran several tests, my diagnostic check just blinks reg 12 over and over again. So I get my friend in my truck we take it for a spin he says pull over and pulls the coolant sensor. The small black snap in one in the front of the carburator behind the belts. Engine like on but runs perfect now! So all I need is a new coolant sensor.

Your Answer

GMC Sierra 1500 Experts

  • #1
  • #2
    John Saffrahn
  • #3
    Glenn Clingenpeel
View All

Related Models For Sale

Used Ford F-150
2,302 Great Deals out of 215,045 listings starting at $1,300
Used Dodge Ram 1500
308 Great Deals out of 9,480 listings starting at $1,750
Used GMC Yukon
330 Great Deals out of 19,939 listings starting at $1,400
Used Chevrolet Camaro
242 Great Deals out of 28,827 listings starting at $1,800
Used Chevrolet Corvette
98 Great Deals out of 15,350 listings starting at $3,900

Used Cars For Sale

2018 GMC Sierra 1500 For Sale
18 Great Deals out of 31,734 listings starting at $23,873
2017 GMC Sierra 1500 For Sale
72 Great Deals out of 5,415 listings starting at $19,900
2016 GMC Sierra 1500 For Sale
63 Great Deals out of 2,814 listings starting at $16,422
2015 GMC Sierra 1500 For Sale
77 Great Deals out of 4,681 listings starting at $13,995
2014 GMC Sierra 1500 For Sale
75 Great Deals out of 3,065 listings starting at $13,500

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use.