Author Topic: Runs rough at startup  (Read 2975 times)

Offline richjr74

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Runs rough at startup
« on: October 20, 2010, 12:34:15 pm »
Guys, my 87 TBI 350 only runs rough in the morning at first crank.  When i start the truck it idles perfectly.  In "park" i can press on the accelerator and it revs fine but in gear if i don't go 3/4 throttle at least, it misses or feels like it misses.  After a few miles of driving it run perfectly.  I'm not a mechanic but it seems if it were timing, distributer, plugs, plug wires, etc... these symptoms would be all the time and not just the first time i start it in the mornings.  Anyone experience this? 
87 GMC Sierra 350 4X4...60k original miles!

Offline Layne

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Re: Runs rough at startup
« Reply #1 on: October 20, 2010, 02:01:49 pm »
It sounds like a sensor. Do you have a ses on?
77 c-10 - 77 400 86 700r4 "Emmy"
83 citation - 2.5L Four on the Floor!
88 sierra - reman 350 700r4 "Eleanor"
All normal practicality and rational money handling goes out of the window when it comes to my truck.

Offline richjr74

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Re: Runs rough at startup
« Reply #2 on: October 20, 2010, 02:06:14 pm »
SES?  Not sure...there is no check engine light on. 
87 GMC Sierra 350 4X4...60k original miles!

Offline VileZambonie

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Re: Runs rough at startup
« Reply #3 on: October 20, 2010, 09:13:23 pm »
Check the vacuum hose going to the map sensor. Make sure it's not too long or kinked etc. Check the engine coolant temp sensor as well. Jump the A&B terminal of the data link connector and see if it has any DTCs
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Offline richjr74

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Re: Runs rough at startup
« Reply #4 on: October 21, 2010, 07:19:24 am »
thanks, i'll give that a shot. 
87 GMC Sierra 350 4X4...60k original miles!