1998 GMC Sierra 1/2 ton 4.3L

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  #1  
Old 05-07-03, 05:47 PM
reyes45's Avatar
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Question 1998 GMC Sierra 1/2 ton 4.3L

My truck started running rough whith check engine light on.
I scanned it with my OBDII scanner and got code P300(multiple
cylinder misfire) so I changed spark plugs, dist. cap, rotor, and
wires and it did not fix the problem. #3 plug dark with gas odor.
What else could it be? Thank you.
 
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Old 05-08-03, 03:58 AM
Joe_F
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Could have a bad coil, or commonly on the 4.3 the fuel injector poppets get clogged and it will run rough. Could also have a bad fuel pressure regulator diaphragm.

How's the fuel pressure?
 
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Old 05-08-03, 03:27 PM
reyes45's Avatar
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1998 GMC Sierra 1/2 ton 4.3L cylinder misfire

Fuel pressure is good. problem comes from misfire. I suspected
sparkjump in dist cap but that wasn`t the case. hink I`ll have
the ign. module and coil checked. What do you think?
Thank you for your reply!
 
  #4  
Old 05-08-03, 03:43 PM
darrell McCoy
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Joe's gotcha covered on the partial clogged fuel injector. If so GM has a decent additive. Not recommended for continous use however. Part number escapes me right now but is about 18 bucks for a bottle.
 
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Old 05-08-03, 04:01 PM
Joe_F
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Original poster: How do you know the fuel pressure's good? How was it checked?
 
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