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chevy 4.3 multicylinder misfire

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  • chevy 4.3 multicylinder misfire

    fuel pump good. fuel filter changed. just did plugs, wires, cap and rotor. was running great until yesterday. only thing I can think of is I got gas at a chevron. just the occasional misfire at idle and more at cruise but it accelerates hard with no problems.
    might swap the coil if i can find a used one.

  • #2
    Could be the fuel injectors. Pretty common on the 4.3L.

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    • #3
      has the CSFI system which ive never worked on myself.

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      • #4
        very possible it needs a spider assy...check the fuel first of course
        Ring and pinion specialist

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        • #5
          mine ended up being a worn dist gear causing eratic timing, this was on my 03 s10 i had at the time. the spider assembly is known for leaking aswell
          81 LX
          82 GT

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          • #6
            Spider injectors...

            See it all the time.

            320rwhp. 7.67 @ 90mph 1.7 60'

            DD: 2004 GMC Sierra VHO 6.0 LQ9 324whp 350wtrq

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            • #7
              truck sat for a couple of years so Im assuming maybe has crud in the lines. I was hoping seafoam would help but hasnt so far yet.
              Just throwing me off because it isnt acting like fuel- ie. no popping, white smoke. acts more like its cutting out/misfire. guess ill start tearing into it after i prepare for tommorrow Bible class

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              • #8
                check the fuel pressure, and see if is hold the pressure after turn the key of.

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                • #9
                  sitting for 2 years, hope ya cleaned out the tank.unless they added fuel stabilizer in it. i just tore down a 4.3 in a blazer.. not to bad a motor really..
                  http://i89.photobucket.com/albums/k2...g/P1010006.jpg

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                  • #10
                    Those spider assy's are the devil, what were thinking coming up with that junk?

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                    • #11
                      dont have a fuel pressure tester but did test the coil with a multimeter and shows to be bad??
                      anyone tried the fuel pressure testers from harbor freight?

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                      • #12
                        and another thing is the cheap distributor caps crossfire badly, id start with an ac delco cap and see if that takes care of it cuz its the cheaper of the parts and the usual cause from what ive seen.

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                        • #13
                          cheap cap will kill it i installed a oriellys special on my mark and it started missing went to change it back to the accel cap and rotor pulled a couple of the plug wires and the teminals pulled right threw as well as the coil terminal.

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                          • #14
                            cap is ok. fuel pressure about 50 at ignition on and about 55 running. unable to see if it was actually holding pressure since the cheap guage was leaking at the fitting. althought theres no smoke at start up and starts up without delay. slight misfire seems to worsen when the engine warms up thats why Im suspecting the coil? not sure where the pickup coil is in this system but usually it wont run when that goes bad. as soon as i got one vehicle fixed the other has to act up

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                            • #15
                              fuel pressure should be key on engine off 60-66 psi. but you have to see if is holding that pressure, if is not holding pressure you have a leak on fuel inj spider, or fuel pressure regulator, witch is on the same place. Do you have check engine light on. (code number)

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