Quote:
Originally Posted by NATIONAL87
I know this is a very very old thread but I have a 2001 4.3 vortec doing the exact same thing..runs great when first started..then 5-8 miles down road it runs rough under 2k basically..sets a check engine light & show to have misfire on three same bank cylinders..do you think this may be the fuel regulator or still possibly the spider?
W code 4.3 2001 model..replaced cap,rotor & fuel pump..
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you need to check the fuel pressure..it must be 60-66 psi..key on engine running...with the key off the fuel pressure should hold steady and fall only a few psi in 10minutes...
if it falls off rapidly this may mean the fuel regulator/metering, injector , fuel pump....
to replace the regulator you must remove the upper intake manifold.
after that I would check for vacuum leaks PCV system etc...