I changed the plugs wires rotor and cap on my g/f 87 gmc s15 V-6 and
now it wont start, I have a chiltons and have verified the firing
order and even checked by bringing #1 to TDC and making sure the
piston was up and it was. I checked all my vac. hoses and still
this engine has TBI so the timing is computer controled but I wonder
if the computer is confused since i have put new parts in it.
I'm a pretty good wrench when it comes down to it but this is my 1st
and last GM. Any help with this problem would be greatly appreciated
Frustrated in FLA
Chilton manuals are junk IMHO. Also, the computer cannot be "confused" by
the parts you replaced. Are you sure you have the number one wire in the
right spot? Number one cylinder will be at the top twice during the cycle,
and because the distributor turns at half the crank speed, you could be 180
degrees out with your number one position. Also, verify the rotation of the
By the backfiring, it sounds like it is off time, which can be the result of
incorrect indexing of the distributor, incorrect wiring of the distributor
with respect to spark plug cables, or a slipped timing belt or chain.
Remember there are two TDC occasions..one between the compression
and power strokes, and one between exhaust and intake. Be sure you
are on the right one.
What firing order did you use?
GM used two entirely different V-6s in that chassis and their
firing order is different also.
Try 1-2-3-4-5-6 clockwise around the distributor.
#s 1-3-5 are on the _PASSENGER_ side of the engine #1 being the
#s 2-4-6 are on the _DRIVERS_ side #2 being the front most.
No, it's confused because you put the parts on wrong.
Timing, IMHO, is not just the advance that you are speaking about.
It takes into account everything needed to get the spark to the right
cylinder at the right time. And that includes the wiring of the distributor
spark cables. If you got them wrong, then you would get the symptoms
you have described.
Assuming you followed wiring diagram correctly, simply move wires at
dist to exactly backwards from where you put them--start w/#1. Assuming
fir. order is 1 6 5 4 3 2, swap 1 with 4, 6 with 3, 5 with 2. Get the
system? This should be sufficient to start, & then you can time it
'finely'. May be a chance you will need to walk the wires one step(move
each wire one place forward or one step backward): that's most u should be
off(if any) to reach the fine tune marks. HTH, sdlomi2
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