Z engine code wont run

Asked by Guru6RRZJ Mar 31, 2020 at 10:50 PM about the 1989 Chevrolet S-10 Tahoe RWD

Question type: Maintenance & Repair

I give up on this truck I replaced engine was
running with blown up engine replaced with known
good engine along with a new complete distributor
getting good fuel pressure  and getting spark but
will not run good fuel pulse  firing order is right
everything checks out.  Still scratching my head as
to why it wont run.  Cranks over good  good
grounds.  Everything I know tells me it should start
and run but it dont.  I dont get it. All the fuses are
good.   Got good oil pressure while cranking over.

2 Answers

30

Sounds like a good ol' case of bad ignition timing. Have you checked that while cranking? I just overhauled a 91 Silverado engine and ignition timing kicked my A** for three days. Cut your fuel pump relay and roll the engine over. Put you a timing light on the 1L cylinder spark plug wire and watch the harmonic balancer. The balancer has a mark on it for TDC (top dead center) and on the timing cover (front cover behind the crank pulley) there is a tab that comes off. the wide V in the tab indicates 0 degrees. There are lots of other things that can effect this mark but we're just assuming you got a factory engine. While rolling the engine over you want to have the timing light flash within these marks. this should get you running. Shut back down and disconnect the ignition module BYPASS connector. Usually located by the ECM strip on the firewall next to the fuel pump relay. (one prong connector). start the engine and check timing. Get it in the mark with the balancer. Once done, shut down, plug in the connector, disconnect the battery for 30 secs. reconnect and start up. Should be good from there.

30

EDIT: if your timing is not correct then you will need to loosen the distributor and turn it one way or the other until it is. Do this while the ignition bypass is disconnected.

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