91 silverado won't start

clarkster · 10-08-2009, 09:20 AM

replaced the ecm,coil and still no help.Is there a crank or cam sensor to keep it from running?Will start once in a while(long while)but when I turn it off it will not refire.Any help on where to start?Starting fluid does not help.

bradrhale · 10-08-2009, 09:39 AM

do you have spark?? how about compression on each cylinder??

clarkster · 10-08-2009, 10:08 AM

no spark when it won't start.All wires look good.Didn't do a compression check but when it starts runs fine no smoke.

bradrhale · 10-08-2009, 10:13 AM

no spark at coil either, im assuming?? if not but have changed the coil, and assuming its good, check for hot at the coil. another thing, do you have spray at your injectors??
this is starting to point towards an ignition module problem. it is located under the dizzy cap. when bad, it will kill spark.

clarkster · 10-08-2009, 10:31 AM

replaced ignition module,coil,cap,rotor button.When problem started took ignition module to be checked and came up bad.The new one made no difference.tested new one and came back good.Is there a crank or cam sensor on a 91 305 ci motor?

bradrhale · 10-08-2009, 10:37 AM

those would not kill the ignition.
are the injectors spraying?? are you getting a hot wire to the coil?? you should have 3 wires at the coil. all the time hot when ignition is on, ground which sends the voltage down the line through the coil wire and the coil wire itself. have you looked at all the fuses in the fuse panel??

clarkster · 10-08-2009, 10:41 AM

checked fuses inside cab.Did not check under hood.I'll check coil to see if hot with switch on.No cam or crank sensors on these models?

Case 7230 · 10-08-2009, 10:43 AM

Can`t answer your question but have you checked for trouble codes? You can do that even if you don`t have a code reader.

bradrhale · 10-08-2009, 10:43 AM

yes, do you think that one could be your problem??

clarkster · 10-08-2009, 10:53 AM

checked for trouble codes came back 12 which i was told all good.Did just check power to coil.I have 2 split plugs on coil,each have a red and white wire.I have power on one red with key on.I'm assuming the other red would be hot in start mode when starter is engaged

10-08-2009, 09:20 AM	#1
clarkster Junior Member Join Date: Oct 2009 Posts: 8	91 silverado won't start replaced the ecm,coil and still no help.Is there a crank or cam sensor to keep it from running?Will start once in a while(long while)but when I turn it off it will not refire.Any help on where to start?Starting fluid does not help.

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10-08-2009, 09:39 AM	#2
bradrhale Senior Moderator Join Date: Apr 2006 Location: Texas Posts: 8,030	do you have spark?? how about compression on each cylinder??

10-08-2009, 10:08 AM	#3
clarkster Junior Member Join Date: Oct 2009 Posts: 8	no spark when it won't start.All wires look good.Didn't do a compression check but when it starts runs fine no smoke.

10-08-2009, 10:13 AM	#4
bradrhale Senior Moderator Join Date: Apr 2006 Location: Texas Posts: 8,030	no spark at coil either, im assuming?? if not but have changed the coil, and assuming its good, check for hot at the coil. another thing, do you have spray at your injectors?? this is starting to point towards an ignition module problem. it is located under the dizzy cap. when bad, it will kill spark.

10-08-2009, 10:31 AM	#5
clarkster Junior Member Join Date: Oct 2009 Posts: 8	replaced ignition module,coil,cap,rotor button.When problem started took ignition module to be checked and came up bad.The new one made no difference.tested new one and came back good.Is there a crank or cam sensor on a 91 305 ci motor?

10-08-2009, 10:37 AM	#6
bradrhale Senior Moderator Join Date: Apr 2006 Location: Texas Posts: 8,030	those would not kill the ignition. are the injectors spraying?? are you getting a hot wire to the coil?? you should have 3 wires at the coil. all the time hot when ignition is on, ground which sends the voltage down the line through the coil wire and the coil wire itself. have you looked at all the fuses in the fuse panel??

10-08-2009, 10:41 AM	#7
clarkster Junior Member Join Date: Oct 2009 Posts: 8	checked fuses inside cab.Did not check under hood.I'll check coil to see if hot with switch on.No cam or crank sensors on these models?

10-08-2009, 10:43 AM	#8
Case 7230 Senior Member Join Date: Dec 2007 Posts: 547	Can`t answer your question but have you checked for trouble codes? You can do that even if you don`t have a code reader.

10-08-2009, 10:53 AM	#10
clarkster Junior Member Join Date: Oct 2009 Posts: 8	checked for trouble codes came back 12 which i was told all good.Did just check power to coil.I have 2 split plugs on coil,each have a red and white wire.I have power on one red with key on.I'm assuming the other red would be hot in start mode when starter is engaged