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73-87 Chevy _ GMC Trucks => Electrical => Topic started by: rusty but trusty on November 15, 2012, 05:04:34 pm

Title: est timing issue looking for shorts
Post by: rusty but trusty on November 15, 2012, 05:04:34 pm

my truck is a 87 gmc v1500 all stock with tbi if i leave the set timing wire unhooked it runs fine but if i hook it back up and start it it only stays running if i give it some gas and the whole truck shakes back and forth and backfires. if i keep on the gas a little long enough it settles down  but stall as soon a i put it in gear any ideas?

Title: Re: est timing issue looking for shorts
Post by: Captkaos on November 15, 2012, 06:15:40 pm

Did you set the timing to 0 with the wire disconnected?

Title: Re: est timing issue looking for shorts
Post by: rusty but trusty on November 16, 2012, 05:56:35 pm

yes i set the timing exactly to 0 and i have replaced ignition module

Title: Re: est timing issue looking for shorts
Post by: bd on November 16, 2012, 08:12:31 pm

Did the problem exist before you set the timing?  Was the timing very far off when you set it? 

Edit:  Was anything else changed or repaired?

Title: Re: est timing issue looking for shorts
Post by: rusty but trusty on November 16, 2012, 08:54:17 pm

the problem has exsisted since i bought the truck but i found a intresing crimp in the wiring conecting the injectors to the eletronic spark module

Title: Re: est timing issue looking for shorts
Post by: bd on November 16, 2012, 09:51:56 pm

That IS interesting, since the EST module should only have ground, ignition, ECM and Knock Sensor connections on a TBI engine.  However, the pink/black wire connecting to the EST module splices with the red wire and white wire connecting to the two injectors, as well as other pink/black wires; and then collectively they connect to 12-volt ignition power.