Another one for that book

[348tripower]

A buddy of mine has been chasing problems with his 1991 k1500 5.7 throttle body engine for about a year. I have asked some questions here and given him the info. Still not cured.
 Last weekend he took all the injection stuff off and piled it up. He put on a 600 edelbrock and intake. He fired it up and drove to my place. It was still doing the same thing. Random missing under load.  :?  I went to my cabinet and pulled out the test light, some number 12 wire and ends. I went to the fuse panel and found a hot in run and start and pulled the wire to the coil in the distributor.
Cured
My question is, does the pink wire that fires the coil come out of the computer?  I think there is a wiring problem as he had also swapped the computer out.
Anybody?
P.S. I will add this to the stuff to check list :oops:

[enjenjo]

My question is, does the pink wire that fires the coil come out of the computer? I think there is a wiring problem as he had also swapped the computer out.
Anybody?

I can't speak to that truck in particular, but when retrofitting fuel injection to an older car, it's one of the few wires from the original harness that is still used, and does not go through the computer. It is fused, and I have seen problems with a defective fuse, and bad connections at the fuse block.

[wayne petty]

swap out the ignition switch...  bet you will find a burned contact when you open it up... here is a pin out..




I1 runs the ignition and many several other ignition related circuits..

A is accessory... runs other devices..

both I1 and A and S are powered by the B1/B2 wiring..

I3 is usually a few items that are NOT ON while cranking.. the AC system power usually...  its powered by the B3 circuit..

G1 and G2 actually connect to ground while cranking...  they are connected to the OIL PRESSURE LIGHT  and TEMP LIGHT circuit as a bulb check...
but knowing they are there is neat... as one with a hot rod could also use them for bulb check by wiring them into the sender side of the lamp circuit..  as long as the column is properly grounded. as most are...

by the way... AZ stores and wells have replacement connector bodies and terminated pigtails to replace burned wiring ends...

~~~~~~~~~~~~~~~~~~~~~~~~~


look at the burned area which is in the RUN position...



here is a 91 TBI wiring diagram... i know the system is removed...

[wayne petty]

just for those who follow along...

some point type ignitions applications have an I2 terminal..

this is the bypass circuit..  instead of the wire from the starter solenoid R terminal.. there is a NON RESISTOR wire to the coil positive in parallel with the resistor wire from the I1 terminal...

in those and most others.. the I1 circuit OPENS in the cranking position... so power has to flow from the ignition coil from the I2 terminal if you want the engine to start while cranking..

on those... when converting to HEI or other... you can tie the I1 and I2 wires together usually... these are usually NOT CHEVY applications.. buick olds pontiac..  if the points type GM or other car that uses this switch.. does not have an ignition bypass circuit from the starter solenoid.. it will be wired this way...



for dash mounted GM style ignition switches...

when converting to electronic ignition.. swap to the 75 chevy van dash mounted ignition switch.. available in almost every parts store..  please don't try to run the heater blower power through either the column mounted or dash mounted switches.. use a relay for that circuit.. switched off the ACC circuit..

[348tripower]

Ok, Now we will get into checking that switch. This would be the second of this problem I have run into. Symptoms were the same. Thanks Wayne