Author Topic: Test fire help!  (Read 1283 times)

Offline Niceandeasy

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Test fire help!
« on: April 15, 2019, 09:30:14 PM »
My boss said I can have a junk plow truck we have at the back of the work lot. It’s a 92 gmc 1500.  My question is how to test to see if motor is good.  He lost the keys and it’s tbi. How would I get this thing to fire off with no keys. Just want to see if motor is good so I can take the 350 and swap out my 305 in my 87.

Offline Rapid Roy

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Re: Test fire help!
« Reply #1 on: April 15, 2019, 09:32:20 PM »
Welcome
1974 Cheyenne 10 LWB STOCK 350 W HEI /TH350/AC/4 BBL Quadrajet
Mopar by Birth
Chevy by Choice

Offline 75gmck25

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  • 1975 GMC K25 Camper Special, 350/TH350/NP203
Re: Test fire help!
« Reply #2 on: April 16, 2019, 05:27:27 AM »
If the column is the same as a square body, there is a wide, flat plug near the base of the steering column with about 7 wires in it, and that is where the actual ignition switch is located.  The key up on the column just pulls a rod that actuates the switch on the lower part of the column.  The plug has the turn signal wiring also, so only about 2 or 3 wires are for the ignition switch.

If you can figure out the color code of the wires, you can unplug the wires and jump between wires to make the same connection as you do when you turn the key.  You need to provide constant-on 12 volts to power the truck, and then momentary 12 volts to turn over the starter.  You could also do the momentary-on by jumping across terminals at the starter.

Bruce

Offline JohnnyPopper

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Re: Test fire help!
« Reply #3 on: April 16, 2019, 11:18:28 AM »
Easier to hammer a flat blade screwdriver into the ignition, break the lock, and turn.

These trucks are easy to steal...  >:(
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction