Author Topic: Blown fusible link  (Read 14162 times)

Offline 2013DartR

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Blown fusible link
« on: April 23, 2015, 04:28:38 PM »
I had the fusible link burn out on the double wire coming off the junction box on the firewall. I have search almost everywhere and can't find a short. Any ideas? Attached is a picture of the wire I'm talking about.
81 Chevy K-10 305, Holley 4175 carb, with an 85 700r4 trans

Offline bd

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Re: Blown fusible link
« Reply #1 on: April 23, 2015, 06:50:03 PM »
Was it burned apart or broken apart?  It appears simply broken in your image.
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline 2013DartR

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Re: Blown fusible link
« Reply #2 on: April 23, 2015, 07:12:14 PM »
It was burnt apart. When I turned the ignition switch, the engine would not turn over and started smoking that link. I replaced it with another I got from the junkyard and did the same thing. When testing the wires for continuity to ground, only one wire has continuity but it is only when I to turn ignition switch to run.
81 Chevy K-10 305, Holley 4175 carb, with an 85 700r4 trans

Offline bd

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Re: Blown fusible link
« Reply #3 on: April 23, 2015, 08:09:56 PM »
Did it begin to smoke in the ignition switch run position or not until you attempted to crank the starter?

What year/model truck?  Is it your 81 K10?

Check the purple wire connecting to the starter solenoid.  Look for burned or chaffed insulation where the wire runs from the solenoid to the short, tubular steel elbow (heat shield conduit) located at the back lower corner of the block.  The wiring is prone to damage there because of the extreme heat radiating off the exhaust manifold and poor air circulation.  Also, assuming HEI, look for a damaged ignition feed wire (12- or 10-gauge pink) running between the firewall bulkhead connector and the distributor B+ terminal.  Pay particular attention to anyplace the wiring makes a turn around metal objects.

If you don't find anything obvious, pick up a ~15-amp auto reset circuit breaker (image) and attach a couple of 18" long, 16-gauge test leads with insulated alligator clips and temporarily substitute that for the fusible link while troubleshooting.
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline 2013DartR

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Re: Blown fusible link
« Reply #4 on: April 24, 2015, 05:11:33 AM »
Ok, I'll check that stuff tonight. As for the smoking, I'm not sure I'll have to check that tonight as well. I'm thinking it starts smoking when I try to start it but not sure. It is strange that when I turn the key to the run position I get nothing, no buzzer, dash lights, etc.
81 Chevy K-10 305, Holley 4175 carb, with an 85 700r4 trans

Offline bd

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Re: Blown fusible link
« Reply #5 on: April 24, 2015, 08:30:20 AM »
It is strange that when I turn the key to the run position I get nothing, no buzzer, dash lights, etc.

The 'link' is a fuse....
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline 2013DartR

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Re: Blown fusible link
« Reply #6 on: April 24, 2015, 08:14:19 PM »
Okay, I did a lot of wire tracing tonight. Finally found a bare wire on the back side of the engine by the transmission dipstick. Thanks for the good advice. I got everything back together and working again.
81 Chevy K-10 305, Holley 4175 carb, with an 85 700r4 trans

Offline bd

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Re: Blown fusible link
« Reply #7 on: April 24, 2015, 09:28:34 PM »
Happy to hear it!  Glad to help.
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)