Tapping the FSS Wire

crash-harris

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Somehow, every form of search had failed me, so here I am again, trying to find a good spot on the FSS wire to tap into for my fuel pump relay (electric lift pump install on Thumper). Instead of cutting the terminal off on the IP side and crimping on a new one with yet another wire jammed in it, if like to find some other place to tap into it or a nearby 12V source in in the start and run key positions. Isn't there one of these 12V sources at the GP relay?

Thanks in advance, all.
 

crash-harris

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Thanks Trike!

Isn't the red/green stripe the alternator trigger? I've converted to a 3G alternator (actually swapped/robbed my conversation from the crew cab). I thought all the FSS wires are solid red 10 gauge? It's been a long time since I dug the one on the crew cab out to tap it, but it's buried too far to see in the sun/cold, which is all I get after work anymore.
 

ROCK HARVEY

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In post #9 of that other thread franklin2 posted a wiring diagram that shows that the fuel heater wire is another option for “key on” power.
 

crash-harris

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In post #9 of that other thread franklin2 posted a wiring diagram that shows that the fuel heater wire is another option for “key on” power.
I noticed that. I was not able to get my filter head heater to seal on this truck for some reason (never had issues with the crew cab), but it's like to find one at the rear of the engine (#7 cylinder area). Whenever I install an electric lift pump, I also install a 3-pole oil pressure switch to trigger the fuel pump relay, as a safety switch. Since this truck has a Banks Sidewinder, I'm splitting the turbo oil port for the oil pressure and will already have wiring and loom running that direction, versus the front of the engine.
 

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That red wire with the green stripe goes directly past the #7 cylinder on its way from the firewall to the shutoff solenoid on the IP. The fuel heater wire might go the same route, but I’m not sure.
 

crash-harris

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Thank you both. I looked over some more schematics last night and there are actually multiple red/lt green wires on the IDI equipped trucks, only just the one for the charging circuit on the gassers.
 
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