Neutral safety switch and fuel gauge on 98 swap

haha same issue in my 98 vortec. the motor is in an runs sounds sick. im using the 5.7 liter vortec fuel pump i was also told the 4.3 pump wouldnt be enough but the 5.7 would be? the only way i can start my truck is to use a jumper wire and put it on the starter soleniod wire. it wont start by key... my tranny is a t-56 though... the tach doesnt work so im not sure if allen needs to redo my PCM and change it to a 3 or w/e it needs to be... ill be bummed if i have to send it back and not even get to use it yet lol... like you said the swap wasnt bad but the wiring is frusterating me... i have no idea what the deal is.... good luck guys im going to start it one way or another this weekend.

The wiring would have made me throw the truck away, thats why I gave it to Allen.. GL with it

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Originally Posted by ChevyLee

The wiring would have made me throw the truck away, thats why I gave it to Allen.. GL with it

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well it really isnt all that bad the worst part is having 2 harnesses in the truck right now its SO cluttered i cant wait to get rid of them. but honestly all there really was to hook up was the fuel pump,battery,ignition,ground,reverse backup light(didnt bother) and neutral position switch wire (for auto trannys) and then the PAIN IN MY ASS starter solenoid wire... i dont have a damn clue what the problem is... i may have to call NP and see if they can help. i dont believe its anything to do with the harness but maybe they can help me trouble shoot... i just dont get it... everything else seems to work. and the truck runs... cam sounds good need to weld up my exhaust so i can actually hear it lol the manifolds are damn loud. i have a question for you guys though.

does anyone know for sure if the 5.7 fuel pump will supply enough fuel pressure at WOT to not starve the motor? it seems to run fine and when i rev it its really really snappy, very quick and responsive.

oh and also. the 02 sensors i was planning to use i pulled off the 5.7 vortec as well the plugs are exactly the same as the 5.3 harness is this a safe thing to do or not such a good idea?? they seem to be in great shape. i already welded the bungs into my Y pipe i just need to figure out wether these will work fine? thanks guys

The V8 Vortec pump should be fine.

The reason the starter may not be working is you may have cut the wire that fed voltage TO the starter relay when you disconnected the wiring harness from the original engine. Every relay has four basic connections, ground, trigger voltage, power in and power out. See which of these is missing. The starter relay may use the ground as a triggering device for the relay, if so then the power to the relay could be jumpered off of the power input from the battery to the relay making it more or less a 3 wire setup.

wtfan, what neutral safety switch wire did you hook up to where? All I did for the tranny: I took the wires that were on the original harness and went from the tranny into the cab by the blower, and I spliced them into the 5.3 harness right by the tranny. I didn't know what else to do, as I didn't know what any of them were for

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Originally Posted by oneBADDz

wtfan, what neutral safety switch wire did you hook up to where? All I did for the tranny: I took the wires that were on the original harness and went from the tranny into the cab by the blower, and I spliced them into the 5.3 harness right by the tranny. I didn't know what else to do, as I didn't know what any of them were for

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well could the ground to the starter relay be causeing this. because ive traced all other wires and they are fine... the ground is the only one i havent traced to the end. i didnt cut any wires when i disconnected the harness from the other motor. but... i will recheck everything again.

i know i have a constant 12v
i have the trigger power
i cant get power out(purple wire)
and ill have to check where the ground goes and see if its hooked up. i hope thats not the issue or ill be pissed!
how would i go about jumpering the power input

i didnt hook up a neutral safety switch because jonathan at NP said it was for auto transmissions im running the t-56 what is in yours?

On the relay connections, when you hit the ignition key will it light up a test light on any of the connections? You've probably removed the ground wire for the relay circuit when you disconnected the engine wiring harness. Run a wire from the battery or chassis ground to the relay and then try it.

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Originally Posted by RedHeartbeat

On the relay connections, when you hit the ignition key will it light up a test light on any of the connections? You've probably removed the ground wire for the relay circuit when you disconnected the engine wiring harness. Run a wire from the battery or chassis ground to the relay and then try it.

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yeah when i crank the igntion the small pink wire with black stripes gets power. the orange is constant power. small black must be ground and the purple is constantly dead which is the problem. but not grounding the relay might cause the relay to not complete the circuit? well ill try and run a ground from the battery to the ground on the relay. ill totally flip my S*** if this is the problem. ill kick my own A** lol.

It really sounds like your problem is the ground. Mine however isn't. I did realize that when it's running the security light stays on. I didn't think that would happen since I left the stock computer as well.

mine did to, it turned on an off. You can just take the bulb out of the dash to fix that.