98 k3500 driving me insane. Wiring harness issues

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Hey All new member here.
I live these gm400t trucks so I will save one when I can. I purchased av1998 k3500 4x4 crew cab with no motor and no wiring harness. I then picked up an engine and harness from a 98 k2500 ext cab.
I installed it and can't get the truck to run
If I spray the intake she will fire but I get no power to the original fuel pump harness left on the truck and is running up to the firewall. New harness seems to have a 4 plug square running to the back of truck with orange,grey,purple,black wires orange is D and hot I do not get 2 sec prime power from any other wires I'm lost.. also I'm using the original 3500 ecu and if I jump the relay u can hear pump but sounds like the intake is just pouring gas in it I don't know what to do next. Any help would be appreciated
 

red98

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Hey All new member here.
I live these gm400t trucks so I will save one when I can. I purchased av1998 k3500 4x4 crew cab with no motor and no wiring harness. I then picked up an engine and harness from a 98 k2500 ext cab.
I installed it and can't get the truck to run
If I spray the intake she will fire but I get no power to the original fuel pump harness left on the truck and is running up to the firewall. New harness seems to have a 4 plug square running to the back of truck with orange,grey,purple,black wires orange is D and hot I do not get 2 sec prime power from any other wires I'm lost.. also I'm using the original 3500 ecu and if I jump the relay u can hear pump but sounds like the intake is just pouring gas in it I don't know what to do next. Any help would be appreciated
Which engine did the truck come with, what donor engine are you using? The more info you post the more likely to get a solid answer.
 
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Yes I have nothing until I jump the relay then I get pressure inside of the fuel rail which pushing the button allows the fuel to come out it comes out high pressure But at the same time it sounds like I have a broken line and gas is just pouring in to the intake whenever I jump bypass the relay
 

RichLo

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I would fix the fuel spraying issue first, that seems like a more severe issue than the fuel pump wiring for now. Take the top of the intake off and see whats going on in there.

For the wiring problems, I assume you have tried a known good relay already?
 

smokymtn65

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pull rubber line at fuel pressure regulator and see if gas is running out if so its failed.
 
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I would fix the fuel spraying issue first, that seems like a more severe issue than the fuel pump wiring for now. Take the top of the intake off and see whats going on in there.

For the wiring problems, I assume you have tried a known good relay already?
Yes have tried 2 different relays what is the possibility of the fuel lines being mixed up. They put them at the back of the motor on drivers side and have to be screwed in is it possible to mix them up or are they different sizes?
 
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