lt1 to ls1 swap no start
I get no fuel pressure and i also get no power to the starter. i dont here it engage and the fuel pump i dont here it prime.
I dont have VATS disabled. Can that be the main issue?
Does that stop the starter from getting power? or engaging.
I dont think i have the fuel pump wired correctly.
The harness i bought has its own fuse box for the fuel pump relay and the ignition.
for the ignition i have the red wire for key on cracking to connector C100 cavity G(Power feed from igntion Fuse #11).
as for the fuel pump relay i have the #87 wired to connector C220 to the Cavity J (Fuel pump relay control).
i dont have no wire to the #30 on the relay(+12v).
I am really confused at this point why im not getting any power to the fuel pump and the starter.
This is my 1st car project. hopefully this made some sense.
Thanks for the help fellas
From what we have discussed it sounds like the company you paid to wire it took your money and left you hanging... I say that because there are several of us that have built direct plug in Harnesses for this swap that start the car without issues.
I would put a foot in their *** and ask them why they couldn't build a proper harness.
I get no fuel pressure and i also get no power to the starter. i dont here it engage and the fuel pump i dont here it prime.
I dont have VATS disabled. Can that be the main issue?
Does that stop the starter from getting power? or engaging.
I dont think i have the fuel pump wired correctly.
The harness i bought has its own fuse box for the fuel pump relay and the ignition.
for the ignition i have the red wire for key on cracking to connector C100 cavity G(Power feed from igntion Fuse #11).
as for the fuel pump relay i have the #87 wired to connector C220 to the Cavity J (Fuel pump relay control).
i dont have no wire to the #30 on the relay(+12v).
I am really confused at this point why im not getting any power to the fuel pump and the starter.
This is my 1st car project. hopefully this made some sense.
Thanks for the help fellas

What I highlighted in bold is what confuses me. What did you wire to Cavity G?
No power to the Fuel Pump is because there is no 12V source in on 30, there needs to be a 12 Constant in on this, 87 out to the Pump, 85 ground, 86 the 12v FP Relay Control wire from RED 9 on the PCM.
But, don't worry about what I just said, my question is why is the factory Relay not used?? It works good from the factory and in every harnesses I have built so I want to know what dip **** put that in the harness with their wisdom in turn leaving you hangin looking for answers here from some of us technical experts.
Send me that damn harness and get your money back from the company that built that crap. They have any questions on how to do it the RIGHT way they can get ahold of me for lessons.
I'm tired of seeing these damn companies doing half-assed ****.
As far as the other stuff I'm baffled because as I mentioned these harnesses are a direct plug in swap. There is no need to wire ANYTHING unless it's a 1993-1994 and you have to put in the OBD2 DLC.
dude didn't even want to help out. He basically said did you read the manual we sent you. But in a pissed off manner. At this point I will try my best to figure it put. Thanks all for the recommendations.
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basically there is two wires that i believe go there plus the battery wire to the starter. the dash lights work. headlights work. i will have to check the brake lights today.
What I highlighted in bold is what confuses me. What did you wire to Cavity G?
No power to the Fuel Pump is because there is no 12V source in on 30, there needs to be a 12 Constant in on this, 87 out to the Pump, 85 ground, 86 the 12v FP Relay Control wire from RED 9 on the PCM.
But, don't worry about what I just said, my question is why is the factory Relay not used?? It works good from the factory and in every harnesses I have built so I want to know what dip **** put that in the harness with their wisdom in turn leaving you hangin looking for answers here from some of us technical experts.
Send me that damn harness and get your money back from the company that built that crap. They have any questions on how to do it the RIGHT way they can get ahold of me for lessons.
I'm tired of seeing these damn companies doing half-assed ****.
Last edited by davidc212k; Mar 11, 2014 at 08:25 AM.
I believe if i install that. it should take care of the fuel pump issue.
what worries me is the two connectors that i have plugged in the starter and then the red(+) coming from the battery to the starter.
As for the ignition wire that says ignition wire to key on and cranking power. like i stated i have it plugged in the C100 Connector Cavity G Pink wire(Power feed from ignition fuse#11.)
There is no wires for the ignition relay for #86,#30,#87 or #85. So how am i suppose to get ignition ? lol.
I feel like i should just plug in the factory wires to these two relays. lol.
Last edited by davidc212k; Mar 11, 2014 at 10:36 AM.
As for red wire on the psi harness, on the LS1 C105 Cavity B its for the ignition one voltage that gives 1 voltage when the key is on cranking.
On the LT1 C105 its for power feed from fuse #10.
Last edited by davidc212k; Mar 11, 2014 at 01:49 PM.
on the C100 Cavity G Pink power feed from ignition fuse 11. Is that the ignition key on crank?
There is also the Pink on C105 that power feeds from fuse#10.
I do get power to the gauges. i did notice last night.
i dont get anything on the milage or the tachometer.
I will take a video shot of it all. Soon as i get off work.
I swear i cant concentrate at work, lol. been thinking about this issue all day.
Now i get ignition to the starter.
As for the fuel pump i connected the #30 and the #87 from the fuel relay to the connections on the factory connections.
I get not fuel pressure and priming sound.
now i just need to get the fuel pump running.
This C100 G Wire is a 12v with key on, Fuse #11 in the box is this circuit, that would have originally have powered the Opti on the LT1. This circuit is adapted for another use in this conversion, as are a few others.
Lights and all that are going to work, it's chassis wiring on completely different circuits.
Now I will say this..what you "believe" you should do is probably not going to work. You don't sound like you have a lot of wiring knowledge and before you burn the car down I recommend that you take a step back here and think about how you want to go about fixing this.
I honestly think you have a pile of **** for a wiring harness that needs to be looked at to ensure the quality, but that is just me.
.


i will try my best to get this car running without causing any fires. lol.
last night i wired the FP relay #30 for 12v and the #86 to the fuel pump. Like stated i got no fuel pressure or prime from the fuel pump.
The harness has a #87 that is going to PCM for the FP relay Control.
The harness also has the #85 for ground built in the harness that is going to ground by the passenger side.
This is a learning experience. So i did a bit more research. i will test the 12v source for voltage.
I was curious, since i dont have a wire connection to the oil pressure sensor wired to gauge cluster. Does that send a signal to the PCM to cause the fuel pump not to power on?
The harness did come with a oil pressure connector for the LS1, but since im using the LT1 body n gauge cluster. that wont work.
I simply have to wire the oil pressure sensor wire to the LT1 gauge connector.
Im just taking a wild guess if that can cause no power to the fuel pump.
Thanks for your grateful help gents.
Last edited by davidc212k; Mar 12, 2014 at 01:10 PM.






