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This is my first full engine build i work with a guy that has a full machine shop rebuilding engines he did the machine work besides the line bore and he showed me how and what to do to assemble it was alot of fun the build consist of
4.125 bore
Molnar rods
DSS pistons
balanced rotating assembly
heads sent off to lingenfelter for porting, milled, valve job and .660 lift springs higher compression at 12.5:1
Katech oil pump
BTR 225 cam
BTR Trinity truck intake
NW 103mm throttle body
speartech harness and e92 computer
so now on to the not so fun part we have it on the run stand and we can't get it to fire up so fast we have gotten it to run with a little help of starting fluid but it will only crank over and then try to fire and instantly dies i have called speartech and they think it's voltage i made sure the ground are good fuel pressure is dry to 80psi out of the pump what else is there i can do to check
Last edited by Minol-L8T; Dec 4, 2024 at 07:33 PM.
Reason: Spelling
Nice pipes.
Guessing it's going in a boat ?
What you using for crank position sensor ?
58x on inside, or external crank trigger ?
Thanks no it's going in my rock crawler I had a similar setup with the 5.3 took some hooker blackhearts and flipped them upside down to clear the chassis and wont get smashed it has the 58x inside crank trigger
Why you wanna KRAWL with a 103mm Throttle body and 12.5 compression ?
A stone stock motor, with stock truck manifolds would work better, and go farther and burn 87 octane.
.
.
. That out of the way:
What is fuel rail pressure while engine is CRANKING ?
THREE wires to crank position sensor:
Do you have 5 Volts ?
Do you have GROUND
Do you have crank signal ?
. Are both injector banks getting power from their respective FUSES ?
Why you wanna KRAWL with a 103mm Throttle body and 12.5 compression ?
A stone stock motor, with stock truck manifolds would work better, and go farther and burn 87 octane.
.
.
. That out of the way:
What is fuel rail pressure while engine is CRANKING ?
THREE wires to crank position sensor:
Do you have 5 Volts ?
Do you have GROUND
Do you have crank signal ?
. Are both injector banks getting power from their respective FUSES ?
Last year I got into more of a racing type of rock crawling where it's not so much crawling more like bouncing thru the rocks and I want to do some door to door racing my 5.3 was going up against some heavy hitters everything from turbos, supercharger and ever couple of prochargers so I need to up my game so that's why
fuel pressure stayed the same at 80psi while cranking
yes 3 wire plug on the crank sensor
2 grounds 1 in the harness going to back of the passenger side head and the other from the battery to the block and the other things are things i will have to check thank you
I do NOT do this for a living.... so, we'd BOTH best defer to any professionals on this.
Observations:
1) 80 PSI static fuel pressure is rather high... I'd get a return fuel pressure regulator in there right damn quick, vacuum referenced. I play mine at 58 PSI static.
2) I'm going to wild *** guess that you have no TACH signal from PCM- check to confirm- IF PCM doesn't see engine turning, it's won't trigger injectors. ( Noid Light ?)
I do NOT do this for a living.... so, we'd BOTH best defer to any professionals on this.
Observations:
1) 80 PSI static fuel pressure is rather high... I'd get a return fuel pressure regulator in there right damn quick, vacuum referenced. I play mine at 58 PSI static.
2) I'm going to wild *** guess that you have no TACH signal from PCM- check to confirm- IF PCM doesn't see engine turning, it's won't trigger injectors. ( Noid Light ?)
Me either this is my first full build everything I have read has said the gen v hpfp if running a inline fuel pump and regulator to set it at 72psi all of this are good things to check thank you
I started my L83 on an engine stand with a used corvette filter, so 58psi, started and ran fine. Are you sure VATS is off? There are a couple of them that have to be done and the starter diag has to be turned off.
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L8T wont fire 
