5.3L into Jeep CJ8 Scrambler

[CHIEFWAHO]

Ok need some help.
I am putting a 5.3 into a 1983 Jeep CJ8 Scrambler.
The motor I bought is from another fellow jeepers project that didn't get off the ground.
I was told the motor is from a 2004 Tahoe 1400 miles (I have verified).
Adkins 4x4 Siloam Springs, AR is where it came from (2 to 3 years ago).
They rewired the harness and flashed computer, only sensors left (2) O2 and MAF.

This is the list of the 5 wire hookup on the motor harness:
I know colors probably don’t mean much, but here goes:
Brown – Alt Light or gauge
Pink – Key Hot (maintain 12V while cranking)
Green – Battery Hot all the time
White – Tach
Purple – Starter
(I am also using a complete Painless 12 circuit Jeep CJ harness)

Using Walbro 255 fuel pump.

Finally turned the key today and it cranked and fired but will not run more than a couple of seconds. My inline fuel pressure gauge at the rail shows 52 and drops to 45 to 46 while trying to start. Is this normal? Or should the pressure be higher? Or is there something else I am overlooking. Thanks in advance for any suggestions.

Link to my build thread:
(have posted progess as of late)
Trail Scrambler Build/Rebuild-Chiefwaho - Jeep Scrambler Forums & Discussions

[RedHeartbeat]

Sounds like the PCM needs to have the VATS(vehicle anti theft system) turned off disabled.

[CHIEFWAHO]

Sounds like the PCM needs to have the VATS(vehicle anti theft system) turned off disabled.

Its supposed to. I have been trying to contact Adkins to verify what exactly they did to the computer. They say they test every motor before it leaves their shop.

Does the fuel pressure seem within range?

[RedHeartbeat]

the engine will idle on 15 psi. You have a problem with your VATS tune I am 99.9% positive. I loaded HPTuners version 2.22 the other day and my truck won't run with an upload from it, does exactly what you're describing. I downgraded to 2.20 and reloaded my tune and the truck started right up.

[CHIEFWAHO]

spoke with Adkins, they said the VATS is disabled.

He thinks the injectors are stuck. This motor has sit for 2 to 3 years. This sound logical?

Should I try one of those DIY injector cleaner kits that attach to the fuel rail? Or pull injectors and clean manually.

Is there a good write-up on how to clean injectors manually?

[RedHeartbeat]

Think about it for a second, it starts and runs for a few seconds. Injectors cant be stuck.

[CHIEFWAHO]

MOTOR NOW RUNS!!!!
I am idiot, still learning!
I was not maintaining 12V while cranking,
found a wire that did and presto it stays running.

Thanks for the help/suggestions,

[RedHeartbeat]

Ah hah! Eureka! Don't you just hate it when its operator malfunction!

[CHIEFWAHO]

Ah hah! Eureka! Don't you just hate it when its operator malfunction!

yeah it is a learning experience, but I can't wait to put one of these in my 1981 Chevy C10 Short/Wide.

[team39763]

Cool...I want to try swapping one in a CJ sometime soon. You'll love that 81 C10 once you get it swapped. Mine makes me smile everytime I drive it.