5.3 swap into 78 k5

[beast_olds]

ok, need input. swapped a 5.3 into a 78 k5 blazer used the th350 trans, tbody is iac , pcm is a junkyard one supposedly from 01 Tahoe part #12200411, engine is 2003 Yukon, injectios and rail are from 07 sierra denali lq9, new cmp and ckp sensors, harness from modern vintage, disabled vats. problem I have is it wont start, I have tested and have 55-60psi fuel pressure, spark and injector pulse. however while spinning it will "hit" occasionally but never start up, but if I spray carb cleaner in the t-body it will run, if I keep it running with the spray for 3-5 seconds it will continue to run under its own power like normal. if I shut it off then try to restart it immediately it will. but if it sits for 5-10min wont restart. any ideas? thanks

[5FDP]

If that computer for a drive by cable though?

I thought many tahoe computers after 2001 or 2002 went to drive by wire but I'm not certain on the year.

If the injectors you installed are not correctly put into the tune you are going to have issues. Stock injectors are 24lb/hr on a tahoe if non flex fuel and those are larger you need to correct for that. Did they come from a sierra classic or the NNBS sierra's with the 6.2's??

Post the tune and a log file.

[lm7s10]

You need to confirm if the ecu is capable of running an iac and tps. If you're using a new dbw ecu with a dbc throttle body, you'll need to segment swap from a dbc ecu (express vans were the only ones to run a dbc ecu through 03 I believe). AND the harness will need to be re-pinned to accept an iac and tps if not already. LT1swap.com has this info on his page.

[beast_olds]

the injectors came from a lq9 6.0 sierra denali classic