454 tbi questions

[ryanroo]

spec on a 454 TBI is 26-32psi. they run higher than small block tbi. so it is in spec as far as i am concerned. half a pound isnt enough to make it run poorly and the guage could be inaccurate by that much.

also there are no vacuum leaks that i can find.

i am still leaning towards injectors
Ryan

[Bill usn-1]

Some of the later 454's did run higher pressure to allow the use of the smaller SBC injectors to run the BBC.

So you have to make sure the spec matches the year.

If the TBI is all original with stock injectors and regulator then your probably fine.

Early BBC TBI used larger injectors at the lower pressure.

[ryanroo]

the entire TBI injectors and all came from a 94 c3500. by all appearances it looks good. the truck they came off of was in very good shape.

is there a wat to determine the PPH of the injectors themselves? could it be a complication of the higher pressure and an ECM that is firing injectors more than required? the calpack or whatever?

Ryan

[Bill usn-1]

I have a few injector charts but mostly for the older stuff.
Look for some inj service places like injectorman or something on google.
They will list replacement injectors and sometimes list the specs.

You said you have an older ECM so the BPW and fuel tables may be off for those injectors. You would need to get it running and log data to see how far off the fuel is.

Some adjustment to the regulator may help if off or just commit to tuning it.

[ryanroo]

I had a good friend of mine who is much more experienced and also has a scan tool, come look it over with me today. the scanner shows no codes again.

he looked at the injector spray and confirmed what i thought. the spray is to wet and he pointed out some stuff that i hadnt seen because i couldnt keep the truck idling long enough by myself. the injector pattern is a little funny and the are dripping slowly. i will try new injectors and hopefully then it will at least idle and we can get some more data with the truck in closed loop for a longer period of time to so if i need to have a chip burned i can have some data for the person who does that
Ryan

[ryanroo]

new injectors, same problem. except now it wont start itself very well at all. seems like its not getting enough fuel at idle/startup. i know the ECM is getting a crank signal. i am going to call some places monday and see if any of the experts/chip burners have any ideas if the programming for the early computers is not compatible with the newer TBs
ryan

[Bill usn-1]

Are you sure your voltage is good while cranking?
You may want to check your 12V (red/orange)and switched 12V (pink-blk stripe) during cranking.

[EagleMark]

Originally Posted by Bill usn-1

Some of the later 454's did run higher pressure to allow the use of the smaller SBC injectors to run the BBC.

Well I didn't know that, learn something new each day! The only later model years I have seen actually had larger injectors then earlier ones...

[ryanroo]

Originally Posted by Bill usn-1

Are you sure your voltage is good while cranking?
You may want to check your 12V (red/orange)and switched 12V (pink-blk stripe) during cranking.

the entire system has sufficient voltage. i have not checked that those wires in particular have 12+volts recently, but we checked all of the pinouts for correct voltage earlier in the diagnosis process. i cant say as we checked during actual cranking for any other than the crank signal wire. i am confident in my wiring though. that is one step that i took plenty of time with, both the FI harness, and the complete rewire of the truck. all of the wiring is above average IMO. all splices soldered, and all of the used harness was inspected for flaws, and opens. i replaced any problem areas, although there were only one or two. the battery voltage guage holds at 12+ when the key is on, 14.5+ running. the battery is brand new as of july, and has not been abused.

[ryanroo]

after talking to a fellow in the TBI industry, i tried removing one of my fuel filters, i had one before the pump and one after thinking i was doing a good thing. he said that it was likely restricting flow. after removing the extra filter there was no change. i did the entire Iac relearn procedure, atempting to get it to idle, and still no dice. same exact issues. trying to drive it is a joke because of course it wont idle, but it falls dead on its face with load. it will move itself in low gear and reverse, and in second it will try to move, but to hasty of throttle movement or not enough clutch slippage will kill it instantly. still seems like a fueling issue of some sort to me

i am about to re install the dreadfull q-jet on it. or just light the truck on fire and dance around it like a nutcase.

ryan