TBI, electrical nightmares, project ideas anyone?

[Sean in NE]

OK, got a interesting build/project, and usually a pain, but nonetheless should be fun when done. Heres the main project, 1989 GMC R3500 dually crew cab. It has the TBI electrical harness in the engine compartment, with a missing 454. I have yet another thorn in my side that I thought would be a good idea, so I hope its worth it in the long run. My donor truck is a 1981 Chevrolet K30 regular cab. Going to do the whole 2wd to 4wd conversion, by using the front end of the 81, and splice it into the crew cab dually frame. Luckily the 81 has a 454, but has a carburetor. Also both trucks have the granny lo 4 speed transmissions.

The PO had done some chopping, and adding of wires and circuits, for lights, CB radio, I don't know. And they didn't do the best job of removing the engine harness without doing some snipping here and there. My question is what is going to be easier in the long run to getting a fuel injected system going again in something like this? I've seen universal harnesses available for the entire truck, or certain harnesses here and there. So I don't think that's going to be a major issue.

Really how much better is a 454 TBI over 454 Carbureted going to be?  I've thought about gutting the wiring, put in a universal harness and run the 454 and holley carb thats on it, and be done. But then, how much does that ECM control in the vehicle? It has cruise control. Air conditioning. Electric helper fan. Fuel pump, the throttle body injectors of course. And does a 1989 have ABS of some sort? Think my 1990 V1500 Suburban had something to that nature.
Thats just electrical, how about mechanical? Seen a special camshaft for a EFI 454? Is that needed for TBI? Especially if I use the 454 from that 81? Not to mention I need to buy most of these components; throttle body, distributor, sensors, etc. Only thing I have is the ECM. But then the PO hands me another ECM and said "this one came from the truck". Wonderful LOL. Which one works now LOL. Venting sorry.

Ugh, I just loooovvvvveee electrical when someone else took things apart LOL. Who has a great electrical schematic book out there on the market? Suppose I should pick one up and see what else is diced up lol.

What is going to be a better route to go in? Carburetor, GM TBI, or an aftermarket EFI such as Holley, FAST, MSD, etc.  I may have bit off more than I can chew with this truck. Or at least what makes the engine run. Thanks in advance!
PS, I don't have many pictures, but can post some later.

[fitz]

  Tough call trying to decide between carb vs fuel injection. Both have advantages to them.
   I've had a few 454 TBI motors and have had great luck with them. You have done your homework as far as figuring out what you will need to get a TBI system up and running..
  Are there any junkyards in your area that you could get the wiring harness & TBI unit from?. You could easily spend about $2,000 buying the stuff new (Painless wiring harness, Holley TBI unit, fuel pump, & all the sensors etc...).              All of the aftermarket fuel systems you mentioned (Fast,Holley,MSD) will easily set you back about $2500 once you but the required fuel pump for the system.
  If it was me, I would be tempted to run the 454 carb set up that you have ( although I'm a huge Edelbrock carb fan).  Sounds like your 81 k30 will have most of the parts you need to do the swap. As far as hooking up the cruise control, that's above my pay grade ( I would leave it disconnected myself). You may give up a little mpg's with the carb, but nobody build a big block crew cab 4x4 for the economy.  In my eyes, the carb will be an easier swap and save You alloy of $$.

[bake74]

     In my experience of doing machinery every day with a lot of PLC's & computer electrical, if someone else torn into it and started hacking wires, it is easier and takes less time to just rip everything out and start over.
     If they did a good enough hack job, I would get a correct harness for what you want to do with the truck (TBI or carb'd) and redo the engine bay.  But that is just me, I have spent my fair share of time fixing others screw up's over the years when it comes to wiring. 
     Now I don't waste my time anymore and just re-do it all instead of trying to splice and then go back several times to fix stuff here and there.

[Sean in NE]

Not very many junk yards around our area.
The biggest advantage I can think of of having EFI would be its ease of operation. My wife would drive the truck, and she isn't the greatest at starting a carbureted engine. For her its best if its turn the key and it fires up. No choke, or bumping the gas pedal during cranking. I think its easy, but thats just me.

I really don't know how much fuel efficiency there is to gain with EFI over carburetor. My 86 K30 has the 454 and the quadrajet and no matter loaded or not I get around 8mpg. At least with a carburetor I feel more comfortable to work on it then the TBI setup. I'm sure its easy to work on if a person has the right equipment. I guess I know the route I need to take. Also need to stop worrying so much about the electrical part. I've got a ways to go before digging into that. Need to finish gutting the 81 K30 and splice frames to the 89 3500. I'm going to go the ground up approach. I figured on hitting the open road when this project was completed. So I want to go thru everything and repair/replace what needs to be fixed so I don't get stranded alongside the road with a camper, boat, whatever. That or be at the mercy of a shop, and if they have the right part for the breakdown.

I feel so dumb when it comes to this project. I've done more on harder projects. Had an International pickup, and not alot of parts are available, or not much in the aftermarket world. Seems like this 89 GMC is so overwhelming since there is so much out there for these trucks. There is some more wiring and components than my IH I had(1975), but really shouldn't be too much different. I'm making this TBI thing harder than it really is, aren't I? LOL.

[DustyRusty]

Sean -

First, welcome to the site.  Where in NE are you from.  I grew up in the Panhande.  I have family there still and in eastern NE near Fremont and other areas.

Here is a link to the 1989 wiring diagrams.  The wiring diagrams, as well as the manuals, are available on this site.  All the manuals are found in the Tech Pages.   Wiring:  http://www.73-87chevytrucks.com/techinfo/7387CKMans//Wiring/ST_350_89_1989_GM_RV-P_Light_Trucks.pdf

I'll be watching your progress.  I like dually crews!

Rusty

[Sean in NE]

Sean -

First, welcome to the site.  Where in NE are you from.  I grew up in the Panhande.  I have family there still and in eastern NE near Fremont and other areas.

Here is a link to the 1989 wiring diagrams.  The wiring diagrams, as well as the manuals, are available on this site.  All the manuals are found in the Tech Pages.   Wiring:  http://www.73-87chevytrucks.com/techinfo/7387CKMans//Wiring/ST_350_89_1989_GM_RV-P_Light_Trucks.pdf

I'll be watching your progress.  I like dually crews!

Rusty

Rusty, we are over by Columbus, so Fremont is not far at all.

I haven't been on the forum in awhile, and thought I'd update everyone on the project. Basically I am going to get painless wiring harness to put in and start new. Plus most of the wiring harness plastic wrap is falling apart. Then thinking about doin efi from holley. Seems straight forward and I would love the ease of efi over carb. But I have a lot of other items to go thru yet before getting to the fuel delivery system. I need to start a topic on the progress of the crew cab but haven't got to it yet.