What to rob from donor truck for TBI conversion?

[punchinghorse]

I have a 1989 K1500 that is about to go to scrap. I want to swap TBI over to my '73 K5. I realize it's ideal if I have the donor truck sitting next to the K5 so I can have every possible part I'll need on hand, but the project is about 6 months to a year away, and the truck needs to be gone yesterday.

So...barring the obvious such as the throttle body and computer, what other wires, sensors, etc. should I grab? I would just swap over the entire engine, but I have no clue or confidence in its running condition.

 

[blazinzuk]

Every wiring peice you can get your hands on plus all sensors the more the better.

 

[dyeager535]

I'll second that. Every wire in that truck disconnects. Nothing needs cut, nothing. Strip every piece of the wiring harness complete. Stuff like the head/tail lights you won't need the wiring for, but if you want to convert over to better setups like tank mounted washer motor, cruise, etc., you would be best off taking all of it anyway. You'll need the fuse panel, so that means take dash apart and take all of that. Don't try to separate it, just take it. Trust me, everything has a disconnect or will come off in one piece.

Fuse panel unbolts, ECM plugs fit through the firewall where the wires go to the engine bay, everything on the motor disconnects, etc.

Probably won't use that intake, but either take the intake or remove and take all the brackets, bolts ,and sensors on it. Take manifolds, etc. It is a LOT easier to remove the engine/trans/t-case to get at that stuff. I did this fairly recently, with front sheet metal and the engine/trans/t-case out unbolting the various clips and clamps is a whole lot easier.

Take the tank, and all the fuel lines. Be careful disconnecting the lines. If they don't come loose at one connector (like the one from engine to frame) unbolt them at the fuel filter. Take the EVAP cannister. I don't believe the fuel fill neck/hose will work on the '73 since it doesn't use a fill door, but make sure the '73 fill neck/hose mates up to the '89 tank. Those big fill hoses are expensive to replace, IF you can get them.

Trying to shortcut removing parts now will cost you a fair headache later on, so take your time and do it right. Disassemble everything with care, and realize anything you break will cost you more later and just be a stumbling block at that time.

 

[punchinghorse]

Thanks guys. I will definitely take my time and not cut anything.

Regarding the tank...there isn't one :\ We bought it as a parts truck and the reason it didn't run was there was a problem with the tank and PO took it out and has no recollection of where it went. I had planned to just install an inline fuel pump and use the '73 tank. I know it doesn't have the baffles. How much of a problem will that be? I had an '87 that had broken baffles and it only created a stalling issue below 1/4 tank. Rarely will I take this truck offroad. There may be a spare TBI-era fill hose in my parts pile but I am not confident.

 

[dyeager535]

Personally I won't run anything but an in-tank pump if I have that option. Getting a used '87-91 tank/sender is still possible, but you'd want to remove the sender before purchase to ensure the baffles are still in place and the rubber hose on the sender/pump isn't split.

I'd go so far as buying the proper tank/sender before using an external pump, but some people have no problems with them. As I recall, externals are supposed to be mounted as low as possible, and that means cutting/splicing the factory lines, which I also don't like doing.

 

[punchinghorse]

Hello again...sorry to disappear for so long and then pop back up with another question. Have had extremely limited time lately. I have managed to pull nearly all the wiring, and I appreciate all the input received in this post.

What I'm wondering now is, do I need to keep the steering column? I have removed it and unplugged all of the connectors and not cut anything. Will I need this column for all of the ECM and TBI stuff to work? The column in my truck now is out of a mid-80s carbed truck. I'm not opposed to swapping columns again if it's necessary or preferred. However, if it's not, I'm going to sell this column as I have several people interested.

Thanks again!

 

[dyeager535]

I don't believe there is any difference TBI/non-TBI columns. Only differences are the years (wipers/hhigh beams on column, door chime/key in ignition, etc).

Never hurts to have a spare column though. lol

 

[paratrooper307]

Thanks guys. I will definitely take my time and not cut anything.

Regarding the tank...there isn't one :\ We bought it as a parts truck and the reason it didn't run was there was a problem with the tank and PO took it out and has no recollection of where it went. I had planned to just install an inline fuel pump and use the '73 tank. I know it doesn't have the baffles. How much of a problem will that be? I had an '87 that had broken baffles and it only created a stalling issue below 1/4 tank. Rarely will I take this truck offroad. There may be a spare TBI-era fill hose in my parts pile but I am not confident.

An inline pump will work fine, just buy a high-quality one and use rubber mounting to help isolate it from the frame to prevent noise. Also try to install it where the frame provides some protection, and no higher than mid-level of the tank, since inline pumps are designed to push as opposed to pull. An in-tank stock setup is ideal, but many vehicles run an inline pump with no problems. On the upside, the install is a whole lot easier.

Having recently completed a TBI conversion, the steering column is immaterial. My 85 has a steering column from an 87 and everything plugs up the same. You'll typically tap into the fuse box for switched power anyway. On mine there was an unused ignition shunt that was useful for obtaining "on" power that stays on while the ignition was cranking. I quickly found out that the choke circuit did not, lol.

 

[AZ79K5Project]

I recently completed my conversion on a 79. I went with a new baffled tank from Amazon for about $100 and an internal pump for ease rather than trying to adapt my non baffled tank with a return line.

It was a pain because I had a couple of gremlins I was chasing. After it was done, glad I did it.

 

[dremu]

For future reference, since you're prolly done by now: the brackets for the sensors and coil and such are very handy. Basically all the stuff that sits on top of the manifold, distributor included.

-- A

 

[4X4HIGH]

Arron, the TBI engine versus the early engines had a different angle on the four center intake bolts so it's not a "plug n play" situation.

Swapping the TBI tank into the 73 is a direct swap and then no issues with fuel pump stuff other than you would still need to run a return line along the frame rail.

 

[dremu]

Arron, the TBI engine versus the early engines had a different angle on the four center intake bolts so it's not a "plug n play" situation.

Swapping the TBI tank into the 73 is a direct swap and then no issues with fuel pump stuff other than you would still need to run a return line along the frame rail.

Fark. Guess it's good I stayed with the adapter then, or else I'd have Might-As-Well'd myself into an engine swap if I wasn't careful Edited original post to include only actual information I know from direct experience.

This means you gotta source an adapter plate for the throttle body as its bolt pattern is different than a carb. This means you may run into clearance issues with the air cleaner hitting the dizzy.

And oh yeah, you either gotta run the TBI sender/pump unit or use an inline pump and get a later sender with the extra fitting for a return line. The TBI pumps seem to fail at inconvenient times, so some guys cut an access in the floor above the tank. Means you don't have to drop the tank when the pump goes

-- A

 

[dyeager535]

Do any brackets mount to the center ones? IIRC the coil (and EGR solenoid?) bolts to two rear ones, what else is there?

On that same note, the two center bolts are spaced the same IIRC (because you can adapt the intakes back and forth, Vortec excluded) would that mean that any brackets could simply be bent to compensate for the angle?

 

[dremu]

Do any brackets mount to the center ones? IIRC the coil (and EGR solenoid?) bolts to two rear ones, what else is there?

On that same note, the two center bolts are spaced the same IIRC (because you can adapt the intakes back and forth, Vortec excluded) would that mean that any brackets could simply be bent to compensate for the angle?

Well, I just put TBI onto my ca-1975 hot air choke intake. YMMV for other years.

While the throttle/detent cable bracket mounted up fine, the center bolt for the coil was a bit closer so I had to notch the bracket a bit.

The ESC module and MAP sensor go onto a flat bracket on the passenger side, which didn't fit my intake. I chopped off one leg and did some clearancing and bending.

I didn't do EGR (no smog, yay) so I don't know what would have been involved there.

-- A