84 K5 build... converting to tbi

[EagleMark]

Knock sensor has to match ESC/Knock module that has to match cubic inch. There is only one for a 1988 5.7L Auto any truck.

From Rock Auto
ACDELCO Part # 213324 {#10456288}

There are three for that year. One for 4.3L, one for 5.0L and one for your 5.7L

[caliphatman8123]

hi all I'm currently working over the fuel lines for this swap... does anyone have diagrams to compare the 84 to the tbi fuel line set up?

[dyeager535]

Sorry no images. Lots of ways to make it work, but the hard part is from the TBI to the frame. If you pulled at least those lines from the '88, you can make something ork pretty easy. Hose is acceptable for short sections, especially at the low TBI pressure. But you need fuel injection hose.

[caliphatman8123]

Sorry no images. Lots of ways to make it work, but the hard part is from the TBI to the frame. If you pulled at least those lines from the '88, you can make something ork pretty easy. Hose is acceptable for short sections, especially at the low TBI pressure. But you need fuel injection hose.

I've robbed the two fuel lines I need from my donor burb... way to long so I have to shorten them... my issue is I don'y know which line goes where to the sending unit or to the tbi... this is where I need help

[EagleMark]

IIRC the bigger one to feed and the smaller one to return.

[caliphatman8123]

IIRC the bigger one to feed and the smaller one to return.

Tnak you now all I need is the other end at the tank... then I can shorten my lines and install them on the frame

[dave w]

I'm going to make a HUGE ASSUMPTION, that your not color blind (more than 10% of the male population have color blindness). I'm going to make another HUGE ASSUMPTION, you OWN and have the SKILLS to use a multimeter. If you DON'T OWN and DON'T have the SKILLS to use a multimeter, then STOP READING NOW!!!! For some unknown reason, vehicle owners who DON'T own a multimeter and DON'T have the SKILLS to use a multimeter are extremely PRONE to starting electrical fires, go figure!

Somewhere on the 88 wiring harness will be several wires that are pink with a black stripe (pnk / blk). The pnk / blk wire is powered from the ignition switch when the ignition switch is in the "ON" and "START" position. The 84 K5 Blazer has a PINK wire that goes to the HEI Distributor that is powered from the ignition switch when the ignition switch is in the "ON" and "START" position. The PINK wire from the 84 K5 will need to supply power to the TBI ignition coil PINK wire and supply power to the pnk / blk wires.

Somewhere on the 88 wiring harness will be several wires that are black with a white stripe ( blk / wht) which are Battery ( - ) Negative / Ground. If the 88 wiring harness is in excellent condition, there will be a couple large ring terminals (large enough for a 3/8" bolt to go through) that have blk / wht wires crimped to them. GM will often use a TAN wire for ground also, and usually the TAN wire will be crimped with a blk / wht wire on at the large ring terminal.

Orange (ORG) is used for Battery ( + ) Positive. Somewhere on the 88 wiring harness will be an ORG wire with a fusible link that was connected to Battery ( + ) Positive.

Somewhere on the 88 harness is a PURPLE wire with a WHITE stripe (PPL / WHT) that was connected to the starter solenoid "S" terminal.

That's it, four wire connections. Battery ( + ) Positive, Battery ( - ) Negative / Ground, Ignition Switch Power in both "ON" and "START" positions, and the Starter Solenoid "S" terminal.

dave w

[EagleMark]

Tnak you now all I need is the other end at the tank... then I can shorten my lines and install them on the frame

They should only go on tank sending unit one way. One is smaller 5/16th line the fuel return and one is larger 3/8th line. 3/8th line is the fuel feed. Take unit out of tank and it's easy to see return and feed from pump.

[EagleMark]

To add some color info to Dave w. post.

Orange is the same as red, 12 volt power always, key on or off.

Pink is 12 volt power key on.

Grounds can be black, black white stripe, Grey, Tan.

[dave w]

To add some color info to Dave w. post.

Orange is the same as red, 12 volt power always, key on or off.

Pink is 12 volt power key on.

Grounds can be black, black white stripe, Grey, Tan.

Good point, I've been thinking grey was a reference ground from the ECM. I haven't had need to ground the grey wires, because they have grounds from the ECM?

Anyway here is a video of me bench testing a harness, this one is a TPI. The Noid light shows the injectors are getting power (first on bank 2 then I transfer the Noid light to Bank 1) , the other light in the video is for Fuel Pump Power. The drill is used to spin the distributor to generate a reference pulse so the computer will "WORK".

dave w

[EagleMark]

For some reason there are differant colors in differant years. If you strip down a harness for stand alone wiring you can see junctions with all these ground colors.

I had one that fuel pump reference signal was grey?

[dave w]

For some reason there are differant colors in differant years. If you strip down a harness for stand alone wiring you can see junctions with all these ground colors.

I had one that fuel pump reference signal was grey?

I've also seen different colors for different years. I'm thinking its ALWAYS best to have the wiring diagram from the TBI donor vehicle, just to make sure the wire colors match the harness. I'm thinking its an excellent idea to bench test the harness just like, or similar to the method I showed in the video. I'm thinking its WAAAAAAAAAAY easier to fix, or figure out a wire harness problem on the bench rather that in a vehicle!

dave w

[EagleMark]

Pin to Pin is always perfect when colors don't match! Digatal Volt Ohm Meter is your freind.

I agree on building the harness on bench. Since I've been doing this I've never had an issue when installed or started. But since he is doing a retrofit I'm not sure this would work? He's using part of trucks CCC system to start and combining with EFI TBI system.

[caliphatman8123]

I still have the donor truck if it would be easier to rob the fuse block out of it and wire it in... would really like it to look like it came from the factory that way... lol

[EagleMark]

That would be my first choice. Just don't know the complications. Would be cleaner in the end even with more work!