Considering a TBI Swap

[MrGiggles]

The OPS that your currently using might work, depends on which switch type (gauge, or light) and the OPS connector (Male vs. Female plug).

Most all 1995 sensors are the same as the 1987 ~ 1990 sensors. Two sensors that I can think of that are different. One would be the Knock Sensor (100K vs. 4K resistance). Knock sensors for Manual and Automatic transmissions show different part numbers starting in 1991. Starting as early as 1991 the ESC module was moved inside the computer and incorporated with the Memcal. The 1995 TPS is round not flat.

dave w

If that's the case I will pull a knock sensor and ESC from an older model. My OPS was pulled from a 4.3. It was the same as the diesel (the original in the diesel was broken) and plugged right in. It is a black plastic cylinder with a 2 or 3 wire female plug on the end.

Alright, I give? What's an OPS?

O2 sensors wear out and are to cheap to pull used, same for CTS.

Don't expect miricles when you get the conversion done on a stock chip! But that cam will tune very nicely.

Oil Pressure Sender. I was just gonna grab the CTS and 02 because I could get them for a couple bucks. If they work, great. If not I'm not out much. It's also nice to have spares. I am hoping it won't take much to get my engine running good. It's more or less stock, except a little higher compression than stock.

[dave w]

On the older TBI systems, the OPS had two functions. The first functions was to provide a parallel path the fuel pump relay to supply power to the fuel pump, usually a two wire OPS. The second function on the OPS was to send a ground to the check oil light in the instrument panel (if the oil pressure dropped below 3 ~ 5 PSI) or provide a resistance for the oil pressure gauge in the instrument panel, usually a 3 wire OPS.

dave w

[MrGiggles]

The truck must use a 3 wire then because I have a gauge.

If the only thing the oil pressure sender does for the TBI is running the fuel pump, then I can leave it out right?

[dave w]

The truck must use a 3 wire then because I have a gauge.

If the only thing the oil pressure sender does for the TBI is running the fuel pump, then I can leave it out right?

To accurately answer your OPS question, I would need to review the wiring schematics you have, or plan to use. I have no idea how the OPS is currently wired.

A "Stand Alone" TBI wiring harness has the fuel pump relay power the fuel pump and does not use the OPS. The same can be done to a factory harness with careful planning.

dave w

[MrGiggles]

To accurately answer your OPS question, I would need to review the wiring schematics you have, or plan to use. I have no idea how the OPS is currently wired.

A "Stand Alone" TBI wiring harness has the fuel pump relay power the fuel pump and does not use the OPS. The same can be done to a factory harness with careful planning.

dave w

What I was planning is to leave my current OPS alone to run the gauge, and not use one in the stand alone harness for the TBI.

[dave w]

What I was planning is to leave my current OPS alone to run the gauge, and not use one in the stand alone harness for the TBI.

Good Plan.

The factory TBI harness supplies FULL BATTERY "+" power (usually orange color wire) to the OPS.

dave w

[MrGiggles]

I had a pretty successful morning. Had to run around and pick from several different vehicles. The 95 Suburban was not available anymore.

I got a distributor, coil, and MAP from a 93 Suburban.

I pulled a TB with injectors from a 91 Pickup.

I got an ESC and harness from an 88, and what I suspect to be a 1227747 ECM. The sticker is faded but the plugs are right and it was sitting in the seat of an 89. Is there any way to identify these without the sticker? The chip under the removable cover shows AKSB.

Best part was I got it all for 50 bucks. I still need a knock and 02 sensor.

[EagleMark]

AKSB is from a 1227747 but a V6 Auto. So it will have the wrong Netres/small chip in it for LHM.

[MrGiggles]

AKSB is from a 1227747 but a V6 Auto. So it will have the wrong Netres/small chip in it for LHM.

That's what I found out as well. The truck was a carbureted V8 conversion. Is it as simple as swapping the chips for a V8 M/T?

I'm having a little trouble figuring out my harness. Next to the two ECM plugs there is another white plug with 12 or so wires in it. I'm not exactly sure what it's for but from what I've seen the injector and and some other important wires go into it. Anybody know what that is? Is there a walkthrough or how-to that walks me through the harness fixing?

[EagleMark]

Track the wires one by one! That plug goes to dashboard CEL, IIRC the DRAC etc...

Yes you can swap in a V8 Netres. A V8 manual chip will help but there are always things that need turned off in conversions and a stock chip needs help anyways...

[MrGiggles]

Track the wires one by one! That plug goes to dashboard CEL, IIRC the DRAC etc...

Yes you can swap in a V8 Netres. A V8 manual chip will help but there are always things that need turned off in conversions and a stock chip needs help anyways...

I wish I could find a damn ECM out there. I have no idea why every single one is pulled. I hate to buy a V8 chip on ebay.

After 3 hours I finally got the harness figured out. Printed off a factory diagram for the truck and traced each one and removed what I didn't need. That clear plug housed most of the ALDL wires, the CEL light, and a couple others that were easy to figure out. I cut them around 8" from the ECM plug and labeled them so I know what they do. It's all narrowed down to the bare minimum and ready to go, but I have a couple of problems yet.

1. The TPS plug on my TB and harness don't match up. The TB has a small circular plug and my harness has a rectangular. I guess they changed them. I will have to get the right plugs at the salvage yard next time I go. I need some new plugs anyway.
2. I must be missing a couple of cables for the coil and distributor. From what I understood the coil has two plugs, one from the truck (it wasn't on my harness) and one that goes the the 2-pin plug on the distributor. I don't have either of those but do have the 4 wire plug for the distributor.

I still have to order an carb/tbi adapter and figure out a fuel pump also.

After some research it looks like I can use an inline Ford pump from the late 80's model pickups. They will make 40psi. However I have read that they aren't great at pulling fuel, so I may mount the diesel lift pump in place on the frame, install a filter after it, and then mount the Ford pump, then plumb it into the TBI.

[brian617]

After some research it looks like I can use an inline Ford pump from the late 80's model pickups. They will make 40psi. However I have read that they aren't great at pulling fuel, so I may mount the diesel lift pump in place on the frame, install a filter after it, and then mount the Ford pump, then plumb it into the TBI.

Thats what ford did basically, only using in tank pumps to supply fuel to the frame mounted pump. Also they used the in tank pumps for tank switching.

[MrGiggles]

That's good. Should work if I can find a pump.

The pressure regulator is inside the TBI unit right? Will stock pressure work for me?

[Nasty-Z]

Why don't you simply remove the Diesel sender from the fuel tank and replace with a sender for a truck with a gas engine ? Tank is the same for Diesel vs Gas . This is what I did on my '93 K3500 which was a 6.5 turdblow Diesel . I used the position on the frame rail for the fuel filter since the fittings were already there . Extend the F/P wiring from the frame to the tank and you are all set. Much simpler and it will perform much better in the long run .

Good to see you here , I assume that Flywheel you got from me is still in the truck ?

TOM

[MrGiggles]

Why don't you simply remove the Diesel sender from the fuel tank and replace with a sender for a truck with a gas engine ? Tank is the same for Diesel vs Gas . This is what I did on my '93 K3500 which was a 6.5 turdblow Diesel. I used the position on the frame rail for the fuel filter since the fittings were already there . Extend the F/P wiring from the frame to the tank and you are all set. Much simpler and it will perform much better in the long run .

Good to see you here , I assume that Flywheel you got from me is still in the truck ?

TOM

I had considered it but I didn't know that the tanks were the same. That and I don't really wanna drop the tank on mine, and since my parts are coming from a scrap yard that means I would have to drop the tank on the donor as well. Do you know if the sending unit is the same for the gauge?

Yep I am still running that flywheel. She still spins true.