Lookin for help with 2.8 to 4.3 swap

Ok I don't post here much but I thought I'd see if someone has a different answer. I've swapped out my 2.8 drivetrain to a 4.3 drivetrain. I took everything for the wiring harness on the motor and even the dash since it is all electronic and mnie wasn't. Everything is from a 89 s10 pickup and my blazer is a 88 model blazer. I can get power to my pump and my injectors. But I can't get my injectors to work. It won't start. I'm hoping someone can help me. Maybe I should just go to a astro van carb setup but not really having the money to spend on it. Well thanks in advance.

I will ASS U ME that you used the 4.3 PCM.The inj has constant power and the pcm gounds the inj.So with that said,pin out the inj gound from the pcm while cranking and make sure the pcm is doing it's job.I will also ASS U ME that you check wiring diags to make sure that the pcm power in is corect and the grounds are correct.

I will ASS U ME that you used the 4.3 PCM.The inj has constant power and the pcm gounds the inj.So with that said,pin out the inj gound from the pcm while cranking and make sure the pcm is doing it's job.I will also ASS U ME that you check wiring diags to make sure that the pcm power in is corect and the grounds are correct.

I wish I knew what you were talking about. But I don't. I was told that if I swapped everything over it should run. But that wasn't the case. I did use the ecm from the donor truck. I have never done this before and if I had the money I would have just done a v8 but didn't have it. So if ya don't mind can you give me more details so i can understand what you are talking about. Thanks for any help.

First thing first.The pcm might not be wired the same.You did not give details on the years of your truck or the parts truck.For a short story lets sat that on your 2.8 truck that pin#c18 is power input, that might not be the same on the parts truck.Let's not get that far just yet.One of the most commen things to go south is the oil pressure sending unit.If it is bad or wrong the injectors wont fire.Gimme some details and I will help.The old,I pulled a 2.8 and dummped in a 4.3 now it wont start deal don't cut it.It is not all that bad if you have the knowledge and the reading material.Fill us in and you'll get it fired up.

First thing first.The pcm might not be wired the same.You did not give details on the years of your truck or the parts truck.For a short story lets sat that on your 2.8 truck that pin#c18 is power input, that might not be the same on the parts truck.Let's not get that far just yet.One of the most commen things to go south is the oil pressure sending unit.If it is bad or wrong the injectors wont fire.Gimme some details and I will help.The old,I pulled a 2.8 and dummped in a 4.3 now it wont start deal don't cut it.It is not all that bad if you have the knowledge and the reading material.Fill us in and you'll get it fired up.

Well That's what I did. But i used everything. I used the dash, the fuse box all of the dash wiring, the gauge cluster. I bolted everything in. I had to make the fuel pump wires longer cause they go only about half way back on the pickup and the go further back on my blazer. The only wires I didn't use were the ones for the stereo. I'm gonna run new wires for everything. The pickup has less wires then the blazer does but I'm not sure what the couple of extra ones are that go under the carpet. I tested the wires at my injectors and I can get power to them but that's all. I still have to bolt the dash down but I don't know if that is it. I didn't bolt it down yet so I can make sure it is all working. I had been told the cluster would have to be use also is why the dash got changed. I had to use it cause the electronic speedo won't work worth out it. Maybe if you van ask me some direct Q's I can tell you more. Does this help any?

Lets assume that this is the pcm wiring from the 2.8



PCM--> |--|--|-----|---|
+ + -

Now lets do the 4.3
|--|--|-----|---|
+ - +

The ( | ) are pins( wires) comming out of the pcm.As you can see they are in the same spot but not wired the same.They might even be the same colour.Give me the " your truck" year and details and give me the " parts truck" year and details and will look up the wiring diags.

Lets assume that this is the pcm wiring from the 2.8



PCM--> |--|--|-----|---|
+ + -

Now lets do the 4.3
|--|--|-----|---|
+ - +

The ( | ) are pins( wires) comming out of the pcm.As you can see they are in the same spot but not wired the same.They might even be the same colour.Give me the " your truck" year and details and give me the " parts truck" year and details and will look up the wiring diags.

Ok the donor truck is a 89 s10 pickup with a 4.3 motor and trans.
My truck is a 1988 s10 blazer with a 2.8 motor and trans that has been swapped out. But the 2.8 wiring is gone completely. It has all been changed over to the 4.3 wiring. Everything is all from the 4.3 but a few wires are not hooked up cause they are for the rear speakers. So the wiring has been completly changed with the donor wiring harness inside and out.

I guess no one has any ideas? I'm open to all of it but the wiring on my blazer is all from the donor truck. so the 2.8 wiring is not in my truck except for the inside lights the back hatch and the rear light. Oh and the pwoer stuff like locks, windows, and they all work. So if anyone has an idea please share it.

I’m not that familiar with the 88 & 89’s, but check that all the ground wires are hooked up. If you still have the donor truck go back and look for any ground wires or other wires you may have missed, especially wires running off the battery cables.

At this point I think you need to do trouble shooting for an 89 that won’t start. You can do a search on this board for such, but the main thing is; what is the fuel pump pressure reading, and do you have spark at each and every spark plug??

Do you know if the engine from the donor truck would run before you pulled it?

You might want to edit your Thread Title to read: - 89 Blazer No Start - as it will get more attention.

Report back and let us know what you find.

I’m not that familiar with the 88 & 89’s, but check that all the ground wires are hooked up. If you still have the donor truck go back and look for any ground wires or other wires you may have missed, especially wires running off the battery cables.

At this point I think you need to do trouble shooting for an 89 that won’t start. You can do a search on this board for such, but the main thing is; what is the fuel pump pressure reading, and do you have spark at each and every spark plug??

Do you know if the engine from the donor truck would run before you pulled it?

You might want to edit your Thread Title to read: - 89 Blazer No Start - as it will get more attention.

Report back and let us know what you find.

Hey thanks for the tips. I would delete this if I could but I can't. I've decided to go carbed and I found all of my parts to do it. I have too much going on right now and I don't have the time to get the tbi going. I've checked and triple checked. So I'm gonna go with a carb setup that I just found and made arrangements to buy next month. I'm not loaded but i have to get it running and so far it's taking to long to get the tbi going. But just wandering. If the injectors aren't giving any gas then what would the fuel pressure have to do with it? I'm just curios about that part.

. . . If the injectors aren't giving any gas then what would the fuel pressure have to do with it? I'm just curios about that part.
You have to have x amount of fuel pressure before the injectors will fire. I don't know the exact psi for an 89, but it's probably somewhere around 55-60 psi. Your 88 fuel pump may not be putting out enough psi to trip the 89 injectors.

Course, if you don't have any spark to the plugs a carburetor systems won't do much for ya.

You have to have x amount of fuel pressure before the injectors will fire. I don't know the exact psi for an 89, but it's probably somewhere around 55-60 psi. Your 88 fuel pump may not be putting out enough psi to trip the 89 injectors.

Course, if you don't have any spark to the plugs a carburetor systems won't do much for ya.

Ok that makes sense. But I do have spark to the plugs and the distributer I'm getting will already be setup for the swap. Now the thing about the pump is the pumps between the 88 and 89 are supposed to be the same. But I need to find out more. You can get me on aim if you have it. Mine is layitlo88. Thanks for the info.

Ok I just checked autozone where I bought the pump in my truck and it says that the parts numbers are the same and they both put out 9 to 13 psi while the engine is running or not. But everything I'm getting for the carb setup will be everything I need to swap to the carb. I'm not sure on the pump but I will need the carb to get the info to see what pump I need. But I can get a universal one for about 50 so it should run afterwards. The truck that has the parts runs now and had the carb built not long ago. So it should run.