[DimeTimeBlazin]

Recently picked up an '85 4x4 s10 with a carburetor 2.8L and I was wanting to swap the carb with a TBI from an '87 4x4 Blazer with a 2.8L. Trying to see exactly what all that is going to require me to do, before I start snatching parts off of them. I am assuming that I am going to need to swap out the computer since the 85 likely doesn't have the ability to hook up to and/or control the TBI. And aside from that, I'm guessing the vacuum system is still basically the exact same as far as number of vacuum lines and where they are going to go, but if not what kind of differences are we talking about? Thanks in advance for any help.

 

[jimmykicker]

Hey there. I did this myself. Look at the top of this section. There’s a sticky where I did it.

Your truck must be a California truck. Federal 82-85 trucks don’t have any computer controls. Short answer on that? Rip the entire wiring harness for the ECM (not the truck itself) and the ECM out of your truck. Swap the intake. You may be lucky and be able to make your ECM connections with your existing truck main harness. Not sure on that. But the existing ECM should have similar connections I’d think. Look for a schematic for both trucks on deathpheonix99 ‘s signature and compare. Good luck.

 

[jimmykicker]

Hey there. I did this myself. Look at the top of this section. There’s a sticky where I did it.

Your truck must be a California truck. Federal 82-85 trucks don’t have any computer controls. Short answer on that? Rip the entire wiring harness for the ECM (not the truck itself) and the ECM out of your truck. Swap the intake. You may be lucky and be able to make your ECM connections with your existing truck main harness. Not sure on that. But the existing ECM should have similar connections I’d think. Look for a schematic for both trucks on deathpheonix99 ‘s signature and compare. Good luck.

Here is the link to that post:

Converting to EFI. Finally...A little help

Are any of you guys on gearhead-EFI? I've been trying to join and idk what's up but I'm not awesome with computers and im getting aggravated. Any help would be greatly appreciated, thanks in advance. :)

www.s10forum.com

 

[DimeTimeBlazin]

Here is the link to that post:

Converting to EFI. Finally...A little help

Are any of you guys on gearhead-EFI? I've been trying to join and idk what's up but I'm not awesome with computers and im getting aggravated. Any help would be greatly appreciated, thanks in advance. :)

www.s10forum.com

It has computer controls but I was thinking since it is a carb truck from the years before they started using TBI, that it's probably not going to have the ability to hook up to and control the TBI. As far as the wiring, and functionality of the ecm. I'm slowly figuring out the vac line situation. Which is a complete mess and I'm pretty sure 80% are just not there, and the 20% that are, are rotted the extent that they may as well not be there.

 

[manbearpig]

If you're going through all of that, grab a 3.4l out of a Camaro with harness and computer and get yourself into the more modern world of fuel injection.

 

[DimeTimeBlazin]

If you're going through all of that, grab a 3.4l out of a Camaro with harness and computer and get yourself into the more modern world of fuel injection.

Well, I have the carb 2.8 L that is in the 85 and 2 running TBI 2.8L, one in a parts donor 4x4 blazer and one in a running and driving 2x4 blazer. So I may one day get a 3.4 motor but for today, I just need to make the truck run and drive better than it currently does. Most of its problems are vacuum issues. I was just looking into TBI swap because they are better than the carbs in my limited experience, definitely for cold starts. If it's gonna be a whole crazy amount of work I can live with the carb until the whole motor caps out and then I'll rip it out and replace the wiring harness when I put one of the TBI motors in. The amount of difference in in vacuum systems is kind of ridiculous from what I've noticed so far. So many extra and seemingly unnecessary things on the 85 that aren't on the 86 or the 87 TBI motors.

 

[jimmykicker]

You have everything you need for the swap. Now that I think about it, the existing wiring harness probably has at least the power run (and maybe the optical sensor) for the new ECM. But like I said, toss all of that. Pop the pins you need out of the existing truck harness. Put the ECM harness from the donor truck in there, connect power pins you removed that you need. You should be able to pop those pins out and into the new harness as if it came that way.. Forget that carb computer. Use the one from the parts truck. It's already set to run that motor. An yep, you can forget all of those stupid vacuum hoses. Run only what you need. The EFI systems use very few compared to the carb stuff. I despised all that junk on my truck too. Oh, don't worry about the optical sensor either. If your 85 has cruise, it's already there, and you can use it. If not, grab it off the parts truck. It will fit the old speedo head. Watch out for that tiny azz screw though. It is stupidly easy to drop, and you will NEVER find it. Your truck being CA emissions, it already has a CEL in the dash. My truck did not have one, but it had a place in the dash for it. I simply put a wire pin in that hole, ran it to the ECM and bam. There ya go. Course, you will need to run a fuel pump. I'd get a new one. It'll fit the old tank. However, there is one caveat here. The old tank senders are what they call "straight" tanks, and the electric pump tank senders are "cross over" tanks. You'll see what I mean. The fuel delivery line is the same, but the return and vent lines are reversed. Make sure that you connect the correct lines. I can't remember exactly if it's plug and play on that or not. Ignore that at your peril. You'll be pushing return fuel back into the vent, (blocking it) and possibly forcing fuel into the charcoal cannister. You will also need to mount your ALDL connector to interface with the computer. Don't worry. It's attached to the ECM already.

Don't worry. This isn't as hard as it seems. Just take your time. I didn't have a parts truck, so I had to run my EFI as a standalone harness which was more complicated than what you have to do. But removing the dash and trying to replace the harness to the fusebox isn't necessary at all. You will see in my thread where I had difficulty getting the truck started initially and my frustration.. This was due to me missing something basic. Had nothing to do with the install itself.

Since you have a parts vehicle, while you're at it, swap the belt systems too. Trust me you will be MUCH happier. Especially when you have to work on it. One belt. Buy a new idler pulley though. Ask me how I know! Almost burnt my truck to the ground. Confucious say, "Do not trust 30 year old bearing to not fly apart."

 

[DimeTimeBlazin]

That is what I was hoping it would end up being since it was an 85 and not one of the earlier years that had none of electronic stuff. 85 was the year where it was at least largely similar stuff, just without a throttle body system. I've finally gotten the vacuum system about 80% figured out for just getting the truck as right as possible for today, so I can really see how everything is running. It was pretty rough when I bought it, I'm assuming because of the vacuum system. I don't see how any of it was doing anything it was meant to. Every line was rotten and none of them were even plugged up to create pressure. So the fact that the guy was driving the thing daily is mind boggling the more I have worked on it. Lol.

 

[jimmykicker]

That is what I was hoping it would end up being since it was an 85 and not one of the earlier years that had none of electronic stuff. 85 was the year where it was at least largely similar stuff, just without a throttle body system. I've finally gotten the vacuum system about 80% figured out for just getting the truck as right as possible for today, so I can really see how everything is running. It was pretty rough when I bought it, I'm assuming because of the vacuum system. I don't see how any of it was doing anything it was meant to. Every line was rotten and none of them were even plugged up to create pressure. So the fact that the guy was driving the thing daily is mind boggling the more I have worked on it. Lol.

I will also mention that you can toss most of that stuff in the trash right now. All you need is vac advance, the vac cannister, power brakes, and line that controls the vents in the dash. Keep the check ball so it doesn't start blowing out the windshield vents when you accelerate. That's all I can think of.

Now, I did forget, you need the distributor from the other truck too. But you seem to have one. The used one I obtained was garbage, so I got a new one from Rock Auto. Works well.

 

[DimeTimeBlazin]

I will also mention that you can toss most of that stuff in the trash right now. All you need is vac advance, the vac cannister, power brakes, and line that controls the vents in the dash. Keep the check ball so it doesn't start blowing out the windshield vents when you accelerate. That's all I can think of.

Now, I did forget, you need the distributor from the other truck too. But you seem to have one. The used one I obtained was garbage, so I got a new one from Rock Auto. Works well.

Yep, figured out the dash vent situation earlier today while I was in the process of removing the stuff that isn't needed and trying to figure out where the dash vent line is supposed to connect to, because it was just hanging out with the line that goes to the cannister and another line that I haven't identified yet. I'm assuming that all 3 are running down to the T-case because they all go down behind the motor together right beside the trans dip stick. One was hooked to the cannister that is behind the passenger headlight. One was just laying beside that one, and the 3rd split off into the dash vent line and then had about 16"-18" of vacuum line and had a little plastic check valve that has the 1 end that was in the vacc line and then the other end is split for two lines to connect to. But that was it. Wasn't connected to anything. And the diagram doesn't show anything about those 3 lines. The 1, I'm assuming is meant to be going to the cannister, but the other 2 are a guessing game right now. I just have them plugged for the moment until I know what they are and where they are meant to go.

 

[DimeTimeBlazin]

On a positive note, I did manage to delete all of the useless check valves and nonsense that it started out with, and got the rotten lines replaced that were actually useful, and now it cranks a good deal easier and actually will idle now without having to feather the throttle to keep it from sputtering out. So that's an improvement.

 

[jimmykicker]

Understand. The 2SE to me is the worst carburetor I've ever dealt with. Anything is an improvement. It's surprising to me how peppy a 2.8 is if allowed to breathe. When I had the Edelbrock/Holley 390 combo, it was like a different truck. The first time I stepped on it leaving the yard for a test drive, I stepped on it like I normally did to get it moving. The tires spun! I was like....what the fork is going on here?? That thing couldn't spin a tire before in a mudhole full of oil, with the front brakes locked. After tuning it with the correct spring for the secondaries, I still got about the same mileage as I did with the Rochester. Much better throttle. If the 2.8 had an appropriate camshaft, my opinion is that it could make really decent power. The stock cam just doesn't allow it to its full potential. Swapping it to EFI was the best decision I made though. Starts easier and gets better mileage and power (with the mods).

 

[DimeTimeBlazin]

Understand. The 2SE to me is the worst carburetor I've ever dealt with. Anything is an improvement. It's surprising to me how peppy a 2.8 is if allowed to breathe. When I had the Edelbrock/Holley 390 combo, it was like a different truck. The first time I stepped on it leaving the yard for a test drive, I stepped on it like I normally did to get it moving. The tires spun! I was like....what the fork is going on here?? That thing couldn't spin a tire before in a mudhole full of oil, with the front brakes locked. After tuning it with the correct spring for the secondaries, I still got about the same mileage as I did with the Rochester. Much better throttle. If the 2.8 had an appropriate camshaft, my opinion is that it could make really decent power. The stock cam just doesn't allow it to its full potential. Swapping it to EFI was the best decision I made though. Starts easier and gets better mileage and power (with the mods).

Yea man, just the difference in my 86 blazer with TBI and the 85 pickup with a carb is so noticeable. The 86 I have to worry about trying to take off too hard on the throttle. The biggest worry with the 85 is it deciding to actually respond to the throttle as much as I'm giving it. It goes fine once it's going, but the getting going part is either lazy or it starts out acting like it's gonna do something and then gets lazy because you let off a little thinking it might actually do something. Lol. I fully agree about the 2.8 motors. I think they have a lot more potential than they are given credit for because of how they were built. And they seem to be very durable little motors.

 

[DimeTimeBlazin]

Understand. The 2SE to me is the worst carburetor I've ever dealt with. Anything is an improvement. It's surprising to me how peppy a 2.8 is if allowed to breathe. When I had the Edelbrock/Holley oil, with the front brakes locked. After tuning it with the correct spring for the secondaries, I still got about the same mileage as I did with the Rochester. Much better throttle. If the 2.8 had an appropriate camshaft, my opinion is that it could make The stock cam just doesn't allow it to its full potential. Swapping it to EFI was the best decision I made though. Starts easier and gets better mileage and power (with the mods).

Yea man, just the difference in my 86 blazer with TBI and the 85 pickup with a carb is so noticeable. The 86 I have to worry about trying to take off too hard on the throttle. The biggest worry with the 85 is it deciding to actually respond to the throttle as much as I'm giving it. It goes fine once it's going, but the getting going part is either lazy or it starts out acting like it's gonna do something and then gets lazy because you let off a little thinking it might actually do something. Lol. I fully agree about the 2.8 motors. I think they have a lot more potential than they are given credit for because of how they were built. And they seem to be very durable little motors.

Understand. The 2SE to me is the worst carburetor I've ever dealt with. Anything is an improvement. It's surprising to me how peppy a 2.8 is if allowed to breathe. When I had the Edelbrock/Holley 390 combo, it was like a different truck. The first time I stepped on it leaving the yard for a test drive, I stepped on it like I normally did to get it moving. The tires spun! I was like....what the fork is going on here?? That thing couldn't spin a tire before in a mudhole full of oil, with the front brakes locked. After tuning it with the correct spring for the secondaries, I still got about the same mileage as I did with the Rochester. Much better throttle. If the 2.8 had an appropriate camshaft, my opinion is that it could make really decent power. The stock cam just doesn't allow it to its full potential. Swapping it to EFI was the best decision I made though. Starts easier and gets better mileage and power (with the mods).

You wouldn't happen to know where the 3 vac lines that come up by the Trans dip stick at the back of the motor are meant to go would you? All I can find are the emissions lines diagrams and they don't have anything about those lines. I haven't crawled under it to confirm it, but I'm just assuming they go to the transfer case or transmission on the bottom side. But I have no idea where 2 of them go on the top side, and the only reason I think I know where one goes is because it was already hooked up to the canister behind the passenger side headlight. There is another one that is just as long as that one that was just laying there beside the one going to the canister, unplugged and not hooked to anything and then 3rd just came up to where the dip stick is and wasn't hooked into anything either and there isn't anything around there that I can find that it should go to. The 3rd did have a little plastic check valve stuck in the hose but that was it. I just removed the check valve and plugged the hose and then plugged the other hose. Not sure if that was the right move and just trying to make sure I'm not doing something very stupid that I won't realize was very stupid until it shows up in a big way later on. Haha. Thanks for all the help so far. I'm currently working through the wiring harness and getting everything ready for the TBI and ECM swap and getting all of the bells and whistles fixed because the previous owner apparently tried setting it on fire with the interior overhead light. Had both wires taped together. That was a first for me. I thought everyone knew that you weren't supposed to connect the hot to the not. Haha.