'87 TBI 350 into '85 swap

[FightinTXag]

I bought an '87 2wd Burb with a strong running TBI 350 with about 10k mi since rebuild for $1800. My plan is to take the recently rebuilt 350 along with all of the TBI and swap it all into my '85 K10. If I can get a couple hundred for the motorless beast when I'm through, I'll have a recently rebuilt TBI 350 for not much more than a long block +core charge. Plus I'll have the convenience of taking my time with the donor sitting right next to my truck and the peace of mind knowing I've got everything I need and every piece is in good working order.

So I started by pulling my tired old 305 with the shot rear main seal, the bad valve guides/seals, and the Q-jet/ESC HEI combo that seemed to run differently everyday. I'll probably spend most of the rest of the week cleaning up my engine bay.

I think my plan of attack now is to then pull the motor from the Sub. As I disconnect everything I'm going to label it carefully. Then with the engines out of both trucks, I'm going to take my time transferring the wiring and plumbing the fuel lines. I figure it'll be easier to route everything if I can crawl in the engine bay without the motor being in the way.

I plan to go with an inline external pump unless I can get a good deal on a tank with sending unit & pump from a SWB '87 at Pick 'n Pull.

My '85 came with cruise so VSS should be there on the speedo same as the '87 Burb. Since both VSS are on the speedo, I shouldn't have any problem with pulse per minute discrepancy if I keep my cluster. Right?

I'm going to look at swapping out everything including the cluster (I'll have to put my clock on the Sub's panel if I go this route), but I'm not opposed to making a couple of splices if that is simpler than swapping out a bunch of in-cab wiring. Thoughts?

Anything else I should be considering? Is there any reason to wait until the motor is in place before tackling the wiring or fuel lines?

Also, is it ok to lift the TBI 350 using one of those carb plate hook things? I know the intake manifold is aluminum and I don't want to crack it or strip the screws on that thing.

 

[Russell]

Sounds like an excellent foundation for a swap!

I'd definitely move all of the wiring from the burb over to your 85. You'll be pleasantly surprised how easy it is to do, only requires you to pull the dash pad, instrument cluster and to drop the steering column down. The burb wiring harness should bolt straight in, and shouldn't have any differences less the extra fuses and such for the EFI, and maybe for the courtesy lighting. Since your truck had the ESC system, you should be able to pop the TBI ECM in directly where the old EST controller sat before.

The VSS from the 85 is identical to the VSS in the 87, and as long as the 85 cluster has a service engine soon light in it, you should be able to use it with the 87's wiring without making any modifications.

Fuel system shouldn't be half bad to pull off, just move the burb setup over as much as you can, then bend up some new line to fit, or get the full setup from an 87

Don't worry about lifting the engine by the intake, just make sure you use the longest bolts you can to get a bunch of thread engagement

 

[4X4HIGH]

You seem to have a good handle on it. The only thing is i would NOT use the carb plate pull hook on the TBI manifold since there are only 3 bolts that hold the TBI on. At any rate, IIRC the TBI engine has pull hooks in either corner just for this purpose.

 

[dyeager535]

Instrument panel connector is part of the wiring harness, so no worries there. Just swap the cluster at the same time. Otherwise you would want to swap the choke light filter for the check engine filter from the '87, and re-pin the cluster connector accordingly.

You MIGHT not be able to add the clock to the newer cluster, I know my '90-91 cluster is cast differently in that area, and I can't put a small fuel gauge in there because of it. I don't know how quickly they changed that, it would likely coincide with whenever they went to all digital display radios that had clocks.

As to fuel pump, if you can find the right donor (same truck) with the in-tank setup, grab the lines as well, that will save you a BUNCH of hassle and money.

 

[FightinTXag]

The only thing is i would NOT use the carb plate pull hook on the TBI manifold since there are only 3 bolts that hold the TBI on.

Hmm. Didn't know TBI only had 3 bolts. I might not have a pattern on my lift plate to match that.

At any rate, IIRC the TBI engine has pull hooks in either corner just for this purpose.

I tried to use the hooks on my 305 when I was pulling that, but the extra chain lenght meant I was 7-8" short of clearing the radiator support with the hoist all the way up. Sucks having to set the motor all the way back down and change attachment method.

Instrument panel connector is part of the wiring harness, so no worries there. Just swap the cluster at the same time. Otherwise you would want to swap the choke light filter for the check engine filter from the '87, and re-pin the cluster connector accordingly.

Sounds like the new harness won't have provisions for the 4x4 light then. I guess I can wire it up separately if I want to retain it.

As to fuel pump, if you can find the right donor (same truck) with the in-tank setup, grab the lines as well, that will save you a BUNCH of hassle and money.

Ok, I'll see if I can come up with that. Is there a good way to test the pump and sending unit before installation? I'd hate to have to drop the tank again because the one I got from the junkyard was trash. And they're too expensive to replace just for insurance.

 

[dyeager535]

New harness should be setup for 4WD light. My '90-91 cluster doesn't use a separate wiring harness like some earlier stuff, but unsure when they finally integrated that into the cluster connector. I would expect '87 they would have finally integrated them. In any case, swapping the filters and pins around for the cluster are easy, those pieces all fit the same.

I don't know about a "good" way to test them, but all you need it 12V to the pump and ground to run, so all you'd need is a battery with some wire to get it to pump. That doesn't tell you pressure nor that it will hold pressure though. Fuel gauge can be hooked directly up to the sender wire (using the studs on the back of it) and with 12V and ground, you can manipulate the float and watch what the gauge does. This is a bit unrealistic because the float likely will never reach full travel in either direction as installed, but it can show dead spots, etc.

 

[Russell]

I think his old cluster should have a SES light for the spark control module, and if it has a VSS on the speedometer, then it should be totally fine to use with the 87 harness. I dunno about the newer trucks, but in my 80, the 4x4 light wiring was seperate from the main harness like the courtesy light harness.

Testing the pump would be a matter of seeing if it makes any noise when you put 12 volts on it. If you can, it'd be a good idea to put a gauge and regulator onto the pump and make sure it puts out the proper pressure and volume. Testing the sending unit would involve checking the resistance, it should be 0 - 100 ohms if I recall correctly. As mentioned by dorian, check to make sure there are no dead spots in the potentiometer.

As far as lifting it goes, I lifted my TPI engine into my truck with two bolts out of the fuel rail bolt holes. I had no problems with them pulling out or what have you. That isn't to say it is totally safe, but in my case, it appeared to be the case.

 

[dyeager535]

I pulled the "CHOKE" filter out of my older cluster, took a filter with "CHECK ENGINE" and swapped them. Obviously it doesn't really matter, you just need to know where the check engine light bulb is, so you know when you've got a problem.

I've always been leery of bolts into the aluminum intakes, just because of how easy they strip in use, but I think I'm being way too cautious. What are they, 1/4" bolts or something for the TBI mounting?

The way I typically see it done is a bolt in a head on the backside of the motor, and a bolt in the frontside of the opposite head, holding the chain in place. With this method you probably don't want valve covers on it, I've dented them before. But it lets you get the boom right close to the engine.

Re-reading the initial post talking about labeling, in my experience the problem isn't going to come from not knowing what goes to what, because the connectors are all different, and only fit one way. The REAL problem is figuring out how GM routed the wiring so cleanly and away from potential problem areas like heat sources and sharp edges. I had a real problem with the thick wiring around the steering column, and the main one in the engine bay.

In my opinion my wiring looks terrible, but I am also using a car harness which is much longer in some spots, too short in others. If you have the donor, I'd pay more attention to how the wiring is routed and held in place than which connectors go to what. Detailed pictures of wiring junctions (where two looms meet) and then where the wire loom goes from there.

I'd also perhaps plan on stripping the wire loom off, and getting new, as well as taking a rag to the wires inside the loom with paint thinner. My wiring was in good shape, but the insulation was mostly coated with sticky goo (probably motor oil, road debris, etc) which made it hard to deal with, and the loom was also coated in grime, and/or falling apart.

Be careful when removing the wiring from the clip on wiring retainers, the ones that push through a hole in the sheetmetal and lock there. Those are reusable, and I've no idea if you can even buy good ones to replace them. In any case, take a bit of time to remove them intact.

 

[FightinTXag]

New harness should be setup for 4WD light. My '90-91 cluster doesn't use a separate wiring harness like some earlier stuff, but unsure when they finally integrated that into the cluster connector. I would expect '87 they would have finally integrated them.

So the new harness will have provisions for the 4WD light even though it's coming off a 2WD suburban? I (like you) assumed it would be incorporated that into the main harness, but I also figured there'd be 2WD and 4WD specific main harnesses. That'd be a lot of extra wire and connections in every 2WD Blazer, Sub, and Pickup out there and that stuff adds up when you're talking about millions of units.

I think his old cluster should have a SES light for the spark control module,

Mine actually has a CHOKE light, but like Dorian says swapping out the light filter will make it SES. With the current system, the only time I've ever seen the CHOKE lit is once when I let it get too low on oil and the oil pressure gauge began to read zero at idle.

The REAL problem is figuring out how GM routed the wiring so cleanly and away from potential problem areas like heat sources and sharp edges.

Thanks for the tip. Maybe I'll make a video that kind of follows all the wiring underhood so I can use that for reference when I'm doing the swap. Then do the same thing for under the dash.

 

[dyeager535]

Ahh, well, 2WD may be different, you are right. I guess it really depended on the bean counters, whether it was cost effective to buy 1 million of 2 harnesses, or two million of one harness. But having a diesel harness before, I noticed there were a fair number of extra connectors that similar year gas ones didn't have.

As I recall, the 4wd light is a simple loop/addition, one wire gets 12V ignition from the fuse panel (yay later fuse panels with all the accessory terminals) which goes to the switchthen routes back to the fuse panel. It may even be a ground, it would certainly simplify the wiring to have the bulb get 12V ignition all the time, and the switch just complete the circuit to ground. GM must have had a reason for running two wires the whole way though, I'm probably missing a fundamental wiring problem with that idea.

On wiring tracing, a video of the "before" would be helpful, and probably as you remove components to get at them as well, like if the starter wiring runs down the front of the block, how it looks once the alternator is removed.

 

[FightinTXag]

I got the 350 pulled from the sub today. I'll spend the weekend swapping over the wiring and plumbing the new fuel pump (I wasn't able to find a SWB 87 at any of the wrecking yards).

My mechanical fuel pump had 2 fuel lines running to it from the tank and then one running up to the carb. I guess the mechanical fuel pump has a return line for when the Q-jet's float bowl was full? Anyway they are two different sizes - 3/8 & 5/16 I think. Is the smaller line sufficient for the TBI return?

Also what should I be looking for in an aftermarket fuel pump? 9-15psi? What kind of GPM?

I'm going to hack off the Sub's fuel filter setup so I can always remember to just get a OE '87 Sub fuel filter when I need to replace it.

 

[Russell]

More volume is better than less. The regulator will return excess volume back to the tank through the return line. The lines for the carb pump are the correct diameter for the TBI supply and return.

 

[FightinTXag]

Ok, I've done some research and it seems most have good results with the Carter P5001. Going to pick one up at Napa tomorrow.

I got all the wiring pulled out of the sub. The only place I cut was the 4 wires for the rear lights the 2 wires for the fuel sender and pump. I'll splice those into my truck's existing harness and run a new wire for the new pump.

I was hoping the engine harness was a little more stand-alone than it turned out to be. I had to get all of the headlights/markers/etc from the radiator support, and of course I had to cut the wiring for the rear lights. I'll be swapping the cab harness too.

While pulling the engine harness out, the wire for the knock sensor broke, and I can't find where it went to splice it back in. Can someone give a thorough description of exactly where the knock sensor wire exits the underhood harness or even better, a picture showing some of the other branches for reference? I'll be forever in your debt.

 

[FightinTXag]

Ok, I found the broken wire in the harness for the knock sensor. I kept looking for it breaking out of the loom somewhere, but it was at the very end of the harness with the starter wires.

I got the underhood harness swapped over, and the cab harness pulled out of my pickup. Hopefully tomorrow I can get the cab harness from the Sub installed, deal with the fuel pump, and then drop the motor onto the mounts. Then I hope to have it running by the end of the day on Tues.

 

[FightinTXag]

I thought I had everything done, but I've got some problems.

For one thing, the headlights and parking lights, horn, instrument panel lights, dome light, SES light, and clock all aren't working. The brake lights, turn signals/hazards, and radio work fine. I used a multimeter, and I have zero resistance between the firewall junction block and ground. So I guess I've got a grounded out wire coming from the starter maybe?

Additionally, the fuel pump doesn't come on. I used a jumper to the test/prime lead of the fuel pump relay and that kicks it on fine. So I don't know if that's related to the short that's causing all my other problems or not.

Jumping to the fuel pump relay to get the pump running and trying to start the truck, it will not fire up. It turns over just fine. I pulled the coil wire and it looks like there's spark to the distributor at least. I watched the injectors and they are squirting gasoline, but it's kind of weak and not really regular or rhythmic like I'd expect. I know the ECM has an orange wire that is constant battery power from the fuse block. I'm hoping that my short is denying power to the ECM and causing the no-start condition, but I'd think that would mean I'd get no injector pulses at all if that was the problem.

 

[dyeager535]

I don't know about the resistance portion, but you will have continuity to ground unless you disconnect negative battery cable. For instance, your ECM is grounded, and it's got power all the time, thus the positive wire has continuity to ground. Probably made an electrical engineer cringe with that description, but I believe that is an accurate description.

Almost sounds like you've got a dead fusible link, did you check for 12V at the fuses in question, if any of them are actually fused? Tough one, off the top of my head I can't think of any place you should be checking for 12V that is easy to test and related directly to your problem that doesn't have multiple other possibilities. If you can easily reach it, I'd suggest pulling your headlight switch and check that at least one wire has 12V, since they are operable regardless of ignition position.

I'm not clear exactly how the fusible links are run on all the trucks, but usually GM has two, one controls lighting, the other the engine, so you can lose "half" of your electrical. If you've got fusible links between the junction block and firewall connector, check for 12V at the junction block, if you've got 12V there, pull the firewall connector and check for 12V on that end, while jiggling the wires.

Your check engine light bulb is grounded by the ECM, but 12V for the bulb comes from the fuse panel, so no voltage at fuse panel, no light.

 

[FightinTXag]

I don't know about the resistance portion, but you will have continuity to ground unless you disconnect negative battery cable. For instance, your ECM is grounded, and it's got power all the time, thus the positive wire has continuity to ground. Probably made an electrical engineer cringe with that description, but I believe that is an accurate description.

Aha! Yeah, I think you're right.

I got it figured out when I stumbled across this thread:
http://coloradok5.com/forums/showthread.php?t=202875&highlight=Check+Engine+Light
Guy had the same symptoms as me when he was swapping in a 383 (but he hadn't tried to start it yet).

the check engine light does not come on, Also no sound coming from the fuel pump... No power to the head lights, instrument panel or cabin light... Got blinkers front and back, wipers, brake lights... There must be a wire that I did't hook up, but I cant find it

Turned out he hadn't hooked up a wire that lead from his positive battery cable to the lug on the alternator. So I went to look at my battery cables. Apparently between 85 and 87 the path for battery power changed.

The 85 battery cable only lead to the starter. The 85 harness got all power from the starter.

The 87 battery cable leads to the starter AND the alternator. The 87 harness then got power for the junction block from the alternator lug. (Obviously other things like wipers and brake lights still took power from the starter location since they were working).

So the 87 harness was looking for battery power for the junction block from the alternator lug, but my 85 battery cable was only powering the starter. So I cut up the 87 battery cable to make a jumper to run from the positive battery post to the alternator lug and everything is working fine now. She fired right up!

I guess I should replace the jumper I made with a fusible link, or maybe just put an inline fuse really close the battery? Or is it maybe already a fusible link since it came out of the 87's battery cable? Or maybe not since it was the portion aft of a crimp connection. Thoughts?

 

[dyeager535]

Factory fusible links I've seen are always blatantly obvious, black plastic piece maybe 1.5" long, at least double the diameter of the wire itself.

Personally I think the inline fuses would be fine, although you shouldn't ever pop a fusible link. They are there "just in case", so whether or not it's worth it to add a fuse is up to you.

I'm glad I haven't had to deal with the alternator wiring issues (yet) but I do have the newer style stripped back from the engine harness, just tucked up behind my jack if I ever need to replace my alternator with some monstrous newer one.