Tbi swap build thread

[iceship]

Any of you guys put a. obd-11 in your truck. .. I'm taken engine and trans out my old 93 roadmaster wagon..
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[rfmaster]

Originally Posted by iceship

Any of you guys put a. obd-11 in your truck. .. I'm taken engine and trans out my old 93 roadmaster wagon..
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The engine and trany from 93 roadmaster should be equipped with TBI which is OBD-1. Last year for TBI in B-body before cast iron LT-1 was introduced in B-body in 94 model year. OBD-II vehicles were mandated by 1996 model year. Between 1993 and 96 GM had some car platforms that were equipped with hybrid OBD - the so called OBD 1.5

What is your question regarding TBI - OBD-1 (yes we run it in our trucks) ??

[iceship]

Obd-1 plug does it just run to the pcm or its it more to it than that. .
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[rfmaster]

Originally Posted by iceship

Obd-1 plug does it just run to the pcm or its it more to it than that. .
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1) PCM = power train controller found in late model OBD-1, 2 systems and is used to control EFI and transmission shifting (4L60E, 4L80E). Prior to 92 ECM only controlled EFI and TC lockup.

2) OBD-1 plug was wired to a number other modules - anti lock computer, Air pump solenoid. In early OBD-1 prior to 92 model year plug provided interface to ECM

[iceship]

The plug under the dash for tune and diagnostic scanning
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[rfmaster]

OBD-1 plugs are only used for scanning.

Tuning is done by reprogramming EPROM contents inside ECM. Most of GM OBD-1 ECM's used UV-EPROMs which required physical removal of the EPROM from the ECM for re-programming. Starting around 94 time frame some of the GM cars were equipped with FLASH memory which allows for reprogramming of EPROM calibration without removal. Roadmaster ECM is older style ECM (with removable EPROM) since 93 Buick was equipped with LO5 and 700R4.

[bizzybody]

I'm attempting to use a drivetrain from a 1991 1 ton in a 1982 1 ton, so no emissions controls on either. (The 91 had a single exhaust cat is all, absolutely none on the 82.)

It has a rebuilt 700-R4 with the speedo drive changed to mechanical plus an external VSS from Jags That Run.

The 91 ran great* but now that I have it all in the 82, I cannot get the injectors to open up and the fuel pump runs all the time the key is on.

If I pour gas down the throttle body it will run. The fuel pump is new, in tank OEM type. I got a 40 gallon rear mount tank from a 1987 or so Suburban with TBI.

What do I look for to correct these two issues so that the pump will run a bit then stop until the engine is cranked then running, and the injectors never opening?

It has plenty of fuel pressure, it's soaked through the gasket around the top of the injectors. Excess fuel will come out the return port on the throttle body so the regulator is doing its job.

I installed new injectors and pressure regulator diaphragm and spring (which was broken).

The engine has new crank (cast steel Eagle) King bearings, new rings, new spark plugs and wires, new billet small cap HEI distributor. All the stuff it needs to run, which it will if the injectors and pump would work when they're supposed to.

I've also upgraded the instrument cluster from the idiot light one to the one with oil and temp gauges. Got the wires moved to the right places on the connectors for that.

Until the bleeping thing will start and run properly, it's a stalled project.

*I don't know how it ran great with badly worn crank and bearings and nearly 1/4" slop in the distributor shaft, but it did - until it got warm then it'd just stop. I presume from a sudden oil pressure drop once the oil thinned. Not a problem now.

[brontotx]

The injectors not firing could be due to not getting a signal from the distributor. That is, the ECU won't fire the injectors unless the distributor sees that the engine is spinning since you don't want to dump fuel into a stationary engine. Check the plug on the distributor or check and/or replace the reluctor ring or pickup inside the distributor.

Another issue could be stuck injectors, but you said it ran fine in the '91. How long has it sat? If longer than 6 or 8 months, try lightly (or not so lightly wrapping on the injectors with a screwdriver handle (hit side of injector) to see if the are stuck and you can restore firing. Another option is to get a "noid" light that will flash when given a signal from the ECU - simply unplug one injector at a time, insert the noid light and see if it flashes. If the light flashes, you have stuck injectors otherwise, go back and look at the distributor signal and correct wiring. *EDIT: just saw that you bought new injectors and distributor - strange!

As for your fuel pump staying on all the time, you should have a fuel pump relay that provides power to the fuel pump when the relay gets 12V either from: (1) the ECU sending it a signal for ~5 seconds after detecting a signal from the ignition on circuit or (2) from a closed oil pressure switch. See diagram on Post #7 here.

In other words, the ECU fires the fuel pump initially during start-up and the oil pressure switch keeps it running after start-up. Note that the oil pressure switch is a safety feature since, if you were in an accident and the engine died with the ignition on and you were unable to turn the key off, you wouldn't want the fuel pump to keep pumping fuel. By the sounds of it, your oil pressure switch may be closed all the time - to check, just unplug to open the circuit. If that stops the fuel pump from running continously, then you can confirm a closed oil pressure switch with a OVM. Other than that, double check all the wiring.

Good luck and hope this helps.

[bizzybody]

I forgot to mention that it does get power to, and through the injectors. The ECU isn't grounding them to complete the circuit to open them.

Seems like a back asswards way to switch the grounds instead of the positive side.

I'm also using a dual oil pressure switch by the distributor, same as the 1991 used. That's also new because the old one was leaking a bit. I'm sure I don't have the gauge and ECU sides of it swapped. Got a diagram for that?

If I can get this dually flatbed running, then I can get back to putting the rest of it back together. One sort of neat item, the dual shaft AM/FM cassette radio with digital tuner (was that ever hard to find these days) turns out to be the exact model of radio used by Lamborghini in the late 1980's. Stylin!

[brontotx]

Originally Posted by bizzybody

I forgot to mention that it does get power to, and through the injectors. The ECU isn't grounding them to complete the circuit to open them.

Seems like a back asswards way to switch the grounds instead of the positive side.

Seems backward, but switching the ground is easier (i.e. less heat generated) on the ECU than trying to switch 12V. Again, the ECU won't send a ground to the injectors unless it first gets a signal from the distributor that says the engine is spinning. You said that you had a new small cap HEI distributor, so here is a link for general information on HEI - your ignition module is the "B" model pictured a bit ways down. To troubleshoot the hall effect sensor in the distributor to confirm that a tach signal is being generated for the ECU when cranking the engine, see here.

Originally Posted by bizzybody

I'm also using a dual oil pressure switch by the distributor, same as the 1991 used. That's also new because the old one was leaking a bit. I'm sure I don't have the gauge and ECU sides of it swapped. Got a diagram for that?

Here is a link to a diagram... scroll down a ways to lucky post #13 and look at the third/last wiring diagram, where you will see the fuel pump relay oil pressure switch in the lower center. Terminal "A" (tan wire) goes to the instrument panel gauge, Terminal "D" (or "B"?; orange wire) is the 12V, and Terminal "C" (gray wire) is what goes to the fuel pump relay. Without oil pressure, you can unplug the connector and check for continuity between terminals D/B and C on the switch - it should show an open circuit. With pressure, terminals D/B and C should show a closed circuit. If the switch checks fine, I'd start giving the stink eye to the fuel pump relay.

Originally Posted by bizzybody

One sort of neat item, the dual shaft AM/FM cassette radio with digital tuner (was that ever hard to find these days) turns out to be the exact model of radio used by Lamborghini in the late 1980's. Stylin!

Vroom! Vroom!

[bizzybody]

Tach signal from the coil? I cut that off the plug to the coil because A. the truck doesn't have a tach and B. information I found on modifying original GM wiring said it wasn't needed for anything but a tachometer.

It has the two wires that go from the other connection on the coil directly to the distributor, and it will run with gas poured in, so there's no problems with the *ignition* part, the bug is in the computer connections, somewhere.

Is there a way to test the ECU to see if the circuitry in it that grounds the injectors is good? Anyone on this forum near Weiser, Idaho?

[brontotx]

Tach signal from the distributor, not the coil. There is a four pin plug on the distributor that needs to feed an "engine spinning" signal to the ECU before the ECU will ground the injectors - no ifs, ands, or buts!. On the link I sent previously to the wiring diagrams, the first page shows the ECU inputs and the "distributor" signal is the fourth terminal/wire (ppl/white) down shown on the left side. The second page of those diagrams (wire #2 on the left) shows this being terminal "C" on the the distributor's 4 pin plug. Without this distributor "tach" signal, the ECU won't ground the injectors.

Again, no "tach" signal and the ECU WON'T ground the injectors... in simple terms: (1) the ECU is "smart" enough not to dump fuel into an engine that isn't spinning and (2) ECUs of this vintage did not control spark (timing maybe), so pouring fuel into it and having it run (like you did) shows that the problem is not ignition, but something in the fuel/ECU area. As before, the ignition module is the culprit 80% of the time. Hope this helps!

[brontotx]

My mistake: two wires from the distributor to the ECU:
1. The ppl/white wire I mentioned previously/above, which is thr "distributor reference hi" terminal on teh ECU.
2. A red/black wire, which is the terminal below the one above and called "distributor reference lo" and connects to terminal "A" of the four pin plug on the distributor.

Both wires are needed for the tach signal that the ECU uses to permit grounding/firing of the injectors. The tach signal is also used to know the RPM.

[bizzybody]

Originally Posted by brontotx

My mistake: two wires from the distributor to the ECU:
1. The ppl/white wire I mentioned previously/above, which is thr "distributor reference hi" terminal on teh ECU.
2. A red/black wire, which is the terminal below the one above and called "distributor reference lo" and connects to terminal "A" of the four pin plug on the distributor.

Both wires are needed for the tach signal that the ECU uses to permit grounding/firing of the injectors. The tach signal is also used to know the RPM.

So if I have continuity on those wires from the ignition module to the ECU, then it might be a bad ECU?

[brontotx]

Originally Posted by bizzybody

So if I have continuity on those wires from the ignition module to the ECU, then it might be a bad ECU?

Correct, but personally, I'd give the stink eye to the ignition module and distributor before the ECU. And yes, I know that you said that you bought a new distributor. See this video here on "junk" aftermarket distributors versus GM and how to check them with a cheap LED (good information starts at around 3:30).

[bizzybody]

I kept the module from the original 91 distributor and tried it too. Would still run with gas poured down it but no injection.

[brontotx]

Have you confirmed that the ECU has power and ground (see diagrams linked previously):
1) System ground, Terminal A1 on the ECU via black/white wire to left top front of engine.
2) System Ground, Terminal A2 on the ECU via tan/white wire to left top front of engine.
3) 12V Ignition On, Terminal E15 on the ECU via pink wire to connection under dash to other pink wires.
4) 12V Battery, Terminal E16 on ECU via orange wire to connection in engine compartment with other orange wires and powered via fuse to underhood fuse/relay center in left rear of engine compartment.

While I quoted the "technical" locations for these wires, I do understand that swaps sometimes result in different locations. Nevertheless, terminals A1 and A2 should have an engine ground, terminal E15 needs a 12V ignition on feed (on when ignition key is on), and terminal E16 needs a 12V fused battery feed (on all the time).

[bizzybody]

My A1 wire is green with a white stripe and there is no A2 wire. I didn't remove any from the ECU plugs. I found a color diagram that nearly matches my wiring, shows the other ground at B2 with a tan/white but the wire is really solid grey. A1 and B2 both test good for ground. (Would have been nice if GM hadn't kept changing wire colors etc so often!)

There are no E terminals, only A on one side of one plug, B on the other side, C and D on the other plug. Numbers 1 up on each side, not evens on one side, odds on the other.

It's a 1991 system.

Originally Posted by brontotx

Have you confirmed that the ECU has power and ground (see diagrams linked previously):
1) System ground, Terminal A1 on the ECU via black/white wire to left top front of engine.
2) System Ground, Terminal A2 on the ECU via tan/white wire to left top front of engine.
3) 12V Ignition On, Terminal E15 on the ECU via pink wire to connection under dash to other pink wires.
4) 12V Battery, Terminal E16 on ECU via orange wire to connection in engine compartment with other orange wires and powered via fuse to underhood fuse/relay center in left rear of engine compartment.

While I quoted the "technical" locations for these wires, I do understand that swaps sometimes result in different locations. Nevertheless, terminals A1 and A2 should have an engine ground, terminal E15 needs a 12V ignition on feed (on when ignition key is on), and terminal E16 needs a 12V fused battery feed (on all the time).

[bizzybody]

Originally Posted by brontotx

My mistake: two wires from the distributor to the ECU:
1. The ppl/white wire I mentioned previously/above, which is thr "distributor reference hi" terminal on teh ECU.
2. A red/black wire, which is the terminal below the one above and called "distributor reference lo" and connects to terminal "A" of the four pin plug on the distributor.

Both wires are needed for the tach signal that the ECU uses to permit grounding/firing of the injectors. The tach signal is also used to know the RPM.

Purple/white goes to ECU terminal B5, Black red to B3. 1991 system. What year diagrams are you looking at?

[brontotx]

Sorry, the wiring diagrams I referenced were pre-'91. Here is a correct figure, which shows the distributor wires on B3 and B5.

[bizzybody]

The four wires from the ignition module to the computer connectors all have continuity.

The orange wires to the ECM are hot all the time. Shouldn't they be off with the key off?

A6, pink with black stripe, is not hot with the key on or when cranking. Where is the other end of that wire?

The fuel pump runs continuously with key on and cranking, even with the ECM disconnected. Shouldn't having the ECM unplugged prevent the pump from running?

Might this solve the problems?
http://www.ebay.com/itm/142075509473

[rfmaster]

Bizzy

1) A6 pin is the IGN-ON circuit (pink/gray or black/red depending on the year and application). This circuit MUST be connected to ignition hot circuit - i.e must be +12V when key is in RUN and CRANK position. It is a very common mistake to connect this circuit (wire) to IGN circuit that goes OFF when cranking!

2) There are two orange wires in the ECM interface:
a) ECM Pin B1 - this is a direct connection to the battery - always hot!
b) ECM Pin A8 - this is a data line used for ALDL interface.

3) Fuel Pump should only run when either ECM commands FP relay to close its contacts or if oil pressure switch senses engine oil pressure above 6 PSI give or take. Check your FP circuit wiring. Disconnect oil pressure switch to see if FP stops operating.

4) Ebay harness is nice, but factory harness should still work just fine.


//RF

[bizzybody]

B1 and C16 are orange and according to diagrams connect to the same source. As I said, they are hot ALL THE TIME. Key off, run, acc and starting.

Thus the ECM has power.

Would be nice if there's someone near here who could come and have a look and see what's not right with it.

[bizzybody]

I gave up on getting the stock 1991 ECM and wiring working and tossed $375 at Performance Fuel Injection Systems for an ECM and wiring harness, with the 700R4 transmission control and VSS input.

IT WORKS! Got the timing adjusted to 0 TDC and it runs great.

I did have to extend the wires to the distributor about 12" because of where I'd put the harness through the firewall, and to get the timing setting connector accessible instead of right down by the distributor. I also re-routed the ECM power and fuel pump power wires through the split loom so they would be out in the engine compartment.

Video of it running will be here when it's done uploading to YouTube.

https://youtu.be/CA6Q8PU7YNw

[Wwes]

I'm doing a 350 TBI swap into my 83 K10. the engine is out of a 90 C1500, I have a wire harness from a 90 Suburban, and the computer is from the same C1500 7787 with a code of AMUR.

The specific question relates to the dual fuel tanks.
-How do I wire up the in-tank fuel pumps (I have a 87 baffled tank, 87 sending units with the integrated in-tank pump). I cannot figure up where the wires from the sending/pickup unit pigtail attach to?
-Do I need to replace the fuel selector valve? I bought one off Amazon, and it looks exactly like the one I already have on the truck.
-Do I need to replace the fuel tank selector switch?

I also have a new fuel pump relay and believe I know how that works, but the pump wiring has me baffled. I did figure out the actual fuel hose routing.