1986 stalling issue

[Metalghost]

MarkH,

Progress. I pulled the cold start and it didn't turn over at all. Then I tried spraying starter fluid (not for long) into the air cleaner hose. Once with the flapper pushed and once without. Both times it ran great and stayed running. I also have checked fuel at the cold start connection with 45 PSI and assume the pump filter and workingfine. ALso assume it in the rail since I can hear the pressure regulator give some back to the return.

So, I think I am looking and the fuel injectors are not doing their job. This thing did sit for a very long time. I am going to try and confirm by letting the engine stall and pulling the plugs to see if they are wet and putting 12V on the injectors to see if they actuate before I jump into a fuel injector change, I want to be sure.

My only issue is I can't tell is if they plugs are wet, then is the problem the volume is right (or too much). Or worst off is the ECU is doing something to cut off the injectors after it starts up.

Any ideas before I go big on changing the injectors?

Thanks, and feeling encouraged now that I know it can run...

[MarkH]

I've never done this before so I don't know if it would work, but maybe try disconnecting the wiring to the injectors, putting a volt meter on the wiring, try to start the van and see if there is a voltage coming from the wiring. I'm not sure if you would get an accurate reading from a digital voltmeter since the signal is in pulses, but an anologue meter (with a needle) should show a voltage. That would tell you that the ecu is sending a signal. There should be a way of testing the injectors (resistance, etc.) according to the factory service manual. I'll check when I get home and post the pages. The cold start injector can be removed from the intake and tested by starting the van and watching the spray pattern into a glass jar, but the main injectors might be difficult without rigging up some kind of test manifold. I'd be surprised if all 4 injectors failed or were clogged all at once. My van sat for 8 years in a field before I got it. The fuel in the tank was like varnish. With new fuel/filter/pump, the old injectors still worked fine.

[Metalghost]

MarkH, I found the resistance test. Basically between 3-5ohms. The ones I could get to were good. cols start, and #1 and #2.

I am also suspect on all 4 are plugged or stuck. But I am sure that I have fuel on one side of the injectors. Just not sure why they aren't getting to the other side. I worry this is an ECU issue or worse wiring in between. I'm going to try and wet the plugs first with the cold start unplugged. I dread if they are wet and somehow the injectors work on cranking but not idling. It does turn over so I know one or two are firing so maybe one or two are working and 2 aren't. I am going to try everything I can to verify the injectors before I tear into them.

[MarkH]

006_EFISYSTEM.PDF
I attached the EFI portion of the factory service manual for the 1986 vans. The picture below is from page 36 I think:
Here are some pictures from the same manual for physically testing the injectors. This test seems like a pain since you have to rig up some new piping/hoses:Attachment 11863Attachment 11862Attachment 11861

[Burntboot]

In addition to what MarkH has highlighted, you may want to have a read thru this thread and confirm the tests that Tim suggests

Thread: fire but no fuel (been sitting for years)

[Metalghost]

Okay. Getting closer.

Got a noid light and plugged into the FI1 plug. No signal while cranking. Tried FI2 and same. So the injectors are not firing due to lack of a signal. Checked the plugs and they are fairly dry. I think the cold start injector works. Which would explain it turning over then dying.

Need to make some measurements but I suspect the ECU. There is 12V on one side of the plug and the other is no voltage. From the diagram I think both would be high if the other plugs are in.

Strange thing is. I don’t see or measure anything wrong with the ECU. Ideas in ways to check the ECU before I buy one to try?

[Headhunter38]

I would at least open it up and see if you can visually see anything wrong. It might be repairable.

[MarkH]

According to the wiring diagram, the cold start injector doesn't go through the ECU so that would explain why it is firing and not the main injectors. Here's the link again to the section from the factory service manual for the fuel/ECU system:006_EFISYSTEM.PDF

Here are the relevant pages for testing the ECU terminals:

A quick check would be to check that the 15A EFI fuse isn't blown and the ECU is actually getting voltage.

[Metalghost]

Status

When key is in run position

The ECU is getting the proper 12V power supply. As it should be.

At the FI1 and FI2 plugs I am measuring 12V on both pins. As it should be.

But with the either FI1 and FI2 plug out I am seeing 35ohms unplugged between +B plug and ignition. So I think I have leakage path there. Not sure this is enough to keep the ECU from pulling down the 12V and fire the FIs.

I have a friend coming with a scope to see if we can figure out if the ECU is doing it's job. But Frankly I"m in a bit of disbelief, this was the last thing on the troubleshooting list and would be surprised if an ECU went out over something mechanical. But currently where I am at. I know for sure the FI are not firing. Assumed that it is not getting the power pulse to actuate the solenoid. So ECU right? or is it possible the ECU isn't getting the signal about cranking and to fire the injectors?

I did try to start it with the pump test connector jumped. Didn't help but wasn't surprised as the pump runs but it just sits the rail.

Any thoughts out there?

[MarkH]

I'm not aware of any details about how the logic of the computer works (I don't think it's in the manual), but if some signals to the computer are not there, the computer should still let the van run in a "limp home" mode. For example the 02 sensor and airflow meter, etc. I assume there are still some signals to the ECU that have to be there for the injectors to fire. I'm guessing that the starter signal during cranking should be there otherwise the computer doesn't know that you are trying to start the van. I'd try and verify the voltages at the ECU terminals as much as possible according to the Factory Service Manual in one of those pictures above.

[MarkH]

Particularly the STA-E1 should have 6-12V during cranking.

[Metalghost]

Got through the troubleshooting checks for the ECU. All the inputs are per range but there is no signal triggering the FI coming out of the ECU. I even shorted the pin to ground to check the wiring to the FIs and when grounded it does pull down the 12v on the FI and fires them. But for some reason when cranking there is no signal/pulse generated from the ECU to pull down the 12V. Got the scope out and chased down the no signal all the way back to the main chip. But still hard to say the chip isnÂ’t producing the pulse or if it is still missing an input. I am being led to the ECU being the issue but the only thing nagging me is that the ECU looks fine and no burned up parts or broken components, no errors. So without seeing anything wrong I donÂ’t have any evidence (aside process of elimination and being out of ideas) that the ECU is the issue. Already covered the basics and pump works and have 36PSI at the rail, 15A breaker is good(checked with continuity), the open circuit relay is right and feeding power to the pump.

Anyone know what tells the ECU to start sending the signals to the FI? Is it a signal from the distributor? Would make sense as it has to be timed and if the dizzy is spinning then FI should be going too.

[Metalghost]

Sta-E1 was good just under 12V. 11.5v.

The AFM was also good in open and closed position.

TPS was good open and closed.

Ground was solid.

[Metalghost]

Finally figured it out.

After going through the TSM troubleshooting and doing the last ditch "try another ECU". There was still no change. I knew there was still no signal to the FI from the ECU but not sure why. All the inputs the TSM listed were there. But after thinking about it and the troubleshooting there wasn't any mention of testing the signal from the distributor/ignitor to the ECU. We saw an ING and IGT signal but there was a white wire coming off the ignitor called Ne. So chased that and saw the wire was not ohming out. Dig out the bundle and saw the problem immediately. The bundle passed through a sheet metal hole and the protective cover came off and the wires had been slowly cut the white Ne wire. Patched that break up and turned the key and it fire up fine and is running great now. So, this single wire that wasn't really covered in the TSM can be a source of no FI signal. I had to look up the Ne wire purpose on another Toyota site but sure enough it input the signal that was the FI. https://www.toyotaguru.us/engine-control-systems/input-signals-required-to-pulse-
Anyways van is running strong now. Thanks for help and hope this helps someone else out there.