Steve777

More updates:

Tried playing with the timing, found that it ran a bit longer with the dist rotated 1/8" CCW (measured at the hold down bolt). Gives a sec or two more run time.

Double checked the AFM and it is in spec on the resistances. Also checked the harness add-on (PO replaced the stock air filter and tubing with a K&N filter and moved the AFM over next to the battery). They did a professional job of extending the cable to the AFM, but I figured that was a likely source of a short. Unfortunately no problems, good low resistance connection from the connector back to the main wires. BTW, does the AFM care which side is up? And how if the factory orientation of it?

Tried moving the idle screw setting without much effect. (Sign of a vacuum leak, seems to work best 1/2 turn up from all the way down?)

One thing I noticed is that for the few seconds it runs now, there is a definite pattern. It starts up just fine, then as soon as the RPMs touch 1000 on the tach, it starts dying. As it slows down below 1000RPMs it starts running better again to repeat the sequence as it gets up to 1000RPMs again. So it seems that there is something the ECU is trying to do at 1000 RPMs that is killing the engine, maybe. Any clues here as to what might happen at that engine speed?

So its back to rechecking the vacuum hoses. Also seems possible that a stuck EGR valve may be a source of vacuum leak?

Any other ideas?

rochound

i have 1990 22re with the same problem i replaced the efi relay and get fuel pressure but like yours 2 seconds and dies . definitely not a spark issue it will keep running on ether . ive checked injection power at computer and have voltage ,also the coil+ feed to the injectors and has power. ther are three wires coming from coil igniter to the computer these must? tell the injectors
when to close circuit and inject fuel ? also when i tryed to do a self test all i get is a blink every second continuously with no interuption not sure what thats about. im starting to think the cpu or igniter is faulty.
ive on other brands of electronic ignition but this design is a bear

quiggs12

I am not telling you that this is likely... but it did happen to me, but only two cylinders. My truck was purchased exactly like yours (not running) and at one point my injectors (only 2) got stuck open somehow and it was flooding out those two cylinders. It is possible that your injectors are stuck open and it runs for a few seconds until it floods itself out. Or maybe they are leaking enough to flood them out. How long did the PO say the truck sat before you bought it???

Steve777

Entirely possible, the stuck injectors flooding. I am seeing gas/wet on the plugs when I pull them. And there is a gas smell after its short runs (like a rich running engine). Seems like a worthwhile avenue to pursue. I am going to see about getting the needed fittings for doing a gas pressure test, and if that is normal I think an injector check should probably be next. Truck sat ~2-1/2 months before I got it.

Can any of the experts here chime in: If one has a big enough vacuum leak to kill the engine, is the engine dying of too lean a mixture (which seems like the obvious way it would go), or by some fluke of how the EFI interacts does it die too rich? Be good to know so I can decide whether to recheck for vacuum leaks yet again or start down the fuel/leaky injector path.

rochound, I'm not entirely sure for a 90, but on my 87, the code I was getting before I cleaned the TPS was an 11. That was 11 flashes in a row. From the little in I have on the later trucks, a 90 doesn't do as many flashes in a row, but flashes out two digits (1-7 each) with a slightly longer wait to separate them from each other. From the Haynes manual I have a constant on/off with no pattern is normal for an 88+ model, eg no errors (which is what I get in my 87 now (it's a 1 there). If you can run on ether (I can't), then it sounds like lack of fuel; might try jumpering Fp and B+ (I think those are the ones to force the fuel pump to run whenever the key is on) and see if that makes a diff.

sam333

Do a fuel pressure test,( static and under load) its one of the first things you should do. Also you can tell if you have leaky injectors( if it wont hold pressure once you turn the key off off).
Also a spark test while the engine is running( pull one plug and run it till it dies and watch to see if you are loosing spark. You are going round in circles.

Steve777

Fuel pressure is in range (44psi with the Fp jumpered not running, 36 while running and moves up when the vac hose is pulled from the pressure regulator.

After turning off the key, pressure drops roughly 2psi per min and stablizes around 30psi or just under. Normal or should I be looking for a leaky injector(s)?

BTW, Autozone here will lend you a fuel pressure kit for free (you buy it and they refund your money when you return it). Their fuel injection pressure kit has the right fitting for tapping in at the CSI. Thought that might helps some people.

Put a vacuum gauge on the plenum to see what it looked like. Pulled a steady 12 Hg/in for the short time it ran, throttle closed. Tee'd the meter into the vac line that runs from the plenum to the "valve" on the PS pump. That seems low, even for 8500' elevation (I would expect maybe 3-5" less than at sea level). So possibly back to a vacuum leak, what do folks think (I don't have a running 22RE here to compare any of these reading with)?

Spark appears to be running right up to the time it dies.

Suggestions for where to look next?

Thanks.

Steve777

Holidays and weather here kept me from doing much until today.

Thought I would go back and clean all the grounds on the engine; they all seemed to be in place, but WTH. After taking them all apart, shining them up and reassembling an amazing thing happened; the engine ran. Not great, idle sounded like it was only firing on 3 cylinders, but it ran. It would rev easily up to 2-3K where it was pretty good and idle back down. Stopped it and restarted it a few times. I was ready to declare victory after about an hour (at least a partial one) and then while idling it just died. After that it was back to before, starts and runs for a couple of secs and dies.

All the grounds are still clean and tight, so it's not that. I am guessing that I moved something during the ground cleaning earlier and some wire now was no longer open or shorted for the hour of running or so, but the vibrations put it back and now it won't run again. Tried moving the harness around to see if I could find the "magic" one that made a difference, but no luck.

Seems like the next step would be to take the intake plenum off and check the wiring under there, as well as the injectors.

Besides the injector splices, any common failure points on these things to look out for?

Any other things which these symptoms might point to?

Thanks guys.

TNRabbit

Pull the vacuum line off the EGR for a minute & see if that helps; if so, it's the vacuum modulator that's your problem:

Steve777

Got the runner inside which helps alot as it is -2F with 30mph winds right now.

Took off the intake plenum and started checking out the injectors/wiring. First test was putting the CSI back on the fuel line, and jumping Fp and B+. Let the fuel pump run for 2 minutes. No leaks from the CSI, but I did smell some gas from the intake so perhaps a leaky cylinder injector (have not pulled them yet to check). All the injectors have correct resistance, and all will click if touched momentarily to a 6v 2A battery charger.

Put a 12v 194 12v light bulb into each injector socket, no flashes while cranking (could be the 12v 194 dash light is too big to flash on the short pulses the injectors get, will try to pick up a real noid light tomorrow). With the ignition key on, i measure 12v on one side of the injector connectors, the side which goes to the resistor pack on the sidewall of the engine compartment. The other side of the connector is at ground; that is I can get 12v between the two sides of the connector measured with a volt meter, but they don't flow enough current to light the 194 bulb (this all with the ignition key to run). I also get 12v between the resistor pack side and battery ground too.

So this is what I think this means (please correct me if this is wrong):

The connector side that goes to 12v through the resistor pack seems OK.

From reading other posts here, someone said that the ECU holds the "other" side at 12v too until it wants to fire the injectors, when it momentarily grounds that side to fire fuel in. So since I did not measure 12v at any of those other sides on the connectors with the key on, I am thinking those wires are either not connected to their ECU pins anymore (a short in the wiring harness) or the ECU is broken.

Could someone confirm that I should have seen 12v on both sides of the injector connectors before cranking and with the key turned to on?

And from other threads here, it seems likely to me that the break in the injector wiring would be the junctions in the harness under the plenum. Other places to look?

And on another note, While this was setup, I plugged the connector back into the CSI to see if it was spraying on cold start cranking. It sprayed fine, and I collected about 1 tablespoon or more of gas from 3 sec of cranking. That seems like alot of gas for that short a time to me. Anybody know if that seems right? (FWIW, garage was probably about 40F at the time).

BTW TNRabbit, EGR valve is ok. bypassing made no diff in the starts and dies. And now with the plenum off, I have tested it and can't blow thru it when it should be closed.

Thanks Guys.

Steve777

The runner is running finally.

Thought I would post the final results and what I learned, in case it might prove useful to others. The confounding thing with this was that several things ended up being broken at once, including some that steered me away from the other problems.

Ultimately the main problem was that the electrical connection where the ground lines to the injectors return to the ECU were totally corroded away inside the harness at the junction. Barely a strand of copper left, although enough to run 3 cyls for that hour after I moved the harness just in the right way that one time. Additionally at least one injector was leaking a bit, so even without any signal to fire it could wet the spark plug, leading me to think the injectors were firing when they weren't. (Of course, if I had more experience with 22REs, I might have recognized that the injectors were not firing from their sound, but will know that for next time). Another confounding thing was that the wiring harness was still full of water; it came dripping out when I unwrapped it. No doubt this water caused the corrosion, and some of the odd electrical readings I was getting, as it provided a high resistance short to ground inside the harness.

So basically, I ended up taking off the plenum, checking the wiring and unwrapping the main harness, looking for the infamous junction that always corrodes. BTW it is at a low point on the harness, almost as though they designed it to collect water and rot out. I cut out the rotted wires, up to a higher point, patched in some replacements. Cleaned the other junctions in the harness. Dried everything out, and insulated and re-wrapped it. And put everything back together. Engine runs fine, all 4 cyl's fire, no hesitation or bogging.

I decided not to pull the injectors just yet because first I was anxious to see if the engine would run, and second I wanted to see if a few tanks with sea foam might clear up the leaking. Also there are a bunch of other things which need doing on this truck, and I wanted to get it moving so I can get tho them too.

So in hindsight, here's what I learned that might be useful to others in similar circumstances:

1. Just because your spark plugs are wet with gas does NOT mean the injectors are necessarily firing.

2. Running for a couple of secs and dying at start is very likely no gas getting to the cylinders at least from the injectors.

3. Listen to your injectors firing when the engine is running, so you'll know what they should sound like when they aren't working.

4. If you are looking for the junction in the wiring harness for the lines that go from the injectors to the ECU (E01 and E02, IIRC), that is located in the harness at roughly the low point between where it comes out from under the plenum and where it starts down the inner fender, the bottom of that loop. It's not under the plenum, so no need to pull the plenum and unwrap the harness in there.

5. If you are dealing with possible electrical issues in the harness, don't get too excited about weird readings, as water or other shorts in the harness can cause some really strange numbers to show up.


Thanks again for the help and suggestions on this.