88Mr290Pickup

First of all, thank you for the help you fine folks have already given me, via previous posts. I’ve come, hat in hand, to plead for more assistance with my very first post, and I apologize for it.

Back story: I bought a ‘90 3VZE powered Yota basket case truck. Engine was newly rebuilt, but came as a long block sitting in the bed of the truck, and several boxes of parts. I have since finished assembling the engine and installed it in the truck.

Problem: Engine is not running. The engine will crank, start, and as soon as I release the key from the start position, die.

What I’ve done: I’ve verified that the engine has spark. If I spray carb cleaner into the intake, the engine starts and runs as long as I keep spraying in carb cleaner. Obviously a fuel problem. Fuel tank is half full of gas, as verified by the fuel gauge and the 8+ gallons I dumped in. VAFM checks out per FSM, including the fuel pump kick on circuit. Manually holding open the VAFM flap or jumpering B+ and FP in the diagnostic port causes the fuel pump to kick on, I can hear it and feel the fuel lines vibrating. I removed the fuel return line and stuck it in a jar while jumpering the fuel pump, plenty of fuel came out of the fuel return line. Obviously this only guarantees that the injectors are seeing fuel, not the correct fuel pressure. I reconnected the fuel return line and pulled the cold start injector, stuck it in the same jar, and cranked the engine. CSI had a good solid mist to it, not a drip or a stream. Fairly certain this is the only fuel the engine is getting. I have verified that the ECM is getting power and ground. I have checked extensively for vacuum leaks, and have eliminated the PAIR and EGR systems. I have verified that the engine and the fuel injection harness is grounded. I have replaced the piping between the throttle body and the VAFM, eliminating all the resonance chambers but retaining the stock air filter and air box.

Plan of attack: This is where I get hung up. I would like to verify the VAFM inputs at the ECM, and the injector outputs at the ECM. I have the ‘93 FSM as listed everywhere, and my truck is a ‘90. The pinouts on my ‘90 ECM don’t seem to match with the pinouts listed in the ‘93 FSM, so I’m having trouble figuring out just where I should be poking and testing. Places where the ’93 FSM shows wires for the ECM, my '90 ECM has a blank spot w/ no conductor. Is the ‘90 ECM different than the ‘93, or perhaps the FSM is for the Cali emissions version and mine is fed/Canada? I’d like to test fuel pressure, but I’d prefer to check these other things first, as they are free and all indicators show that I have fuel pressure sufficient to get the truck to at least run.

I have searched through these and other forums, I have pored over the FSM. I have searched here in the forum and started reading down the line, checking anything that may be a possibility with my truck. My current daily driver is not at all suitable for the ice and snow that is soon to come, I would REALLY like to have this truck running before then. Any help you folks could give would be greatly appreciated.

Thanks all.

Edit: I've since pulled the injector power plug off the driver's side forward injector and measured voltage at the plug. Battery positive on both terminals, pulsing when cranking over engine. This seems to indicate that the injectors are getting power. I'm leaning towards fuel pressure again, and looking into a fuel pressure tester.

88Mr290Pickup

Nothing? Does anyone agree w/ my diagnoses, or have any thoughts at all?

How about a good deal on a fuel pressure tester and Yota banjo bolt adapter?

Thank you all.

88Mr290Pickup

Borrowed a fuel pressure tester from Autozone, fuel pressure tests out perfect. 45psi sitting w/ fuel pump jumpered in the diagnostic plug. Goes down to 40 while cranking, pops right back up as soon as the engine fires. FSM specifies 37 psi while idling, so 40 psi should be plenty enough. Engine still dies immediately.

Anyone have any thoughts? Really surprised, lots of views, no one has any ideas? Should I have posted this somewhere other than the newbie tech section?

Thanks again.

Edit: I also pulled the trouble codes from the ECM, got zilch. Just for S&G's, I tried starting without the AFM connected. Cranked, wouldn't cough. Jumpered the fuel pump, tried to start again with the AFM disconnected. Same exact symptoms as my original post. Anyone have a known-good AFM they'd be willing to sell/rent me?

93toyrunner2

Where are you located? People nearby may be willing to assist you with diagnostics, if they knew where you were.
First, Do you have spark?
Second, Grounds - Do you have good ground?
1- Passenger side fender well next to battery tray and fuse block
2- Drivers side from igniter wiring loom area to drivers side manifold (also check and clean / wire brush underneath the igniter where it bolts to the inner fender well.)
3- back passenger side of top of block to firewall - the injectors ground out to the same bolt on the back of the passenger side valve cover. Do you see this ground from the injector harness to the valve cover, then a separate wire from there to the firewall?

93toyrunner2

Check the above connector at the ecm and measure your continuity from pin 12 (white/red) wire to the injectors white/red wire on all the passenger side wires. Do the same thing from pin 25 to the white wire to the 3 drivers side injectors. I had issues with old wiring, and ended up just running new wire to fix it.
Test your ground from the injectors ground wiring loom to the frame/firewall. Do you have good ground / continuity?

88Mr290Pickup

Thank you, Bob!

I will go verify the connections you've shown.

Thank you again!

88Mr290Pickup

All grounds are present and in good order, as verified w/ a DMM. Zero resistance between driver's side injector and ECM, trying to find a way to verify passenger side w/ out yanking the upper intake.

On an interesting note, the driver's side injector that I can access has full batt + on both terminals any time the ignition is turned on. I completely unplugged the ECM, full batt +. Yank the EFI fuse and relay, still full batt +.

There was a car alarm and aftermarket stereo in this thing that I disconnected and removed, I'm wondering if some monkey didn't mess with some other wiring. If someone connected batt+ from a key-on source directly to the injector harness and terminals of the injectors are seeing full batt + all the time, then whatever ground the ECM provides to trigger the injectors won't matter. This could be my problem right here.

Thank you again for the help, Bob.

Edit: Never mind, I figured out the batt+ thing. Looks like the injectors DO get power directly from the ignition switch, although pulling the EFI relay and fuse and still getting power is odd. As for full batt + on the ground terminal, I only disconnected one injector plug, the other two injectors on that side of the circuit could easily be supplying batt+ through them. 13.7 ohms cut in half (two injectors) would still provide what looks like full batt + at the miniscule draw of a DMM.

I'm going to be sorting through the distributor pickups now, to make sure the ECM is seeing that the engine is actually spinning.

Thanks again.

88Mr290Pickup

I yanked the intake manifold. All injectors test out to have correct continuity. If I unplug two injectors per bank and, with the key on, supplying power to one side of the injectors, and ground the other side through one of the other injector connectors, the one injector that is still connected will click and open. (Do not try this on low impedance injectors.) The passenger side, all works well. Driver's side, nothing. I ground one side and get nothing. Looks like a problem w/ the driver's side injector wiring harness. I am slowly getting closer.

93toyrunner2

If you unwrap the driver side wiring harness for the injectors, it leads back to a coupling near the passenger side wiring, just before it breaks off to the passenger side. They all 3 feed off the same base or initial wire feed. Test continuity from the ECM to the area of the splice (were it goes from 1 wire to the three wires). You may find your problem there.
Splice in a new wires connecting to the main wire from the ECM (or run a new one from the ECM as needed) and solder them for the drivers side. I recommend using shrink tubing after a good solder job, just to protect them from the elements.
Glad to see your getting there!

88Mr290Pickup

Thank you Bob!

I have torn the intake off and taken apart the injector harness. Lots of corroded connectors, and lots of wire that is corroded inside the insulation. A couple injector plugs having intermittent connection to the main bundle. Not going to mess with any of that, not interested in doing spot fixes and having to rip the intake off every time there's another problem. I'm going to build a new injector harness from the ECM out to the injectors, new plugs and everything. I am not certain this is the problem I am having, but it is definitely a problem, or shortly going to be a problem, and I want it out of the way.

I'm having trouble finding injector plugs. Dealer says NLA, my favorite Napa says the same thing. I'll be searching this site and others for the best place for injector plugs. I work in an electronic components warehouse, is there a standard Molex or Amp part number I can order?

Thank you again Bob, your help has been invaluable.

88Mr290Pickup

Update!

Have completely rebuilt the fuel injector harness from the ECM out to the injectors. New wiring, new connectors, everything. All the testing that was giving me fits and driving me insane earlier now tests out perfect. I hooked up the fuel return line and the cold start injector, jumpered B+ and FP in the diagnostic connector, turned on the key, and manually grounded the injectors at the ECM plug. All six injectors got power, only four injectors fired, and those that fired obviously squirted different amounts of fuel. I need new injectors.

Deep breath. 10...9...8...7...6...5...4...3...2...1.... Deep breath.

I should have gone with a Mercedes diesel swap from the very beginning, and never even looked at this 3VZE. For what I've paid in $$$, sweat, and hassle, I could have swapped in an OM617 and gained much reliability, simplicity, and fuel economy. The OM617 turbodiesel is the engine I've wanted all along. The plan was to install the 3VZE, drive it through the winter, and then swap in the diesel. Things did not go according to plan, it may well be summer again before I actually get this truck going.

Thanks everyone for your help.

93toyrunner2

http://witchhunter.com/
Send them your injectors and they will fix them up for you! Cheaper than buying 1 injector reman from the auto parts. Do you have a good ground from the injector harness at the pass rear of the valve cover? There is a ground there from the firewall and from the injector harness for both sides. Check continuity from the block to the firewall. Did you replace the ground wiring included in the injector harness you mentioned you have replaced?

88Mr290Pickup

Thank you sir!

I did replace the ground wires. My understanding, and what the existing wiring harness showed, was that the injectors all receive batt + from the same wire that powers the ignition system, and receive batt + all the time the ignition is on. The other terminal on the injectors is then grounded by the ECM to trigger them. The grounds near the passenger side valve cover are in good condition and hooked up as they should be. There is the same resistance between the block and the firewall as there is between the leads on my DMM.

Thank you for the Witch Hunter Performance link. I was going to buy no-name injectors online for $35 a piece, now I will have my existing ones cleaned.

Thanks again.

93toyrunner2

Looking forward to the outcome. Please keep this post updated as you progress.

88Mr290Pickup

Yessir, will do. Thank you for the help!

88Mr290Pickup

Just an update:

My injectors should be back from Witch Hunter Performance tomorrow or the next day. I should be running a day or two after that.

Thanks again folks!

ThurzNite

I'm having similar problem of starting, but doesn't stay on longer than 10 seconds, then dies. Subscribing for updates. Good luck!

93toyrunner2

Check plug to your AFM.

88Mr290Pickup

Starts on the first crank. Idles beautifully. Revs smoothly.

So much bottom end rod knock it sounds like someone forgot to put bearings in one of the connecting rods.

Not sure what the plan is now. Would love to yank the motor and proceed directly with the Mercedes diesel swap, but money is tight and time is short.

Pretty discouraged right now. First time I have EVER trusted someone else's rebuild, and now I know why. Any ideas?

93toyrunner2

Compression test on each cylinder. Should be 141 to 172 each cylinder. If one is much lower than the others, add one teaspoon of motor oil, and retest it again. An increase in pressure shows rings/piston issues. No increase, possible valve stuck issues. This should help you determine if the top end is any good.