[SOLVED!!!] What's the strangest reason your truck wouldn't start? (Yes, I need help)

were you getting spark from the distributor finger? Have you tried starter fluid yet? I didn"t read if it is cranking but not turning over either? I hope you solve it soon for your own sanity.

 

Shit. Wtf?

 

You will figure this out. How much dielectric grease did you use? Maybe try removing some or all of that grease. Doubt that's the problem. It's free to try though.

 

I bought an 89 Mazda b2400 that sat for years because it didn’t run. Looked underneath and saw a ground wire rotted off the starter to the frame. I sanded it clean, screwed it to the frame gave a Hail Mary, twisted the key and it started right up and run beautifully. You got this! Good luck!

 

Given that you're confident in both fuel and air, as well as the majority of the electrical system, this seems like a major red flag. I understand you checked resistances etc. and it seems "good", but the brains themselves could be sending/not sending the wrong messages because of a difference in the ECU's that you couldn't physically see/check. Maybe I missed it somewhere, but why did you buy a different ECU? Was there a problem with the old one?

I would also echo the comments about triple checking every ground you can find, even ones completely unrelated to components you're working on. A funky ground on something could easily be messing with the electronics.

 

Might sound simple but have you pulled the distributor cap off and see if distributor is spinning while cranking the engine? You may also want to see if you can install a NOID light in injector connectors to see if the are getting a pulse voltage.

 

Basically he isn't getting any power to the spark plugs and thus, no spark. He is getting spark to the distributor, but not to the plugs.

 

He said he had power at the distributor which I take to mean 12 volts at the connector, but it sounds like the ECU is not giving the signal to fire the ignition coil.

 

I broke both wrists and couldn't turn the key.

Other than that, only times it didn't start is when my battery died a couple times from sitting too long (may or may not have been related to broken wrists, lol)

 

If everything else checks out ok, I would get a pinout wiring diagram of your original year, engine, computer and compare it to the new year, engine, computer that the new engine is from. Just a hunch but maybe wiring pin locations are different from the original computer to the new one. Also check all power and grounds to computer after comparing and checking Wiring diagrams.

 

I know nothing about distributor equipped 3RZs, but is it possible the distributor is 180* out of position?

 

Best advice so far, they changed the pinout and ecm every damn year. Did you hear this motor run? You said the harness was aftermarket? If so I would start by checking that wire by wire. Don’t worry about fuel or air till you have spark. You need to simplify your thinking. Test and check each circuit on the most basic level, it’s usually a simple fix like a ground that didn’t get connected or a pinched wire

 

Whoa, thought I was on reddit for minute...nevermind.

 

This is the internet, so...

pretty much the same thing.

 

Pretty comprehensive suggestions here. I agree with with the ECM idea. There has to be a compatibility issue somewhere. If all the connections and grounds check out it has to move to the electronics not getting/sending the right signal.

 

I thought i was safe after leaving reddit. I thought I’d never have to think about that story again...

 

Wow - I was away for a day and you guys piled on the suggestions. Thank you, I appreciate it. I'm working with Tech support from ORS regarding the harness. If none of the "easier" suggestions pan out, I guess I'm looking at a pinout. I've done some of it already, and the ECU has the proper voltages in the proper places, but that doesn't mean one of the other pins isn't where it is supposed to be.

It's a 1996 Japanese T100 3RZ, which is identical to the Tacoma 3RZ except for the oil pan, the weird oil level sensor on the oil pan, and a lack of emissions equipment. It was "guaranteed" to run, and was running before removal. The engine itself looks almost new. Pulling the oil pan and valve cover showed beautiful internals. Granted, it could be a Taco engine, but from what I have learned, the rear sump oil pan and lack of emissions gear identifies it as a T100. Still, it's a 3RZ with the proper wiring harness and ECU.

Pending any suggestions from the harness manufacturer, I'm going to see if starting fluid works (headed to the store shortly). Someone suggested that perhaps the injectors shooting fuel provides a reference signal to send spark, or vice versa. Seems logical - I just don't know the ECU programming logic well enough to know if it is true. This suggestion seems to be good, since after cranking the plugs aren't "wet". Pending any other "life" requirements getting in the way, I will complete this test in a few hours.

Thanks again for all of your suggestions. I hope this thread provides useful information for someone else in the future. I think it will.

 

Not likely. I set TDC on #1 with the timing marks on both the crank pulley and the cam gears. Slid the distro in and at about 12 O'clock and it turned right to #1. But, it was definitely something I checked!

 

It has been my training over the last 35 years that in GENERAL, crankshaft position sensors are used to trigger a signal for the computer system to trigger signals for your “spark/distributor system”. The camshaft position sensor is used to send a signal to the computer system to trigger fuel injectors. I may be wrong, but I have never heard of using spark to trigger fuel injectors.

 

Good to know, thank you. It's my understanding that the 5VZE uses a separate cam position sensor, and the 3RZ cam pos sensor is integrated with the distributor. It's unlikely to me that both cam position sensors are bad in both the old (which tested good by all accounts) and new (same) distributors would both have bad sensors in them. But, nothing is impossible. I just got a Noid test kit and some starter fluid. Fingers crossed that I learn something new/useful from using them.