This will be a bit long winded but I'm trying to give as much info as i can so you guys out there smarter then me can help me out hopefully. So as the title states I'm having issues with my 89 3VZ truck starting and dying then not starting back up. So my issues all started when I went out to drive my truck one day and it just would not start at all, no click, no cranking, nothing. I then let it sit for probably a couple months and drove my other vehicle around as I was busy. Then I finally got out to work on it and thought why noy just see if it'll run, well by my suprise it ran and seemed to run well. I went for a short drive with a few stops and had no issue but on my last stop as I was leaving it started up fine i started to take off then it died and wouldnt start back up. I towed it home and it sat overnight, i went out the next day and it fired back up but died out. When it died out it was acting like it was starving for fuel. After that i replaced the fuel pump it didnt help, then thought maybe it was the ignition coil, replaced that and again nothing and just today i replaced the fuel pressure regulator and again nothing. So this time i thoughtwhy dont i bypass the 2 pins in the diag port, so i did and it ran just fine but as soon as i pulled the wire off it stumbled and died out as usual. I should also add that the whole time the pressure at the fuel rail was reading 46ish psi which from what I read is right in spec. So now I'm completely confused on what else it could be, I'm sure one of you can help me out here. Its probably simple but i just haven't figured it out yet. Thanks in advance.

 

I'd start by checking the circuit opening relay and then the AFM. Both of those have a hand in the fuel pump operation

 

Yeah, sounds like the COR, or the part of the AFM that switches on when there's air flowing through the AFM, keeping the COR energized while the engine is running. Normally, it's the COR. They get old, and the contacts inside build up corrosion on them. If you pull the cover off the COR you can check them to see, but it's just as easy to simply replace the COR. If you want, you can then work on the old COR, cleaning the corrosion off the contacts inside. You may be able to make it a replacement for an emergency, if the new one fails in many years, but it's a lot of work, and may not even work. IMHO, not worth the effort. Look how long the old one lasted, presuming that it's the problem.
Also, check the area the COR is in, for water incursion. The windshield starts to leak into that area when it gets old. Easy to check. Have someone squirt water from a garden hose all over the windshield, and check inside the two kick panels, one on each side, for any sign of water intrusion.

Good luck!
Pat☺

 

Thanks guys, I'll definitely have a look and be sure to update with my findings

 

That is definitely not the COR-VAF circuit. Somewhere, you have a bad wire or connection, that when shook "open" deprives you of all 12v power.

That is diagnostic of an issue with the VAF-COR circuit. Here's how to find out where the problem is specifically: https://www.yotatech.com/forums/f116...-quits-312747/

Well, it's your money. And there is a very tiny chance that out of the whole VAF-COR circuit, it's just a bad COR. But do you want to drop $112 https://www.toyotapartsdeal.com/oem/...910-35010.html just on a guess-and-by-golly? How did replacing the fuel pump and ignition coil and FPR work out for you so far?

 

Weird in that you get nothing at all to bypassing the COR, and it runs fine, but dies as soon as you stop bypassing the COR. You can get a Denso made in Japan COR for $41.51.

 

i just ordered that one off amazon earlier so we'll see when it gets here in a week or so.