So farther into the rabbit hole I go. I have now tested and changed the circuit opening relay, the main efi relay, the fuel pump, mass airflow sensor, and checked fuses and continuity threw out the relays. Everything is getting power like it should except the fuel pump. It will not send fuel. A guy at Napa auto parts told me about a roll over valve that's piped into the oil pressure sensor somewhere and that valve will disengage the fuel pump if it thinks it has low pressure or if it gets a little piece of mud in it. I have no idea about this valve abd am wondering if anybody has any clues before I rip it apart and make it a 22r and just ditch all this electrical relay and vacume crap.

 

when testing the main efi relay to see what was what we determined it was bad and tried bridging power from right there. when I turned the key I got fuel for a second and never again. now I have replaced that relay and no fuel. could I have popped the open circuit relay again by bridging. check the relay it is good everywhere except to the fuel. when I turn key the truck will start for a split second just from pressure. and for that split second the open circuit relay will go from no voltage to 9.67 volts then truck dies and back to no volts.

 

it almost sounds like u might have some oxidation problems in a connection some where. see if u can follow on the wiring diagrams of where the power wire comes from and goes for the main relay. also do a search here i know there was a couple other people that had a problem not getting gas. doing almost the same thing as ur is.

 

https://www.yotatech.com/forums/f116...l-pump-230687/

heres one that is the same issue u are having.

https://www.yotatech.com/forums/f131...oblems-231710/
this one has more info about the relays

 

Thanks for the links. All the wires are fine. I have traced them all and the connections are fine as well j have all the diagrams and just can't figure it out. Gonna try the open circuit relay again and that's my last shot before going back to carb

 

Irishman....

Sorry you're having issues. I chased my tail for quite a while on several things in my build thread. So I know your frustration, believe me. I can see the point for some in going to Carb, but I just can't see ya giving up just yet, ya know?

It's very possible, yes, that you FRIED something by adding a bridge that doesn't belong. Not sure, but possible, ya know? My buddy's EFI main was getting hot as hell, couldn't hardly touch it-hot, ...and he wound up having a bad wire in the loom that was shorting out across another HOT wire..... Another guy, the fuel pump wouldn't engage because the Air Flow Meter was not engaging when the Door/Gate was opened(IT TESTED FINE for resistance, at least within specs....but the mechanism that completes the circuit inside the AFM when the door is opened.....FRIED) Replaced the AFM in the parking lot of a yard, VOILA, it worked. ......Yet another guy did EXACTLY what you did, bridging something, and blew something else(not sure if it was the CORelay). If you can get someone to turn the key to almost on, not quite engaging the starter, you should be able to put your hand on the CORelay and then KNOW whether it's at least getting juice or not(it will CLICK, fairly noticeably to the touch).

Seems to me if you're bridging things, then finding an issue, I would first check the EFI fuse again(JUST FOR THE HECK OF IT, lol, the 15A fuse in the kick panel) and then in process of elimination, just go through the ONLY few things that can control Fuel Pump Pressure and constant power. A couple of which are the Air Flow Meter Door/Gate(once you know the COR is clicking in the Glove, turn the key to on and then manually open the door in the AFMeter.... IT SHOULD, EVERY TIME, engage the fuel pump.) Another thing is, I BELIEVE, a blown pick up coil and other ignition failures, such as 'NO SPARK'. I'd have to read up on that, but I'd think it would be worth the time.(That is probably not likely as you said it was starting for a second, then dying..... which DOES sound like something is cutting the fuel). And just to be straight, ........Now it wont start, AT ALL, right?

 

It will start but dies as soon as it turns over. It's as if its starting of the fumes or pressure built up in the rail from bridging pump to battery to again make sure I haven't blown the pump. I've checked the fuse and its still good along with the.ignition fuse that also provides power to the other portion of the efi main relay. Also before I replaced this COR the one prior would flutter open and close as u press on the throttle.

 

Just to expound on my last sentence, ...."Now it wont start at all, right?" ...... You CAN'T know that you wont have several tricky troubleshooting issues when you swap everything over, either, right? Not trying to talk you out of anything, just saying, ....and when these things are tuned in, man..... Well, lets' just say I went 170K without EVER doing anything but changing the oil/filter and fuel filter. Ok, ok,....I got tires, but that's besides the point... hahaha.

Sorry, ...just trying to bring you some levity, because there's NO WAY IN HELL this thing can beat you if you run through the process of elimination to the T! ....But, it IS your rig, so if you decide to go back to Carb'd, no one would hate on ya for it! lol.

Best wishes, Irishman!

PS> Just a thought.. but most Dealers will take a look at least for free. Mine, after I spoke with him and showed him how much work I'd tried ran about EVERY test he could to help me find my miss.....FOR FREE! Heck, even at 98$, it would have been worth it to me to stop chasing my tail, haha. It ended up being a poorly ground CAM, which he couldn't justify in putting it on a scope, etc., as the 'BOSSES' would ask questions, lol. But, he did find a couple other things that needed replacing... and I later tested them myself and sure nuff... they were fading, lol. Just a thought, before you scrap all your efforts thus far.

 

Far as what's in yellow... you mean the "COR" would flutter open and closed as you pressed the throttle???? Or the fuel pump would engage and then disengage when you pressed the skinny pedal??

 

PS> You're probably right,...it's only starting because you're manually engaging the fuel pump... But that DOES mean the fuel pump is working, ...that's a good thing to know. Hmmm, so, when you had a new COR in there, BEFORE you jumped anything, and you turned the key on, almost turning the motor over,..... it was engaging the fuel pump on it's own?

 

That's a good idea but I can't see the Toyota guys being to anctious to come diagnose my runner as it pulls up on a trailer Haha. But I could try. I have the 22r head, intake, exhaust manifold, webber carb,aluminum adapter for carb and from what were looking at we should be able to keep same ignition and same fuel pump. Then maybe run a couple new wires and call her good. HOPEFULLY. But that's if this cor fails and I can't get it to mechanic.

 

The cor fluttered open and close. I removed the cap to watch it work. The truck will half ass stay running if u feather the ˟˟˟˟ out of the gas, like press it repeatedly instead of holding it.

 

So, can you try those things, first?

1. Make sure the COR is engaging still(PS> is this a brand new COR? Can't remember, save me the time of looking back?)
2. If COR is working, Pull the AFM from the Air Box, turn the key to START position but not turning over, and then open and close the door inside the AFM(have someone listen for the fuel pump coming on....and MAKE SURE you didn't leave the jump in there, or you'll just confuse yourself, right? lol)

edit, ignore #1 as you answered while I was typing, lol

 

One thing though... When my COR was going bad, it would get HOT AS HELL! Maybe leave the key in "ON" position and see if it's getting REALLY hot? Was your main relay getting hot? Also, take a wiff of the ECU, .....anything get fried in there when you jumped the MAIN EFI relay?

 

Not bran new no. I'm gonna go check these things out now with the afm. ill let u know how it works.

 

I'll check all those ideas. Thanks chef.

 

Another thing, which I have in my FSM somewhere, lol....

We put a new motor in my buddies truck. The fuel pump was brand new and working fine. BUT, we finally had to pull down the intake and hold the injectors in the fuel rail, coil wire disconnected, and turn it over. The injectors were NOT firing. His issue wound up being two things. 1. The dizzy was 180* off, ..his other buddy helping him had pulled it for something and dropped it in on TDC but #4 rotor location instead of #1(I know, not likely your issue, as yours is wanting to start. His would want to as well, and would kinda kick over with ether, but not start or stay running) 2. He pulled back the harness to the pre-horse shoe section and the 1-into-2 wiring connections were completely corroded and had stopped him from getting fuel to fire from the injectors completely....but IT WOULD keep pumping fuel, no problem(all over the place, as a matter of fact! lol)

I believe you can test for the injector pulse fairly easily(I did so, but just can't recollect EVERY detail off hand)...by using a multi-meter at the ECU, testing the No.10 and No.20 Pins. A guy on here was checking out on almost every account, but wound up finding that his "injector resistor" was toast. There is a test for that as well. (Granted, ...this is all only relative if you rule out the 'Fuel Pump Function', i know.)

Edit; I'm not sure on this, but I think the fuel pump engages through the COR and AFM. THEN the pump stays on at full pressure and is limited by the Fuel Pressure Regulator, through vacuum pressure. The voltage to the injectors is limited only by the Injector Resistor, from 12V I believe to 5V. Sorry, just trying to refresh my tired brain, lol.

 

I believe the "Brake" Function is connected to the "Fuel Injector Cut" System, too. Not sure if it can drop the pressure off completely, but that BK pin is also tested in the FSM at the ECU.

 

I know my break booster seal is shot but that will only effect the fuel when I applying brakes. It will leak vacume pressure out of the booster causing the idle to fluctuate. Nice thinking but its not the problem.

 

No, not the 'booster'.

EFI trucks like ours have a function that is made really for Automatics, ...but they include it in manual tran's trucks, too. It's a "Brake/Injector Cut", electronic function. When I mentioned the ECU, it's because the ECU has a PIN for that very function(it's so you can KNOW that the ECU is reading your Brake light.... And think about it, why else would the ECU care if the Brake Light is applied, right? lol) I DOUBT that's anything to do with your issue...just mentioning it for point of reference because IT CAN cause issues with fuel systems.

Think of it like this... When you're doing over 1000 RPM, ....you come to a light, apply the brakes, before you push in the clutch... this function WILL drop you to IDLE level, immediately. I know this because when my idle was sticking up at around 1100, and I'd come to a stop light, my idle would bounce up and down from 1100 to 750rpm, OVER AND OVER, until I took my foot off the brake.

Again, it's not related most likely, but I just wanted to clarify that I'm not talking about the booster. And, also, vacuum pressure is pulled on the booster, but can't return with backpressure to the booster because of the stop valve between the booster and plenum. If that valve goes bad, it CAN blow the booster diaphragm.