ChefYota4x4

iTrader: (5)

Not only that, Drew... but by comparing readings AT The AFM, TPS, etc., etc., against the ECU... you can usually pin down a 'WIRING ISSUE', ya feel me?

Best wishes on the hunt!

lovemy1992

I am having almost the same issue I think,
My truck just started to lose engine power and shutting off while I was driving,
I knew it was not battery since all my electronics still work and my batter is not bad,
I can usually restart it but it seems that the amount of time it will run now before shutting off is down to seconds. Now this all happened in like a span of the last three times I have tried to drive it, my father thinks it is a fuel pump but we are not sure exactly how to diagnose it for sure.
The fuse is not bad,
The relay which was easy to check by putting you finger on it when someone turns the key to on(you can both feel and hear a click if it is working) mine was fine,
But when we put our ear to the gas tank to hear if the fuel pump turns on no noise could be heard,
so now I am stuck, how do I make sure it is the fuel pump that is bad?
I don't wanna pay for a new pump and replace my old one without being sure that my fuel pump is for sure the problem.
Any Help would be greatly appreciated.
(I don't know a lot about cars/trucks so I am doing this mostly on what I find off the internet so please feel free to correct me if am wrong on anything here .

ChefYota4x4

iTrader: (5)

Lovemy... You could start here.......

http://www.4crawler.com/4x4/CheapTri...shtml#FuelPump
http://www.4crawler.com/4x4/CheapTri...ORelayLocation

But I'd download an FSM as well, just to run through your year specific troubleshooting procedures/breakdown tree.

Off another site; "Locate the diagnostic check connector in the engine compartment, use a test light or digital meter, check for power at Fp terminal when cranking or if the engine is running. That will tell you if the fuel pump is getting power or not. If the pump is getting power, next crack the fuel fitting for the cold start injector at the plenum, if you get a good spray of fuel, you have fuel pressure. Next disconnect one of the injector connector and connect a test light across the two terminals, if the light blinks while you are cranking, you have injector pulse signal. If that is the case, you have to do a little more testing to determine what is going on."

You can also bypass the pump relay system by jumping, IIRC, "FP and B+" (Let the guys verify that, I'm exhausted, can't remember off hand, lol). THAT is probably the easiest test to do, by simply just opening the diagnostic port next to the fusible link/relay box... The smaller one, just like you would jump TE1 and E2 to set the timing.. You can bypass things so the fuel pump will just switch on)

Start with the pump... No Pump, no GO-GO, right? (Actually best to start with the EFI fuse and COR for 'CLICK'... but you've done that..... Now to see if you HAVE voltage to the pump, ya know?

On your's, being a 92.... It's a MAF, not AFM, right? Anyway, still should work on the test of; Open the Vane/Gate in the AFM while the key is on.... While you do that, have someone listen for the pump... Since you have heard the COR clicking... voltage is being ALLOWED, most likely... but that doesn't complete the circuit, totally. Open that vane and have someone listen/you listen, whatever. The pump SHOULD kick on when you open that flap/vane/gate, k? Just dont' touch the sensor in there, it's VERY sensitive lol.

thedrewski86

Well, haven't been on in awhile but I did get some checking done. I do have spark. It's pretty orange but I definitely have consistent spark. I checked voltage at the Not 10 and No 20 terminals on my ecu per the fsm. They check out to spec (12v).
Next will be checking voltage to one of my injectors. Is it possible for the cold start to get fuel and the regular injectors not to?
I thought the weak spark was odd. I do have NGK iridiums on it which I have since seen downplayed a bit on this site. They do work though so that's not my real problem.
Oh well, onward and forward as I have time to tinker...

ChefYota4x4

iTrader: (5)

Yes, the CSI can fully work while the Injectors are not firing at all. they are on separate circuits. The CSI works off the CSI Time Switch which is reading the coolant temp and then causes the CSI to have 12V or not, according to temp.

thedrewski86

Well, I was able (somehow!) to squeeze my hand in to pull the harnesses off the no 1 and 4 injectors. Hooked up my voltmeter and I'm barely getting 0.17v to them. Obviously there is a communication breakdown between the ecu and the injectors.

Here is what is really odd; it fired! It hasn't done that this whole time but for some reason it stumbled up to 500 rpms for about a second. Oh well, I found a problem, now off to the fsm again...

myyota

Untape the wiring harness for the injectors and follow it back to were there spliced together, its common for the factory connection to corrode and break. If thats the problem solder it back together and that will fix the problem.

ChefYota4x4

iTrader: (5)

YES! Cheers to 'getting closer'!

MYYOTA is correct... There is NO shortage of guys who've had those Y-Connectors for the injector pairs 'snap' on them... ESPECIALLY after a rebuild which is when many people pull the harness up and out of the way, bending that Horseshoe Bends in the Harness straight, etc.

Also, if you read the FSM carefully(FI Section somewhere in there)... It says, "Grab the harness arch and pull up and down on it, looking for stumbling or smoothing out. Do the same with each connector to injector", etc. .... It has diagrams on how to do it properly and how TO TOTALLY AVOID doing it! hahha.... Interesting... Didn't you say you swapped out ECU's as a testing method? (curious)...

Best wishes, Drewski

cman1

iTrader: (1)

been there ...done that!!!!! my 88 pickup wire was black inside and snapped like a twig,cut out the bad section and spliced it,youll have a heck of a time trying to solder the old wires,doesnt work at all.get a good quality splice. good luck!!!!

thedrewski86

Sweet, I'll get to it. I hate wiring especially when it's all tucked neatly into the factory packing and has been undisturbed since 94! Maybe I can get to it after work.

ChefYota4x4

iTrader: (5)

Trust me, Drew...IT'S VERY DISTURBEDDDDDDD! hahaha. WIMean is.... Wait til you open that up... it's NOT OFTEN that those particular wires are all pristine and cherry.. AND, the way, as mentioned, that the factory did that splice? PRONE to corrosion and electrolysis!

Hope you find it soon,..... mine has followed me through 2 motors and 100 hours of chasing my own tail.... I GIVE UP!(shhhhhhh, don't tell it, but I'm actually not going to EVER give up... just want that chance to 'SNEAK UP ON IT AND BFH TO THE HEAD!' ... k? )

thedrewski86

I pulled my wiring harness apart and I found the wiring from my ecu to my injectors. I also found the splice right by the firewall in the engine bay (I guess I didn't need to pull my upper plenum but it made it easier!). I get good continuity before the splice and to my injectors. The splice looks pretty clean too. I'm going to solder them up and shrink wrap them to be safe but is there anything else I can check before I button this up? Honestly they seem fine.

Here are the 4 white wires going to my ecu.



The 4 black wires from the injectors go into a wrapped up bunch of wires and then over the engine. Should I break into all that and check them too? Seems like I'm making a lot of work for myself undoing all this and I haven't found anything that looks corroded. All the wiring looks pretty sound.

thedrewski86

Okay, I think I'd better lay off today before I shoot something. I started following the black wires back and then something hit me. I think I checked the voltage to my injectors wrong. I checked the voltage across the two pins in the injector wiring harness. I just now decided to check between the pin with the white wire and red stripe and grounded to the battery, turned the key to on and all of a sudden I have 12v going to my injector. WTH?! So it seems fine right? I just don't know how to use a voltmeter.

I have no idea what's wrong with this now.

scope103

I'm having a little trouble following what you're doing. The injector harness should only get voltage when the injectors are opening. So to test them, you need to crank the engine. Not just key-on. Is that what you were doing?

My schematics show the Black-Red wire as connected to IGN2, so that with key-on it has 12v all the time. The White-Red wire (for injectors 1,3, and 5) is grounded by the ECM to open the injector.

So, with Key-on you should get 12v at the Black-Red side of the injector connector, "something like" 12v to ground on the White-Red side, but between the two wires (across the injector) you should get a very low voltage (like 0.17). (I say "something like" because you are actually measuring an "open" circuit through the computer.)

With the key to Start, you should get a fluctuating voltage at each injector, so a multimeter won't help. But a "Noid" light would.

Does this help?

thedrewski86

It does help. I checked back a few posts and I said I checked the voltage at my 1 and 4 injectors. I was getting 0.17v like you just said I should. That was from the white wire to the black wire while cranking. I checked yesterday from my white wire to ground and I got 12v.

...and no, I haven't picked up a noid light yet. I hadn't even heard of one until it was mentioned a few posts back. I guess I'll start putting all this back together so I can test stuff while cranking. I removed the upper plenum to get to all this so I guess I should put that back on.

I keep going under the impression this is electrical but I have no idea any more. I have spark at the no 1 spark plug (I guess I'll go ahead and check the others), the door in my vaf opens when I crank so I'm getting air, fuel is being pumped but I guess I'll try the stethoscope to hear if each injector is opening. My hearing sucks so that's gonna be iffy at best. I'll go get a noid light too.

ChefYota4x4

iTrader: (5)

Wow, what a nightmare this can turn into, this hunt, right? ... And you're doing it on the VeeZee, which I KNOW is harder to fish through, Drewski.. Sorry man!

BTW,...that wiring DOES look surprisingly good, compared to SO MANY I've seen on here! lol... (Mine probably included in that test.... I've AVOIDED 'tearing in', so far! hehe).

Scope is a NO NONSENSE, right to the 'FSM POINT' dude! Good to see him on this! Of course.. that makes me realize that I MYSELF could start reading EVERY STEP in some of this.. Rather than getting to a point and 'MEH, I'ma kill something!' hahaha. TOTALLY can relate to that, as well, Drew! Thing is... I have run through the FSM and boards so many times with my gremlins... Maybe I'm starting to develop Munchausen Byproxy in regards to my feelings about them???? hahaha! (Shhhh, ...I'm trying to fool them into complacency with reverse psychology! ).... I'm sure Scope is saying to himself, "Yeah, uhmmmm, that's not gonna work!" lol... Just trying to keep ya from "shooting something", like ya said, Drew

I think you said you got the connectors off at one point without pulling the plenum, etc., right? So.... YES, the noid should work. If you have trouble finding one made JUST FOR THE VEEZEE... Go to O'Reilly, rent the noid light kit and .... I believe I used the Probe EFI one... You have different impedance, so might not work on that choice... I'm sure Scope would know which one would though. Mine all lit up! Then I learned that the injector itself completes the Circuit and plunges open and closed, etc.... Did the FULL connection, with light between the injector connectors and inject's..... and WHICH didn't work? >>> #2! Just wanted to verify why my #2 Header runner was barely getting warm after 30 seconds or so still... Noid verified it was stuck closed. RC Injection(whom serviced them in the first place) verified more for me... They found, with the injector on the bench, that a BLOB of crap had broken free from the hose between the rail and filter... and lodged RIGHT IN #2 upon 'First start/Break in of fully rebuilt motor'... I was testing pins and everything too... But as Scope said, Have to be cranking over to see voltage at the Injectors or (No.) pins at the ECU. Your issue sounds WAY more electrical and as though it's shutting down all the injectors,....not some blob of stuff like my issue. Mine ran... Just on 3cyls, lol. Yours wont even POP, right?????

Feel like your close, Drew! Don't shoot anything! lol... If you do, DON'T SHOOT THE VEEZEE!

thedrewski86

Chef, what the heck is a veezee??

Edit: if you mean 3VZE, no, I don't have that. 22RE all the way and forever.

ChefYota4x4

iTrader: (5)

Ahhh, I follow lots of threads, sorry... When SCOPE said, "injectors 1, 3 and 5" it threw me off... Gotcha.

So then, that Probe Noid Light might work for ya. (I couldn't find much in the way of Import Noids in the Parts stores 'Borrow our Tools' Section behind the counter, ya know? )

thedrewski86

Yeah, that threw me too but I realized he was thinking v6.

I was flippin through this Snap-on tool I have and it has tests for the injectors that check the waveform signature integrity during cranking, wouldn't that be the same as what a noid is telling me or am I missing the point of a noid?

ChefYota4x4

iTrader: (5)

I'll let Scope or someone of more "GURU" status answer all that in a technical way. I just know that when I hooked up the noid to the connector... it lit up like the 4th... When I completed the circuit and included the Injector... it wouldn't light up.

Maybe the Snap On tool DOES measure the injector pulsing in Wave form and you can read it on your tool.. Not sure. I'm sure someone will know. Maybe listing what number snap on tool it is would help?