Picked up a '94 4 runner 3VZ-E. Pervious owner said "One day it just didn't start anymore". Spent many hours swapping parts and could really use some help!

When I turn it over, it will "fire" for about 1 second. Spraying carb cleaner in the intake makes it fire faster and run longer (maybe 2-3 seconds).

Fuel sending unit was froze so I dropped the tank. It was rusty inside, so I replaced tank, FSU, pump, and fuel filter. I also blew all the lines out to get rid of old gas. Same result when tried to start.
I tested spark and replaced the 5 plugs I could get to. Same result. (They were pretty black and DRY.)
I poured gas on rag and shoved it in the intake. The engine fired up and ran for about 30 seconds...sounded perfect!
SO....I know it is a fuel problem at that point.

I loosened banjo bolt at rail to blow lines, so I know I have fuel getting there.
I jumped the fuel pump in the diagnosis ports and tried to start with pump running...same no-start result.
I took the larger hose off the fuel injector pressure regulator and operated the pump....fuel squirted out, so I know there is fuel there.

QUESTION:
Is it possible fuel pressure regulator failed in such a way that I have no pressure at injectors? (All fuel just returns to tank?). I have one on hold, but it is $100.
What else could cause the case that I have fuel at rail & regulator, but not going in cylinders?
Advice on what to do next?

Side Note:
In the middle of all this...a dang squirrel got in under the hood and made a nest over by the windshield washer lines last night. He also chewed through the vacuum lines that go to those two electric "valves" screwed to the passenger side under the hood. I haven't figured out how to reconnect those yet since I can't figure out where they go. I know I need to fix that asap, but I assume that isn't causing my "no start" issue since behavior is exactly the same even with those chewed through...and it runs with a gas-soaked rag in the intake.

Thanks for reading...thanks for advice.

 

That return hose off the regulator, clamp it off and try starting it. This will max out your fuel pump but will tell you it's not the regulator, you can run it long enough to verify the COR/VAFM and fuel pump aren't an issue if it does start but.. I think you've already verified that and either your injectors aren't firing or they are full of gelatinized fuel or other nasty.

You can also measure the output volume of the return hose, if the regulator is ˟˟˟˟ I expect you'll get more than the 500ml/min or way less. In which case you want to check the actual fuel pressure on a gauge.

 

Oh
PS fuel soaked rag is pretty ballsy, much safer to just hold the nozzle of the starting fluid open while someone turns the key. Little neighbor kids make good key turners in a pinch.

 

Thanks for the reply. I went and did that and it still didn't run. Do you think ALL the injectors could really being clogged, or is it more likely there is some other issue? For example, whatever makes them "fire" isn't working? Once I made it run with the gas soaked rag (and rev'd up the engine) I would hope that the injectors would clear "enough" to at least "run rough"? Especially since it ran fine..and then just wouldn't start one day?

 

Check for battery voltage at the ECU through the injectors. You can do this with a multimeter or test lamp.

Then check for ground pulses by the ECU on the injector pin. You need a test lamp for this, an LED one because a light bulb won't respond fast enough.

That's #10 and #20, 2nd from the left (top and bottom)


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This isn't the newbie forum but I'm bored waiting for dinner to come out of the oven so you get details, whoohoo
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So you have to remove the right hand kick panel, that's a Philips to lift the front of the door jam plate. And a 10mm or Philips if there is a fastener on the kick panel it's self (yeah I dunno, I never bother to put these back if I have to go in there)

Then a couple more brass colored 10mm hold the ECU to the cab.

Now you can get access to the wires going into the ECU.

Turn the ignition to the run position.

Put one of the brass bolts back in the side of the cab, it's going to be your ground point, clip you test light to it or another hand shiney bit of metal. Now test your ground is good (slide the probe end of test lamp into the back side of the wire going into the top right of the ECU and touch the metal clamped to the wire, this is called back probing a connector) you should get the test light to light up. If it doesn't light either your ground isn't secure or your ECU is upside down, try the bottom left wire or a new ground point and repeat until you get light. (If it's upside down flip it over, another good ground point is the top left wire to the ECU but you might need a small screwdriver or something to make the contact)

So now check the injector wires, second from the left both the top and bottom wires. The test lamp should light up.

You've verified the injectors have power.

Now we check for injector pulses from the ECU!

You can try turning the key to run but might not be able to notice the test light go dim.

Much better is to reverse the probe so the clip end attaches to the injector wire and the probe end attaches to the battery wire (top right). Now when the key is turned to start the lamp will light up (dimmly) instead of dimming.

You need to be very certain about these tests. Perform them several times until you are willing to wager life and limb on the result interpretation..

...
If you have power through the injectors and injectors pulses, they are plugged and the intake needs to come off the engine to get access to them. (Assuming good fuel pressure and volume!)

If you have power but no injector pulses, and have ignition sparks (on a 3vze, wait you did say it was the V6/3vze didn't you *shrug*) you've got an ECU issue.

 

Thank you so much. This is perfect. I'll do this and figure out where to head next...I appreciate your time. I'd buy you the beer/whiskey while you wait for dinner...

 

BTW, those vacuum lines on the passenger fender go to the ADD (automatic differential disconnect) on the front differential. You are correct that they will not directly cause a major starting issue, but if you don't plug them there'll be a vacuum leak that will mess up the mixture.

You'll need to repair those lines for the 4wd to work properly.

 

I just wanted to followup and say "thanks" again. I performed these tests, and I have both power and pulsing. I know I have spark since the engine runs fine if I stuff a gas-soaked cloth in the intake. Now it is narrowed down to fuel pressure or injectors. I'm going to replace the fuel pressure regulator first (the old tank and pump had rust in it, so maybe it failed). If that doesn't work, I'll go tackle all the injectors. Too bad its 'old school' and doesn't have a Schrader valve to check pressure easily...

 

Old dog? New tricks?

Just get an Actron CP7838 https://www.ebay.com/p/1000379201 It has the correct fitting for the banjo bolt. Put the adapter in and leave it.

I would re-check your COR-VAF test: replace the fuel return line from the FPR with 6mm (1/4") vinyl tube to a suitable container. Jumper FP to B+ on the diagnostic connector. I get about 1/2 liter/min out the fuel return. ("Runs for a few seconds" is the classic sign of a VAF-COR problem. The test is to try to start it with the jumper, but you say you've done that.)

Next up is the injectors. That's tougher, but CO_94_PU gave you the method to check for injector pulses. WIth the injectors out they are not difficult to (crudely) test, but getting to them to remove them is a real chore.

 

This is great feedback. Thanks!! I ordered and will do both your tests. If pressure and volume are good...I guess its time to tackle injectors. I see cheap, generic, 6 packs on amazon for under $100. Maybe I grab one of those to swap, and then see about getting old ones cleaned out.