Bills86e

She starts up and quits. Re-try--same. Please help.

Bills86e

Well, On my way to Pull-a-Part


Tools: phillips #2 and deep 10mm socket.


In the first you can see the circuit for starting and running the fuel pump. When you first turn on the switch, power goes to the , also -> starter Relay --> prmary coil --> to ground.

It also goes from EFI contact to --> DLC b+, -and to -> the Circuit opening Relay holding coil and through the contacts to the Fuel pump. With no air flow the circuit to the Circuit Opening Relay coil is open, and it will not activate the relay because the air flow switch is not made up..

When you turn on the switch, you power up the circuit Opening relay through the primary coil. This pulls in the closing the contact passing B+ directly to the fuel pump. (1)

On running, the engine will close the fuel pump switch in the volumn airflow completing the circuit to continue holding in the Circuit Opening relay .

HOWEVER if the circult Opening relay primary coil is weak or bad, it will not pull in the relay, so wouldn't pass on any current to the fuel pump, hence it will not start in the cranking position, But if the vehicle is pulled at idle speed, the Fuel Pump switch in the Air flow sytem will make up the secondary pull in coil closing the contacts completing the and the engine will continue running.

When first stopped, it will start again because fuel is still in the sytem under pressure and so doesn't need the fuel pump, but as the pressure falls, the engine will gradually slow, then stop, and not start any more, unless towed at starting speed closing the switchi the air Flow circuit. .


I found the COR on the "A" pillar, on passenger side, after I removed the glove box & panel. The back side of the plug wire connector faceing me.
The relay is bolted there! Hope replaceing it helps.


Under rear passenger seat carpet I found the FP E-plug floor cover.
The FP was more to forward and toward center, so I set my metal
cutter 1/4" deep and luckily centered a 7"x7" opening.
made a bigger size sheet metal cover, 1/2" x #6 self tapping to secure.

scope103

Whoa, whoa!

Before you buy a new COR, test the system. It's almost the easiest test you can do on a 4runner! [but you are correct; the COR is the direction you should be looking]

With key-on, not running, jumper FP to B+ on the diagnostic connector. If it's quiet enough, you should be able to hear the fuel pump run. Now start it; if the engine stays running, you've correctly identified the problem is in the VAF-COR circuit. (Don't leave the jumper in and drive around; if an accident breaks a fuel line, you want the fuel pump to shut off RIGHT NOW.)

Next, pull the jumper, and with key-on, stick your finger into the VAF and push the air vane open. The fuel pump should start, and stop when you let go of the vane. If not, suspect the VAF, but it could still be the COR. (The COR has two windings; one of yours works because it works with the key to STArt, but if the VAF-side winding is open the vane won't close the COR.)

New COR? Not yet! Test it first: http://web.archive.org/web/201003261...96circuito.pdf You don't want to waste time with a replacement part if the existing one tests 'good.'

Bills86e

I put a clear line on the FP fuel return into a catch can. Just after the engine quits, the fuel flow stops. While running the flow is strong. I got a COR at my pull-a-part yard, but have the same results every time. What else can I check that can cause dying? Get up to a minute.
I also just put a new FP on the tank module, just to rule that out. Same result. At my wits confusion.


Scope103 Thank you Can you help more?

scope103

Good test of fuel pressure; now you know your fuel pump is actually stopping. But why?

No.
(at least not until you do the three things I suggested.]

Bills86e

Why....When is answer. If pump stopped, the engine would die.
Now I know engine dies, Then pump stops.


did the three. Would a vacuum line fail make it quit? Map or MaF ??
I don't know much about mechanic-ing the Toy, or where these things are.

Charchee

How long is it running before it dies? Can you rev the engine while it is running? Have you put a fuel pressure gauge on it? You could have an obstruction in the fuel plumbing that is restricting the flow of fuel. Something like a plugged fuel filter or a crimped metal line. Even with a restriction you could build good pressure before you start it but when the engine starts consuming that fuel "without adequate flow" you will see your pressure fall out and the engine will die. The next time the pump starts up, your pressure will return momentarily, allowing the engine to start but only run for a second.

Bills86e

a minute or so. Yes, it will rev. Finger over return line shows powerful fuel spray.
No pressure drop until engine is dead.

Charchee

Lets get the fuel system ruled out of the equation. You said you did the tests that Scope advised. What was the result when you stated the truck with the fuel pump jumper wire installed? Did you leave the jumper on the whole time. It won't hurt anything. Just take it off when you're finished fooling with it. If the truck died while performing this test, you should still have fuel pressure even after the engine stops with the jumper installed. You will hear the pump running and the fuel will be returning to the tank. If it dies and the pump is still running, you can rule out the pump.

Next in the fuel system would be the fuel pressure regulator. It's on the front driver's side of the engine, threaded in to the fuel rail. You said you checked the fuel flow at the return side and had good pressure. That's fine and all but that fuel is always going to be there while the pump is running, whether or not any fuel pressure is actually in the rails. I would hook up a fuel pressure tester to the D-side fuel rail. This will give you an accurate reading of the fuel pressure that is actually available to the engine. I got mine from advance auto parts pretty cheap and it had what I needed to test a Toyota engine which is a banjo fitting. Let me know if you have questions as to where to hook it up and I'll take you some pictures. Below are the readings for my 3VZE:

Fuel Pump Jumper On, Key On, Engine not running. 46psi.
Cranking the engine. 40psi.
Engine Idling 43psi.
Engine off, jumper off, fuel pump not running. 40psi.
Engine off after five minutes. 35psi.

What you are checking here is really the regulator. If it is allowing the fuel to bypass back to the tank at say 20psi, your engine is going to starve for fuel, die slowly and the fuel pump will stop "jumper off" as you described. What you are looking for is low fuel pressure in the rail or pressure that drops quickly after the engine is shut off. Mine only drops about 5 psi and then will hold that pressure for hours after turning it off which is what is supposed to do. A drop of 10 or 15 psi would probably indicate that your pressure regulator is failing. Also check the vacuum line on the regulator for cracks or restrictions in it.

If it passes those tests, I'd say to move on to the ignition system. Your coil or igniter may be overheating after a few minutes of running and causing your problem. There are test procedures for checking the ignition system in the FSM along with all of the specs for the fuel system.

These issues can be a little tricky to find but you'll get it. Nothing just too complicated about these engines that you won't be able to troubleshoot at home. Start with the easy tests, record your results, and just move through the system til you get it. Keep me posted and let me know if I can do anything to help.

Bills86e

Can't find a Toyota banjo yet. Also to rule out the pump, With key on I jumpered the B+ & FP in the diagnostic box, but same results.
Removed Distributor cap and polished off some corrosion on the pins, same agan. No vac lines are cracked or broken.
She will run about a minute, tops. Slowly putters out. Opened the air canister - pushed vane, same. This has me stumped.
Yes, I'd like the picture in case I can find a banjo. Pic of PR also please.

Charchee

I'm leaning toward the pressure regulator being your trouble. If you have a good local salvage yard, you might just pick up one and try it. It's not hard to get to. I'll get you a picture and specs on that banjo adapter this evening. Mine came with my tester I got at advance. The adapters are hard to find. If it comes down to it, I'll mail you mine to use and you can mail it back.

millball

Here's a banjo fitting that I believe will work.

http://www.ebay.com/itm/251254996574?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Charchee

Thinking about the regulator a little more. The way that thing works, even if it were to be failing, I would think your engine should be able to idle indefinitely. It would be when you increase the RPM that it would bog down or die. The fuel pressure test will tell you what you need to know but in the mean time, inspect all of your fuel lines and change your fuel filter if you have not done that already.

One more question. How soon can you get it to crank again after it dies? Do you have to wait a while or will it start right back up? An overheated coil can cause similar symptoms but usually when that happens you have to wait til it cools back down before it will start again.

Bills86e

Today I tried the OBD1 trick, but no codes. Now it does not start.

Charchee

I kind of thought that was going to end up happening. I had the same thing going on a couple weeks ago but mine slowly died one day and then never tried to start again. Here's what I did and you'll probably want to do too.

Double check that fuel pump is still working using the jumper.

Check for spark. I just hooked a timing light to each wire and cranked it over to see that signal was going down the wires. There is probably a better way to do this but I didn't have anyone to crank the truck for me while I tested things.

If you have both of these, I would look to your EFI circuit. There is a fuse for it in the cab. 15A I believe. Check to make sure it is ok. There are a lot of other components of this circuit that could be bad not to mention a bad ground some where. You have the MAF, Coolant temp sensor, Throttle position sensor and several others that all affect the fuel injection of this engine. I may need to be corrected on this but I think most of these sensors will allow the engine to run, at least poorly, if they are faulty and most of them will give fault codes if they fail. So check for codes. If the issue turns out to be the ECM, I don't know if you will ever see the CEL as it is controlled by the ECM. Check that fuse first.

From here out I can't help you too much from my own experience. I have a room full of parts from a parts truck I stripped down a couple years ago. It may not have been the smartest thing to do but I went straight for my spare engine ECM. Plugged it in and it was all better. I'm a little scared I might ruin this one too because I didn't find the root cause of the first one's failure but all good so far.

Bills86e

SOLVED!!!! Thanks and a tip of the hat to CHARCHEE. The Great Diagnosterer.


Got back on it this am after a night of mental possabilities.
Got out the Timing light and everything went all good.
Next I removed the PF cover again and used the clear line trick. NOTHING was flowing! Tested incoming power - All GOOD! WTF
Removed the pump module again to bench test again. Then I found it.
The positive wire into the connector. (checking with voltmeter)
So I cut the wire at pump connector and found corrosion, about 5/8" worth.
Cut that away and used a tube crimp connector, and wiggling the wire was
now not intermittant! I did not notice that when installing the new pump.
Old pump is good too. My guess is the bad wire would fail once carrying amps.


Thank you again CHARCHEE for your Knowledge & Courage & Great willingness
to stay in this with me! YEAAAAAAAAAAAAAAAAAAAAA-CharChee

Charchee

That's what I'm talking about! I was dead set on the fuel supply but the working pump kind of had me thrown off. So it was the old broke, or corroded in this case, wire failure. Only a skilled and patient troubleshooter catches those. All the credit to you my friend.

The factory service manuals for these trucks is several hundred pages long but is missing one page. The first page in the manual should read, "Your engine will not run without supplied fuel, intake air and spark at the plugs. Determine which one you do not have and move along to that section of the manual." It's easy to get carried away with possible scenarios and preconceived ideas but the key to troubleshooting is not to find what is wrong but what is right and rule those things out.

Hit me up anytime you need any help. I enjoyed it.

Jorge3vze

One more question. How soon can you get it to crank again after it dies? Do you have to wait a while or will it start right back up? An overheated coil can cause similar symptoms but usually when that happens you have to wait til it cools back down before it will start again.[/QUOTE]

This is happening to my 1993 3vze how can I solve this problem

scope103

Welcome to YotaTech.

There were a number of tests described in this thread. Run them, report the results. That is how you can solve "this" problem.