YotaTech Forums - Starts and dies...... HELP!!!

YotaTech Forums (https://www.yotatech.com/forums/)

- 86-95 Trucks & 4Runners (https://www.yotatech.com/forums/f116/)

- - Starts and dies...... HELP!!! (https://www.yotatech.com/forums/f116/starts-dies-help-296558/)

Starts and dies...... HELP!!!

Ok guys this is a mess not sure what's going on but this is getting bad. I need the 4Runner back up and running ASAP but it's fighting me every steep of the way.

It will start up with no problem and run for about 2-3 seconds and just die almost like the motor is being turned off. As soon as she shuts down you can fire it right back up again and will do the same thing over and over again. Applying throttle doesn't seem to help and turning the distributor doesn't seem to do any thing other then make the RPMs spike higher when it does fire. The motor will jump to about 1500 rpms and then fall from there.

The he only things I can think of our the following.
VFAM randomly crashed out.
Fuel pressure regulated randomly failed
Maybe the remote start box is freaking out from being disconnected.
Who knows what else.

Engine has 150+ psi across all cylinder and new flame thrower injectors. Unplugging the cold start injector doesn't seem to make a diffrence so I assume the injectors are firing at least on start up for a second.

The new motor has rough timing set almost dead center at 10 degrees so I don't think timing is the issue.

Any help or advice would be great. I am searching my tail off and coming up with a lot of possibilities but no clear path.

Update.
1995 4Runner SR5 3VZE 5 speed post engine rebuild.

A problem well-stated is a problem almost solved. What truck-year-model-engine-transmission?

IF 22RE, VAFM or connection to it malfunctioning? To verify, jump the pins of the fuel pump connector (rectangular one hiding in lower right-hand corner here: Attachment 112737

If that fixes the problem, look at VAFM, Circuit-Opening Relay and wiring between then two.

Take a deep breath. Feel better?

What you're describing is the classic sign of a COR-VAF problem, and nothing could be easier to diagnose. Jumper FP to B+ in the diagnostic connector, then try again. If that solves your problem, it means the COR is closing with key to start, but the VAF isn't holding the COR closed once the engine starts. When the COR opens, fuel pump stops, and engine dutifully follows suit.

DON'T just drive around with the jumper in. If you get in an accident that breaks a fuel line, you want that fuel pump to shut off immediately, whether or not you can reach the keys.

Sorry should have been more clear. 1995 3VZE 5 speed.

I have jumped the fuel pump and verified it is pushing fuel but still will not run for more then a few seconds using the FP to B jumper wire. That was the first issue I assumed.

I also pulled the fuel return hose to verify that fuel was flowing out of the return line and it is.

As far as taking a deep breath I have a lot of pressure to get her up and running. It's 1 of our 2 vehicles and we have 3 kids including one with special needs. Our other vehicle is a 2016 sienna van that I have been using every day for work however the wife really needs it for the kids. I am just exhausted from trying to figure this out and wouldn't post unless I had attempted some trouble shooting and searching first.

Need to check for engine codes. Could be something simple that the check engine light will narrow down for you. It's often overlooked but to me it's always the first thing I check

Sorry I have been scattered brained.

Its pulling code 24 and 31

Those two codes both originate in the VAF, so the easiest way to get them together is a bad connection to the VAF. And that bad connection will shut off your fuel pump. Even if the fuel pump is running, without the VAF signal the engine can't run.

I know you tried running it with the jumper, but is it possible the jumper shook loose? Try removing the EFI fuse for about 30 seconds to make sure you clear all stored codes. Check to make sure they're gone. Start the pump with the jumper (verify by sound), start the truck, when it stops running listen to hear if the pump is still running. Then check to see if the codes returned.

Thanks for replying to his codes scope.

Double check all your wires at the plug in at the afm. Could be wires broken or pushed out or even corrosion.

Get a multi meter and book and check the values on the vafm

That's the goal for today. I slap have a supra VAFM sitting on the shelf but I would of course need to make a pipe to support it if the stock VAFM is faulty. I did check all the pins and the connection originally but I will double check the wiring and get the multi meter on her.

I do find it strange that she just died kind of randomly. With the original fuel and vacuum issue we did have a very small back fire I didn't think any thing of it but I guess that could have possibly damaged it internally.

10 4. Keep us updated. I work night shift so it'll later this even8ng before I get back on. Good luck

So I rigged up a temporary intake and hooked my spare 7MGE VAFM to her and she fired up. I will need to build a new intake since the supra VAFM is bigger and will a new air box but at least it's running.

I am concerned about the amount of fuel coming out of the over flow to the fuel pressure regulator. It pushed out about 6 oz of fuel in probably 20 seconds.

Quote:

Originally Posted by cbr600rx7 (Post 52333265)

Was it running when you checked the flow from the regulator or was that with the fuel pump jumpered? It's not going to be returning a lot of fuel when it's running. I haven't ever checked mine this way as I have a good fuel rail pressure tester.

Quote:

Originally Posted by cbr600rx7 (Post 52333265)

I am concerned about the amount of fuel coming out of the over flow to the fuel pressure regulator. It pushed out about 6 oz of fuel in probably 20 seconds.

You should get about 1/2 liter/minute at idle. So you're pretty close to normal.

Quote:

Originally Posted by Charchee (Post 52333271)

... It's not going to be returning a lot of fuel when it's running. I haven't ever checked mine this way as I have a good fuel rail pressure tester.

I'm not sure why you would think that. The FPR sits at the END of the rail, so it sets the rail pressure by "dumping" the flow it doesn't need. By design, the fuel pump has to put out enough flow to cover the maximum possible demand by the injectors, PLUS enough to keep the FPR open. And compared to the design maximum, you're not using that much fuel flow just driving down the road.

Fuel pressure and Fuel flow are two different things. Usually, we care about fuel pressure (as that determines mixture), and only need the flow to be "enough" to reach that pressure. But checking the flow out of the FPR can tell you if your pump is getting weak and is just barely putting out enough to reach the correct pressure. The truck will run, but not for too much longer. Your pressure gauge will only tell you when it's no longer enough to keep the engine running.

The real advantage of checking the flow at the fuel return is that it is easy. Disconnect a low pressure line, drop a hose into a paint mixing cup, and look at your watch. To check pressure you need a gauge and fittings, but more importantly the gauge has to be plumbed into a high-pressure line. You can permanently install a schraeder fitting (I did), which has its own cost. Otherwise, you're disconnecting a high-pressure fitting each time you test. Which means you have to replace at least 2 crush washers each time (you DO replace the crush washers, don't you?)

Quote:

Originally Posted by scope103 (Post 52333280)

You should get about 1/2 liter/minute at idle. So you're pretty close to normal.

I'm not sure why you would think that. The FPR sits at the END of the rail, so it sets the rail pressure by "dumping" the flow it doesn't need. By design, the fuel pump has to put out enough flow to cover the maximum possible demand by the injectors, PLUS enough to keep the FPR open. And compared to the design maximum, you're not using that much fuel flow just driving down the road.

Fuel pressure and Fuel flow are two different things. Usually, we care about fuel pressure (as that determines mixture), and only need the flow to be "enough" to reach that pressure. But checking the flow out of the FPR can tell you if your pump is getting weak and is just barely putting out enough to reach the correct pressure. The truck will run, but not for too much longer. Your pressure gauge will only tell you when it's no longer enough to keep the engine running.

The real advantage of checking the flow at the fuel return is that it is easy. Disconnect a low pressure line, drop a hose into a paint mixing cup, and look at your watch. To check pressure you need a gauge and fittings, but more importantly the gauge has to be plumbed into a high-pressure line. You can permanently install a schraeder fitting (I did), which has its own cost. Otherwise, you're disconnecting a high-pressure fitting each time you test. Which means you have to replace at least 2 crush washers each time (you DO replace the crush washers, don't you?)

We're on the same page. What I meant by "not a lot of return" is that 1/2 liter per minute idle range. I ought to know better than to use terms like a lot and not a lot when discussing a flow or pressure test. My bad. I use the gauge on the rail to diagnose low flow by looking for a drop in pressure as demand is increased on the engine. I did install a schraeder valve in my rail because I had access to one as well as a quality test gauge set. The only thing I have against the return flow test is that a weak regulator can lead you to believe that your rail pressure is good when it isn't and can lead some folks to rule low rail pressure out as their problem. A rail pressure test will show you which end of the fuel circuit to search next or allow you to rule it out with a greater degree of certainty.

Glad to see you got the vafm figured out as the problem cbr

She is getting there any way. Definitely needs some fine tunning.