Truck stalls when engine hot (after 15 min of driving 45+mph) and then slowing down or idling at stop sign

Tiny
HADIA
  • MEMBER

Sorry for late reply.
I finally bought me a Fuel Pressure gauge with correct Banjo fitting and tested the pressure with the following results:

Switch to ON
Measured 46 psi (Spec: 38 44 psi)

With vacuum hose from pressure regulator disconnected and plugged, engine started:
Measured 46 psi (Spec: 38 44 psi)
Note: Keeping the vacuum hose plugged or not plugged did not make a change in readings!

Vacuum hose reconnected and engine idling:
Measured 39 psi (Spec: 33 37 psi)

Engine stopped:
Dropped to 21 psi and within a couple of seconds drops to about 5 psi. (Spec says that it should remain at 21 psi for 5 minutes after the engine is stopped)

Firstly, these readings are on the high end of the spec (and slightly more).
Secondly, after the engine is stopped it does not hold the 21 psi for long.

Question: Since the reading are high, does it mean the fuel pump and fuel filter are in
working properly as they should?

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Monday, March 26th, 2012 AT 7:03 PM
Tiny
RIVERMIKERAT
  • MEMBER

It sounds like the filter and pump are working. But, it sounds like the check valve in the pump has failed.

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Tuesday, March 27th, 2012 AT 6:12 AM
Tiny
HADIA
  • MEMBER

Thank you. Before I mess with the check valve, theoretically, would check valve failure create the condition that would make the 4 Runner stall while idling at stop light, or is this just another issue with my 4 Runner?

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Tuesday, March 27th, 2012 AT 3:32 PM
Tiny
RIVERMIKERAT
  • MEMBER

It depends on the type of failure with the check valve. It could be experiencing an intermittent failure where it isn't allowing enough pressure to the injectors occasionally, and not holding pressure properly.

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Tuesday, March 27th, 2012 AT 9:37 PM
Tiny
HADIA
  • MEMBER

Thank you again. I assume the check valve is part of the pump and therefore per your diagnosis, the pump needs to be replaced. I will look into this. So far, $846 and going up.
Though I have checked all I could for vacuum leak, I wish I could find an easy and inexpensive way to smoke test the car for leaks before anything else. If I was to do a smoke test for leaks, where would be the best point of smoke entry. Someone suggested the brake booster vacuum hose. Is this an ideal point of smoke entry?

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Wednesday, March 28th, 2012 AT 12:31 AM
Tiny
RIVERMIKERAT
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Yes. It's the one most often used.

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Wednesday, March 28th, 2012 AT 2:13 AM
Tiny
RIVERMIKERAT
  • MEMBER

You may be able to use carb and choke or brake cleaner to check for vacuum leaks, also.

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Wednesday, March 28th, 2012 AT 2:14 AM
Tiny
HADIA
  • MEMBER

Sorry for long intervals between reply. I work on the truck whenever I get a chance and today I smoke tested the vacuum lines using my homemade smoke machine (A 12v air pump, a pickle jar, a few fittings and pieces of tubes and some mosquito repellent coil). The only thing I had to buy was the repellent. Sealed the air filter and introduced the smoke through the brake booster vacuum hose. The only smoke I witnessed was from under the cap of the EGR Vacuum Modulator and from around the Mass Airflow Sensor. Inside the Modulator cap there is a small filter and still in place. Is it possible or expected that because the engine is not running and the EGR Vacuum is inactive therefore the smoke backs up in the Modulator and leaks out? Any comments or suggestions?
Note: I tried to take a few pics but unfortunately, the smoke was not visible in the photos.

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Monday, April 9th, 2012 AT 10:43 PM
Tiny
RIVERMIKERAT
  • MEMBER

An you apply vacuum to it to test it?

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Tuesday, April 10th, 2012 AT 3:10 AM
Tiny
HADIA
  • MEMBER

No vacuum applied. With engine not running but ignition on ON so that I can run the pump, I pumped smoke into the system to find any leaks. Smoke appeared from under the cap of the EGR Vacuum Modulator and from around the Mass Airflow Sensor.

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Tuesday, April 10th, 2012 AT 6:44 AM
Tiny
HADIA
  • MEMBER

Just an update. I reached my limit of spending ($1K) on the truck for now. The truck has officially been put in hibernation. Someday I will tow it to the dealership. In the meantime, I feel like a disabled person who has lost his wheelchair.

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Monday, May 21st, 2012 AT 5:05 PM
Tiny
RIVERMIKERAT
  • MEMBER

I don't think smoke should have been visible. You might try seeing if the seals or gaskets around those 2 parts can be worked on and fixed.

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Monday, May 21st, 2012 AT 10:23 PM
Tiny
HADIA
  • MEMBER

Out of hibernation and back on the road again!
As you all recall, my truck would always stall while idling at stop signs and stop lights.
Running out of options, I played around with Throttle control sensor to see if it would effect idle performance and hopefully stop the stall problem. This action recorded two engine faults.
A) Throttle Control Sensor Fault,
B) Engine Coolant Temperature Sensor Fault.

Set back Throttle sensor to original state and the error for this sensor went away but from here on, the Coolant temp sensor fault persistently remained. I replaced the Engine Coolant Temperature Sensor (ECT) and Halleluiah! I have driven it for 100 miles since and no stall and it passed California s strict smog test beautifully. After spending $1300 replacing and or cleaning many parts, a $13 sensor fixed the problem. For 8 months that I was dealing with stall problem, the truck neither generated an engine fault nor the temperature gauge indicated anything other than the normal driving temp until I messed with Throttle control sensor. How and Why? Well, at this point I don t care.
In any case, thanks to all those who made suggestions and recommendations.

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Saturday, September 8th, 2012 AT 7:27 PM
Tiny
RIVERMIKERAT
  • MEMBER

Hadia, congrats. California's smog laws are the strictest in the country.

As to why the ECT would be bad but not generate any spurious or incorrect readings or any codes, that's one of those things that Toyota isn't telling anyone.

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Sunday, September 9th, 2012 AT 1:13 AM
Tiny
MSMITH4466
  • MEMBER

My truck does the same thing when all warmed up it also bucks and gas gage goes to e I have changed every censor there is and still does it

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Wednesday, September 9th, 2015 AT 5:54 PM
Tiny
HADIA
  • MEMBER

If the gas gauge goes to E, I would take a closer look at the Fuel system. Have you replaced the Fuel filter?
(on the side: My truck is in hibernation again. After more than a year of driving smoothly, The fuel dampener is leaking gas. It is a less than $200 part but unfortunately it is cramped on the back of the engine, impossible to get to)

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Thursday, September 10th, 2015 AT 12:25 PM
Tiny
MMMDAVE
  • MEMBER

I had to replace my leaky fuel dampener recently. Yes, it's a pain to get to. Best thing is to remove plenum. While I was in there, I replaced pcv valve. Ironically, that fixed the "stalling when hot" problem, which is why I subscribed to this thread in the first place?

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Thursday, September 10th, 2015 AT 1:03 PM
Tiny
HADIA
  • MEMBER

Thank you Mmmdave. Up to now I had not come across anyone who had to replaced the Fuel Dampener. I am not sure of your 4R but My Toyota 4R in 1990 model (3VZ-E engine). Firstly, I am short on vocabulary! By Plenum I assume you are referring to the air intake chamber. Because of the age of the car, and the fact that there are so many components hat have to be disassembled for this job, I have hesitated to start on this. I am scare of that one bolt or a nut that just may refuse to open or get damaged trying to open.
In any case, if you (or anybody else) can provide information on special tools if needed and the proper steps I have to take to replace the dampener I very very very much appreciate it.

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Thursday, September 10th, 2015 AT 2:10 PM
Tiny
MMMDAVE
  • MEMBER

Mine is also a 1990 3vze. Lots of vacuum hoses. Get a roll of masking tape and a sharpie and label everything. Take pictures. All so you can put it back together right :-)

Get get a new plenum gasket, and a pcv valve before you start. You'll have to disassemble fuel lines and throttle linkage too. I'd advise doing it in a well ventilated space. Those gas fumes will get to you big time. I didn't use special tools, just a good set of socket wrenches mostly. The usual.

There may be a YouTube video out there that would be worth 10,000 words.

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Thursday, September 10th, 2015 AT 2:21 PM
Tiny
MMMDAVE
  • MEMBER

Oh yeah, the plenum is the big silver thing that covers the top of the engine.

Good luck!

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Thursday, September 10th, 2015 AT 2:30 PM

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