How about your gas tank, have you put heat insulation to reduce temperatures since the tank is just inches away from the exhaust. You can check this thread as well: Link
Stalling not just in High, Hot, & Heavy (2 Viewers)
- Thread starter Pskhaat
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I just experienced this shutdown issue again after 5 years and 60k miles without issue. In both cases it happened at above 105ºF (>40ºC) ambient and climbing at <50 mph speed or stopped at intersection. I have an '06 Land Cruiser.
Where is the fuel pump resistor located?
Where is the fuel pump resistor located?
should be on the windsheild side of the airbox, there are 2, one has a black box covering the heat sink(mounted on top of the wheel well), and the other one mounted on the (left fender) next to the other circular box. i recommend cutting the 2 wires that go into it and soldering them together to bypass the sensor.
Does anyone know for a fact that this resistor is the problem? Its less than 1 Ohm. The resistance would have to go up a lot with temperature to completely stop the pump. I doubt that could happen at temps that could occur under the hood without causing an engine compartment fire. So what's really going on?
i was never able to confirm this, tried to make sense of the data heating the resistor with a heat gun and thermocouple here are my results.
the only reason i think it’s the resistor is because as soon as i soldered the wires together it’s been fine since.
2001LC
SILVER Star
The resistor is not likely the problem, but it can be a factor. As I recall, @Calvinswartz first saw issue after blocking fuel resistor with a compresor, than benefit after moving it to cool. But his condition returned, and then seems he had charcoal canister issue. His issues many have been fuel boiling, and fuel pump.
Fuel pump is in the gas tank.
I've replaced many 06-07 fuel pumps, which corrected BK1 & BK2 lean condition result in engine stalling for few minutes. This condition happens, on hot days after running in high RPM. Like when climbing a pass. Then dropping back RPM, which reduces fuel pump speed (multiple speed fuel pump based on RPM). Like when cresting a pass and letting of gas pedal to coast down hill. Same happens when passing on HWY. Fuel pump gets hot and increases resistance. As it drops back to low speed/flow, it fails to develop adequate fuel pressure/flow. New fuel pumps corrects this condition.
This is not only reaseason for stalling, but classic on the 06-07. When passing or climbing a pass in the summer heat.
well said by 2001Lc, however note that the multi speed fuel pump is controlled by 2 circuits. an open mode, which doesn’t use the circuit with the resistor aka your high rpm fuel pump circuit, and a closed mode which switches to put the fuel pump resistor inline, therefore reducing the pump rpm and making your low rpm fuel pump mode.
I’ll see if I can set up to do a test and confirm @Calvinswartz results. We have the right equipment here where I work, I would just have to make sure it is available for my use. After giving it some thought:
13.2V through 0.97 Ohm = 16.61 Amp, increase resistance to 1.6 Ohm and current drops to 8.3 A, which is HALF the nominal current. So if current is what is limiting the fuel pump then it is possible that this is playing a role.
Relocating the resistor to be ahead of the radiator and exposed to ambient airflow would not be difficult.
13.2V through 0.97 Ohm = 16.61 Amp, increase resistance to 1.6 Ohm and current drops to 8.3 A, which is HALF the nominal current. So if current is what is limiting the fuel pump then it is possible that this is playing a role.
Relocating the resistor to be ahead of the radiator and exposed to ambient airflow would not be difficult.
2001LC
SILVER Star
Keep in mind. During high RPM, resistor is bypassed, and full battery/alternator voltage is delivered to pump. It's during low RPM (slower fuel pump speed) current flows through resistor.
I'll add: In the dozen or so 06-07, which had the so called "vapor-lock" (Summer high RPM to lower RPM stall). Replacing fuel pump total corrected.
I'll add: In the dozen or so 06-07, which had the so called "vapor-lock" (Summer high RPM to lower RPM stall). Replacing fuel pump total corrected.
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After reflecting on this, trying to remember when it first happened to me in July 2019: I recall noticing no throttle response and then noticed the RPM go to zero (AT must have automatically gone to neutral). I was in the left lane on I-15. I was able to get over to the right lane and coast to the next exit. So it must have happened as you suggest, going from high RPM high load, to low RPM low load.
The most recent instance about a week ago: First instance was stopping at light after highway exit. I had been driving on I-40 in 107ºF temp. Second was on a country road, same temperature, and again I was able to coast for an extended time, several minutes at least.
So I agree that going high load/RPM to low load is a factor. Thanks for pointing that out!
2001LC
SILVER Star
Is this after driving in high RPM, for at least a few minutes. Like when, passing or ascending a pass. Then engine dies just as you reduce RPMs (take foot off the gas pedal)?
Pskhaat
Tourer
- Thread starter
- #74
There is no rhyme or consistent reason. I can be slowly driving around town. Or towing. Or slowly climbing well above treeline.
Hot weather and high altitude and ethanol fuels seem to be the only consistency. Though I've experienced this low at under 5k feet as well. I've changed fuel pump, wrapped fuel lines and added a 12v cooling fan to the resistor.
I'm convinced it is a fundamental problem with late model EVAP, placed too low in the system, and hastily/not tested by Toyota.
Thanks for posting!
We have a real engineering problem on our hands. There are multiple potential causes and we don’t know which one (or combination of causes) is the root cause. We are going to have to work together to find a solution.
2001LC
SILVER Star
There is an issue with EVAP. Number one is contamination of CC.
So the fuel pump of the 06-07, act similar, but a bit different when bad. The test is on a hot sunny day. Pull up a pass in high RPM, for 5 or 10 minutes. As you crest the pass, let off gas pedal. Engine dies! If hook into tech stream at the time, do not turn off key. Check for DTC first. Either current or pending. We see BK 1 & BK2 lean. test fuel pump (by the book, fuel pressure testing, will not reveal)
Once they start rough idle or stalling, just driving around town on hot day. It almost always the Charcoal Canister (CC) is saturated (contaminated). We see a much higher instance in the 03-up. Which is when the CC was move to the rear. So yes, it is and EVAP issue.
The two worst cases I've seen, where I did check weight of old CC after replacement. One really bad vapor, boiling, rough idle, stalling 2005. CC was 25oz over. A second 2007, was not running as bad, but close. CC was 20oz offer weight. The overweight, is indicative of contamination (saturation with raw fuel in CC)
I can't stress enough. All system must be in proper working order, before replacing CC. Or we risk contaminating again. After which we must ahead to some rules, so we don't flood CC:
- Never add more fuel, after auto shut off of filling station pump handle.
- Maximum of 7/8 or less, tank of gas. When ascending a rocky mount pass.
- Avoid topping tank on hot sunny day. Unless drive about 30 miles as soon as you do, to draw tank down.
We also need to make sure ECT, AT fluid temp & fuel trims are all inline. If not something needs correcting.
If a heavy with under armored, especial bell pan. It can't hurt to do some shield, also.
Pskhaat
Tourer
- Thread starter
- #78
How long does it take the fuel in the charcoal to evap out? Vacuum pump?
I hear you @2001LC about the other systems first, but the prevalence of this from Toyota is embarrassing. (I believe we've shared this conversation before
These systems should be an order of magnitude more resilient than they are, even if there are upstream problems. These are bloody LC, not F150s. Yes, I'm just ranting due to my discontent with this issues.I don't have techstream. What is "BK 1 & BK2 lean"? Lean combustion?
One of my shutdowns happened on flat ground, after highway cruising, coming to a stop after the exit, with less than 1/4 tank remaining.
The second one that day matched your description more closely, but it was not high altitude, and the climb was not that long.
In both cases ambient temp was above 104ºF (40ºC).
I have climbed even the West side of the approach to Eisenhower tunnel under normal temperature conditions (under 86º F) without issue. Power was WAY down due to thin air but no rough running or shutdown.
Can you explain how the CC / EVAP system causes the lean fuel condition?
Easy fix, don't run the truck down below 1/4 tank. The fuel heats up considerably more and it also starts to expose the pump to air which causes it to heat up even more and there is more surface area exposed to the exhaust compared to volume when the tank is low. Heat is our enemy here.
2001LC is a shaman waving his stick and beads around. He blocked me so I can't read what he wrote, but let me guess. It was several paragraphs with poorly written grammar about how you need to just keep your truck stock and measure your engine coolant temperature.
I fixed this problem. You can see my posts in the other thread for how I fixed it. It's done. Solved. Fixed. Banished.
I would link you to my post but 2001LC blocked me so I can't read that other thread any more.
