Air In Fuel Line

But still no codes, weird.

Further reading indicates that Toyotas may not throw a code until above +/- 30%.

 

About 60*F. It had sat overnight for the first test, maybe 30 minutes after shutdown from that test, for the second.
Nope, nowhere near a heat source, I didn't even fart in the driver's seat.

 

And...

Any other parameters that I should be looking at?

 

First, the fuel pump is a sealed unit and it cannot be disassembled or fixed. Only replaced.

The Red Underlined parts above indicate a leak somewhere probably an injector or two.

Measure the fuel pressure.
Standard:
281 to 287 kPa (2.87 to 2.93 kgf/cm2, 40.8 to 41.7 psi)

• If the fuel pressure is greater than the standard value, replace the fuel pump.
• If the fuel pressure is less than the standard value, check the connection between the fuel hose and fuel pump.

Turn off Fuel Pump.
(p) Check that the fuel pressure does not change for 5 minutes.
Standard:
147 kPa (1.5 kgf/cm2, 21 psi)
If the result is not as specified, check the fuel pump and fuel injectors.

 

Okay, I wasn't sure if it really only needed to hold for five minutes or should hold almost indefinitely. The FSM only mentioned the five minute mark. And, my drop after five minutes, seemed maybe only on the borderline.

Any recommendations on injector brands?

 

Go for a drive and see if the trims move toward zero at all.

Can you get some 02 voltages up on the screen while driving?

 

Already ahead of you on the O2 voltages. Tomorrow, I'll give it a ride around and see what happens. Messing around with it in the driveway, no, no changes. I held RPM's at 2500 for about 30 seconds, nada.

Right now, it seems like it's coming down to O2 sensors and/or injectors.

 

A coolant temp sensor reading would be helpful too. That's the first piece of info the pcm looks at when the truck is first started. Oftentimes when those temp sensors fuck up they report way too cold, like neg 140 degs. That'll flood the system with too much fuel.

Its definately over-fueling.

Given the lurch when it goes into CL I agree with nd4, suspect a bad 02 sensor

 

I have the ECT (and IAT) up on my app all of the time. It has always seemed normal. This summer, through the mountains, my temp got up to about 200* with 75* ambient, towing the 3500# trailer. This past trip, when the problem started, it never got over 195* with about 65* ambient.

Side note-
Funny thing, after my temps climbed this summer, I noticed that my stock Toyota aluminum skid was blocking clean air from going through my lower grille area. I took it off for now.

 

Curious to see what it reads from a cold start, on up until closed loop takes over

Also be careful not to confuse ambient (IAT - outside air) with coolant temp (ECT)

 

OBD standards are that +10 -10% causes a code. It just takes a specific drive cycle and your scanner may be disrupting that.

That's over rich, I'd be looking at temps, pressures, MAF, pressure regulator, etc.

One hail mary I've seen work on a tundra was a dirty gummed up throttle body caused a rich condition. It doesn't hurt and theres loads of write ups to clean the throttle body and MAF sensors.

I don't think its an injector as both banks are rich.

 

@dbbd1 did I miss where you stated the year model of your truck?

 

The truck is an '07 with 65k miles on the clock.
I'm the original owner.
New plugs at around 50k, just changed them again, back to denso from ngk, when this started.
New MAF (parts store brand)
Changed air filter, clean intake tube, TB is already spotless.
I did change the oil a bit before this happened. I'm going to pull off the crank sensor and check for oil drippage around the electrical connections.

Both banks doing this is very curious. Both O2 (or all four) sensors bad? Multiple injectors bad?

I usually try to keep an eye on temps, especially when towing. They always start at around ambient and climb normally.

Also, the stumble going into closed loop. It is just that, a stumble, then it smooths out again.

And, let's not forget that damn air that was in the fuel line. Honest, I swear it was there.

And the thought- what if there are multiple problems? Without throwing a code, who knows how long the trims were off. Only once it started stumbling/cutting-out, did I notice a problem. O2 sensors and/or multiple leaking injectors and/or fuel regulator?

And, my original thinking with the fuel pump was this- according to pics, there are two flex lines from the pump (sitting on the bottom of the tank) to the top of the pump assembly. That is where I thought that air might be getting in, less likely a cracked pump housing. Just letting you know where I was coming from with that. My adult life has been repairing hydraulics and pneumatics.

Again, I'll get it out for a spin today and report back on temps, O2 voltages and such.

 

I bet is it fuel pump or filter related.

 

Out of curiosity, do you regularly by gas at the same place? Did you use the same place before this started? Have you filled the tank since this began? When/if you opened the tank cap was it pressurized? Ethanol blend or straight gasoline?

 

The saving grace, if there is one, is that this is becoming reproducible. I was afraid that every time I wanted to test things out, I was going to have to drive at least two hours, towing a trailer. Not where you want to be if it finally quits on you.

Gas- Yes, usually among a few "regular" places. On the way home from camping most recently, no. I do get top tier or, at least, a branded gas station.

I filled the tank approx 50 miles before the camping trip and again for the return trip home.

In Oregon, it's not self-serve. I did not notice if there was or was not pressure.

And it's a year-round blend of ethanol.

 

Check for over pressure in the afternoon and after driving. Is the blend different during winter and summer? Did they recently switch blends? Can you get straight gas?

 

Just took it for a quick 10 mile jaunt.
I did a battery disconnect/reset too.
Ambient was 56 when I started.
Here are my readings...
At startup





About 5 minutes of idling.




After its warmed up.





I guess that I need to start looking at my O2 sensors? Why are both number one sensors reading zippo.

Thanks again!

 

B1S1 and B2S1 do not read O2 catalyzation. They read air/fuel mixtures.

 

Oh!
Um, okay, thanks.
Another day, another lesson learned.

So, then on to the fuel pump? It just arrived today. It's a DW. I read about sometimes a premature failure of the internal check valve so an external one is sometimes added. That should be here soon too. But, I can do that later, since it's external of the tank.