Already have a problem with the Sequoia I just bought.....

[J1000]

Sounds like it needs a fuel pump.

 

[AlpineAccess]

Anodes on what? The battery?

Spark plugs

 

[rushthezeppelin]

Sounds like it needs a fuel pump.

Any further diagnostics I should do on that front? I haven't heard any whining noses coming from that area but I can check closer to it.

 

[rushthezeppelin]

Well swapped 2,3,4,7 with the other coils made it about a mile and stalled again. No codes this time (only seems to throw codes 2/5s of the time roughly). I'm really thinking it's not spark and leaning towards fuel.

 

[rushthezeppelin]

Fuel filter looks pretty new

I did take a look at the injectors, they are blue of that means anything. I noticed that the topmost seals that you can see on the manifold are pretty visible crumbly. I wonder if it's ultimately down to injector seals.

 

[rushthezeppelin]

Or possibly the injectors themselves, I would be surprised if the are original. Given the condition of those seals.

 

[AlpineAccess]

I'm with Jimmy, this reads like a fuel pump. Starts intermittently, doesn't supply enough fuel at higher RPM, lean condition possibly present, etc.

 

[rushthezeppelin]

I'm with Jimmy, this reads like a fuel pump. Starts intermittently, doesn't supply enough fuel at higher RPM, lean condition possibly present, etc.

Weird part is I smell fuel on cold start from exhaust so she's rich on start up.

 

[rushthezeppelin]

Yeah I'm now on the fuel pump train. Just drive home from my parish, got her up to temp in the driveway and gave her gas. Fluttering around 3k and then died. No codes again. This reads like fuel pump.

 

[rushthezeppelin]

The fuel smell at startup is making me think drippy injectors though. I did have my roommate turn the key to on while warm and me listening to the fuel tank, didn't hear anything. I don't know how loud these pumps normally are though. Going to try again when cold.

 

[SteveH]

Mysterious random power loss and stalling with no codes was the sign of a failing fuel pump on my '99 LX470 at 316K miles. I never had high RPM issues, but had hot re-start and hot weather stumbling problems.

 

[rushthezeppelin]

Mysterious random power loss and stalling with no codes was the sign of a failing fuel pump on my '99 LX470 at 316K miles. I never had high RPM issues, but had hot re-start and hot weather stumbling problems.

Could also be relay although the loss of power then dying once warm seems to point away from that. Seems like relay would be a pure on off situation.

 

[DaveInDenver]

Could also be relay although the loss of power then dying once warm seems to point away from that. Seems like relay would be a pure on off situation.

Relays don't always fail in a binary, they can chatter or get you a weak circuit.

The failure is generally mechanical where the contacts don't rest or close completely. The way a relay works is one state is the rest state, which is the coil unpowered. In this state there's a spring that holds the contacts in position (open or closed, depending). When you energize the coil the contacts are pushed into the other state against this spring. So if the spring breaks one state (energized) is strong but the other isn't. Vice versa if the coil windings are compromised and the force it can generate is reduced it may not have the ability to get the contacts to change state fully. Weirdness can happen, like just one loop of the spring breaks and it's weak or it can jam and still work sort of. Sometimes residual magnetism makes them work funky.

What you end up with is like holding a wall switch half way between on and off, so it can arc and do weird stuff.

In your case it's totally plausible that some failure sitting still the orientation of the relay lets it work but moving down the road the vibration shakes it loose or it comes and goes.

If you think it's the fuel pump it's not a bad idea to pull the relay, clean the blades, shake to listen for a broken spring. You can usually swap it with another relay in the box, like the horn or fog lights or something, which is probably the same part number. Or just replace it on principle, it's an important relay to keep in the spare parts anyway.

 

[rushthezeppelin]

Also called a buddy of mine who is a several decades mechanic. He is leaning towards crank position sensor. Anyone know a way to get torque pro to show the voltage reading off that?

 

[rushthezeppelin]

Hmm got it up to stalling temp and relay is still clicking. Also shook it and no rattling. I know that's not a totally conclusive test and I'm not finding any other relays under the hood with the same model number or color.

 

[rushthezeppelin]

Also the relay hadn't gotten that warm by the time I got failure.

 

[AimCOTaco]

I'd test the pumps delivery after the filters but it's tricky to do so safely. So instead maybe just pull the tank and look at the pump screens and replace the main filter.
This sounds like you get fuel sometimes then crud plugs it up and it acts up. I'd verify the flow parts before chasing the electrical parts. Just my quick 2c..

Crank sensor will usually throw a code, may be hard to monitor in real time with torque but I haven't tried.

 

[AimCOTaco]

It's probably a multispeed fuel pump like the rest of 1/2 UZ's so not just a simple relay circuit, but more likely a relay then the control box driven by the ECU.

 

[rushthezeppelin]

Dangit just realized I only checked the fuel pump relay. If I'm understanding correctly that is just always on with the key at on but the efi relay is what actually switches on and off as the system needs pressure and it's therefore more prone to failure right?

 

[DaveInDenver]

It's probably a multispeed fuel pump like the rest of 1/2 UZ's so not just a simple relay circuit, but more likely a relay then the control box driven by the ECU.

Do they have a fuel pressure regulator? There's also a huge resistor in the circuit and if it's like my Tacoma the theory goes that the F/PUMP relay and resistor are how Toyota does the two speeds. At low demand the relay switches the resistor in to the circuit, which slows the pump. I wonder if the relay fails all that would happen is you get continuous high speed. Would this then cause a fault or would the regulator just deal with it?

@rushthezeppelin , there may actually be 3 relays in the circuit. Power source -> EFI relay -> C/OPN relay -> F/PUMP relay -> Pump. C/OPN is known as the circuit opening. It's like a second safety where the ECU has another set of inputs that it might use if it wants to prevent fuel delivery.

Looking at my FSM it's no wonder none others match, the F/PUMP relay is double acting. In rest it gives full voltage to the pump and energized it switches the fuel pump resistor into the circuit for that additional voltage drop. It may have 5 terminals on it, too.