ghoffner

If you're serious PM me. My salesman, in Dallas, can do $60k on a MSRP of $73k. That was as of a few weeks ago. I'd imagine you could get $58 or so.

mirza

dealer told me that there are 2 fuel pumps in the car? one on the left of the fuel tank and one on the right. Doesnt sound right to me to have 2. can somebody confirm that they dont know what they are saying?

JT2MA71

iTrader: (7)

There are 3: 1 in the tank for the port injection and one on each valve cover for the high pressure Direct Injection system.

mirza

so 2(1 for each bank) on the head of 8?
But only one in the tank which is what I assumed.

lobuxracer

iTrader: (2)

Not exactly. One in the tank for all of the fuel, and two HP pumps on the valve covers for the direct injectors. If the in tank pump fails, the engine will not start. There is a passive "jet pump" inside the fuel tank to transfer fuel from one side to the other because the tank straddles the driveshaft.

The fuel system isn't exactly simple, but if you understand EFI principles, it's not too complicated either. The biggest thing about this fuel system is the DI pressure is managed by the ECM, and there are no external returns to the tank, only an internal return whose outflow keeps the subtank filled above the level of the main tank. The diagram below is close, but it implies there is a return from the HP fuel system. The diagram for the HP system shows very clearly there is no such thing.

FWIW, after reading through this whole thread, it sounds like there is a problem with fuel pressure control at the in tank pump. Toyota have used variable voltage controllers on fuel pumps since the MkIV Supra with varying technologies to minimize the volume of fuel the pump actually produces. There is a huge emissions benefit to this because pumped fuel creates more vapors than fuel sitting stationary in the tank. It also reduces stress on the other fuel system components and reduces overall energy consumption.

A key element to troubleshooting this problem is the burned pin on the wiring harness connector. This only happens when two problems are present - first, there needs to be more resistance than expected at the connection and second, there needs to be high current compared to expected. I am pretty sure this is why the techs from Japan were sent to investigate. Pins are sized according to expected electrical load, both peak and sustained. When pin burns, something is operating well outside design parameters. What this says to me is the pump is working too hard continuously. This could be a sensor issue (the fuel pump controller is not getting good data, so the controller is overworking the pump), it could be the software in the controller, it could be a restriction in the return path inside the fuel tank forcing the pump to work hard than it should, or it could be something I have not thought of entirely. Regardless, I really doubt it is the pump itself and I'm a lot more inclined to believe it is how the pump is being controlled. The actual fix for this problem will very likely be something in the way the pump is controlled, or the way it is installed in the tank. JMHO as a backyard mechanic who has worked on a couple of things over the years and troubleshot some complex systems as a job.

And if anyone says something about the HPFPs again, I'll know they're not paying any attention nor do they have a clue about how this particular system was designed and built.

JT2MA71

iTrader: (7)

Thanks for the explanation, Lance. Do you think the "humming" noise that is heard, which is obviously the pump, is from the pump gone bad, or the controller running the pump at lower than it should be duty cycle? I know that I can make my Weldon pump hum if I change the table parameters on the MoTeC to really low duty cycle. I also was experimenting with my electric fans dependent on vehicle speed, and found out than at low duty cycle, the fans make a humming noise when the duty cycle is too low to turn them.

lobuxracer

iTrader: (2)

Running at too low a speed would make a lot of sense from an electrical perspective. It damages the motor windings by overheating them. If you've ever disassembled a starter that has been abused by running under load too long, you'll know exactly what I am talking about. When the speed increases the individual windings have less on time per revolution and they tend to stay cooler. Also, at low motor speeds the motor draws a lot more current which would explain why the connectors are melting/welding together. On a starter, the inrush current is 300+ A, but quickly drops as soon as the motor gets up to speed (by motor I mean starter, not the engine).

If you've ever locked an engine, you know the starter smokes in seconds if the Bendix can get the gear engaged.

mirza

Thanks for the writeup Lobuxracer. I drove the car hard to pick up my wallet and the car stopped making the humming noise which confirms what you are saying.
So the solution to the problem is to drive hard

Ne1tHeRe

iTrader: (3)

I got the "drive hard" part covered hahahaha

lobuxracer

iTrader: (2)

I just took a long look in TIS to see what information Lexus has for repair techs on this fuel system. They don't have much. The troubleshooting methodology is very basic and simple R&R "defective" part. No information on how the fuel pump controller ECU works even in the New Car Features. Pretty odd for Lexus. They usually have lots of information about this kind of thing.

I validated one other thought - this pump is used in a whole LOT of Lexus vehicles and has been used since '07:

No one in the IS F forum has posted anything about fuel pump noises or failures. I've got 125k miles on mine including lots of sitting in Atlanta traffic as well as track time, and I have zero experience with fuel pump issues. What am I saying? It's not the fuel pump...

And at the end of the investigation, the RC F has a fuel pump ECU where the IS F has a relay and a resistor. IS F is low/high speed where RC F is variable (no idea how many steps because the manuals do not say). Fuel systems are like guns. The more simple they are, the more reliable they are. Sounds like there will be new fuel pump ECUs for the RC F. The GS F uses the same technology. Might be new FP ECUs for GS Fs too.

Ne1tHeRe

iTrader: (3)

I may have jinxed myself...noticed a delay/hesitation when driving yesterday. Just took the car out for a spin and noticed a big delay and hesitation when accelerating in standard auto S+ mode. Switched to full manual S+ and was driving it through the gears to redline...first it was sluggish/hesitant and noticed a high pitched whine (possibly from pump) from the rear when accelerating. Drove it some more and it started getting better. Will try again and see if the hesitation and noise goes away or if it comes back. Not sure what is going on but it does not make me happy with less than 600 miles on the car

Joe Z

iTrader: (10)

Great info Finally..!!! Lobuxracer

Did you mean the Fuel Pressure regulator is the same unit across those models??

The RC F has its own part number for the fuel pump...

So does the IS F, shared with a few other models.


Joe Z

Ne1tHeRe

iTrader: (3)

Yes, I second that...just read it after I posted. Hopefully, my issue resolves itself and/or they have a FP ECU reflash fix (or replace with new FP ECU).

4everkidd

iTrader: (2)

FINALLY someone who knows what they're talking about!

As i've said from the beginning, the ROOT CAUSE is not the fuel pump... Why else would most of us have zero issue, and those of you who do have issues have several back to back failures.

Thanks Lobux, sell that ISF already and pick up an RCF so we can have you straighten people out on this page more often

mirza

dropped car off friday explaining why they should listen to me. they got a pump in yesterday and I am picking the car up today
That was pretty quick and I got to drive the 2016 RX for a few days. My wife wants one now.