Davenlei

iTrader: (1)

I have a 2008 GX470 with 197K miles on the clock. I was driving home today and suddenly I had no power (no acceleration) and the car was decelerating no matter how much I pressed on the accelerator. There was suddenly no power at all. The check engine light turned on during coasting. As I was coasting to the shoulder I pressed on the gas again and the car let out a small backfire. I got to the shoulder and then called a tow to get the car home.
The car will not start anymore and just cranks over with no hint of even trying to start. I am NOT seeing any Christmas tree of lights or anything and waiting till this evening for my son to bring me my scan tool to see what codes if any there are.

Has anyone else encountered this same situation? Was it the fuel pump? I heard something about a fuel ECU or something being a potential? How do you confirm if the fuel pump is running or not? Any other hints?
I am very handy and work on my stuff but this the first time my GX has let me down in almost 200K miles.

sixbanger

just a few ideas/things to check

check wiring to sensors by the serpentine belt, there is one in there that if routed wrong or breaks away from its clip can rub on serp belt and cause issues.

For fuel pump, if you turn the key all the way forward, you should hear a loud whine in the back as the fuel pump primes. if not, fuel pump or power issue maybe

since it cranks hard, its likely not alternator or battery, but check those connections anyway.

look for any rodent chewed wires or nests.

good luck

chiph9

When it cranks, does it turn over at the same speed as it always has, or is it faster?

Chip H.

LeX2K

I'm thinking the same thing timing belt broke.

Davenlei

iTrader: (1)

Same speed.

Davenlei

iTrader: (1)

I had the timing belt replaced for the second time about 5,000 miles ago. I replaced at 95K miles the first time.
When it lost power it did not make any unusual noise or shudder or anything. It just suddenly lost power like a light switch turned off.

I checked the fuel pump relay and switched it with the DEF relay which is the exact same part number and tolerance and it still is doing the same no start. I was thinking I was going to pull the carpet and apply 12 volts directly to the pump to see if I hear the pump motor run or not.
Is there a schrader valve for the fuel rail on these things to fuel test pressure?

tz693

I would check fuse first and get a code reader to read code.

Davenlei

iTrader: (1)

I ran a scan tool and there are no DTC codes.
This is strange.

tz693

Not sure the general OBDII reader can read much Lexus specific information. Suggest to down load a copy of Techstream program.

Davenlei

iTrader: (1)

Good point.

Davenlei

iTrader: (1)

Ok so I ran tech-stream and there are no DTC codes. I removed my back seat and opened the fuel pump access cover on the floor board and confirmed the connections were solid. I turned the ignition to the 'on' position and there was no noise coming from the fuel pump when it should be priming the system. No motor noise or anything. I then triggered the live test for "Fuel Pump Speed Control" and there was no noise or anything coming from the fuel pump either. To confirm I was able to perform tests with the tech-stream, I triggered the started relay and it was clicking as expected so I know I was able to send commands to the ECU.
I checked the power to the wires and I was getting 12v at the center pin on the row with three pins (top row has two pins and bottom row has three).
Is that pretty conclusive it is the fuel pump? Are there other tech-stream values I should look at or other live tests I can run? How can I run 12v to the pump to confirm there are no middle systems stopping it from running? Which pins do I connect power and ground?

tz693

See if you can figure out something from this part of the manual.

Davenlei

iTrader: (1)

Hmmm, on the document you sent, on 11-10. it talks about testing the pump by applying power and ground to the terminals on the connector but the connector is only two prong. Hmmmm......

Instead of futzing around with it and throwing the parts bin at it, I may just get it towed to a repair shop and plunk the money down for the inspection and if it is the fuel pump then spend $800 for the pump and labor to drop the tank and replace the pump. Terrible that they did not make the access hole in the floorboard anywhere near the size needed to change the pump with the tank in place like several other manufacturers do. Sucks that I can touch and interact directly with the cover from the hole but can't change it that way. I know that some people recommend cutting the access hole much bigger to allow changing the pump from above but I don't want to give the eventual next owner of the car something hacked into to save a couple hundred dollars of labor.

Davenlei

iTrader: (1)

Ok, new update. A shop I called that works primarily on Lexus vehicles told me to pull the intake off the throttle body and to have someone crank the engine while I give a couple short sprays of starting fluid at the throttle body. I did that and the car fired up for a few seconds like normal and then died since I stopped spraying fluid into the throttle body. So this eliminates pointing to the timing belt/timing, mechanical engine issues and ignition system. More evidence it is the fuel delivery (fuel pump).

chiph9

I can't really zoom in on your photo, but it looks like the connector doesn't have a pin on the bottom-right. So there probably are only four wires.

The diagram I have shows a ground on pin 5 (WHT/BLK) and switched 12v on pin 4 (BLK/RED).
The switched 12v runs to the fuel pump relay in the engine compartment. The C/OPN and EFI relays are also involved.

The fuel sender uses pins 2 (BRN/RED) and 3 (BRN), and runs directly to the instrument cluster.

Chip H.