cschroder

Here we go:

2006 gs430. I live in the country, went out the other day to get in and go and mylex had other plans. I would start it like normal and then it would die, no matter what i did with the accelerator pedal. Been down this road before, living in the country, mouse chewed through the mass air flow sensor wires. Checked the codes got the 2 that throw when your MAF is unplugged..easy enough. 20 minutes, a little solder, and heat shrink later I was outta here. Now for the interesting part.

This morning i went out to get in and go, hit the button, started right up, ran a little longer than when the MAF wiring was chewed through, and quit. Figured i screwed up somewhere, so i pulled out the trusty code reader and low and behold...no codes. HMMM started screwing around with it and found out that it would run if i pumped the accelerator while it was running. I came on to clublexus to see if anyone else had the same problems, found the problems but no solutions. searched the internet and found the same problems, diagnosed by dealers, solutions ranged from ecu's, wiring harnesses, alternators, that's when i figured umm this cant be a $3000 issue for Christ's sake it runs. Time to figure it out.

These cars are kinda wacky sometimes, here's how the fuel system works:
you start the car, the ecu tells the fuel pump to run full blast(that's why all lexus' stink so bad when they are first started), then if the ecu doesn't think there is a high load and you aren't starting, it tells the fuel pump to slow down. There is a symphony of miracles that must unfold to make this happen. So i got out the trusty manual and started at step one and went from there. checked the fuel pump, the accelerator position sensor, throttle body, all those crazy relays in "engine room #2 junction block" called "Integration Relay (Unit A), ohm'd out the wiring harness, checked ecu voltage, ohm'd the fuel pump, and finally at the last and EASIEST step #13, INSPECT FUEL PUMP RESISTOR. One broken, chewed through wire, on the resistor and your lexus will not idle and it will not throw a code. It will die because the fuel pump is not getting any voltage. There's nothing wrong with the fuel pump its just not getting any power. When you step on the gas(high load is detected) and the resistor is bypassed by another relay and zoom zoom away you go full speed, take your foot out of it and it will die of starvation. Total relays in the fuel system: 5 all opening and closing at different times to achieve lower fuel pressure for idle and higher fuel pressure for high load.

A lot of the components that I Ohm'd out were "out of tolerance", but the car runs fine, I can really see how a dealer could just go to town with this and finance his new boat. Kinda funny how the cheapest and easiest thing to check is the last thing in the service manual to check. Guess my second grade teacher was right, read all the instructions first before you do anything.

Here's some pics since I know everyone loves pictures:

https://drive.google.com/open?id=0B0...Wwyb1dGcUdIWjQ

https://drive.google.com/open?id=0B0...ndXejhyaXR3dnc

https://drive.google.com/open?id=0B0...1RlV29RTGtablE

https://drive.google.com/open?id=0B0...kN2bE0wVWZMRTg

https://drive.google.com/open?id=0B0...3pITUFUVmxEWWs

fixed the wire, put it back together and shazzzam started right up and idled just like it should.

brainsurge

Your pictures don't work, since google drives works only for ppl with email invitations.
thanks for sharing this!

ibidu1

iTrader: (1)

I wonder if you short circuited the map sensor. Because most likely on engines the map sensor will not allow the car to hold idle

cschroder

Fixed the pic links. They are public now.

cschroder

Nope, a wire from the resistor was broken, fixed that and runs fine now

burny

Is there a code? If the igniter or any of the coil paks or wires have failed there is a safety feature where the fuel flow is cut off. That would basically start your car for 2-3 seconds before it cut off from lack of fuel.

aliphier

I have a problem with my Lexus IS250 (2006 model), it starts and dies on me seconds later, sometimes it cranks and fail to start. But when it starts and I immediately keep my foot on the gas pedal, the car stays running until such a time when i remove my foot off the gas pedal. The car just loses the rev count and dies when the foot is removed from the gas pedal. My mechanic did all he could but seem not to crack where the problem could be coming from. I have since changed the fuel pressure sensor but that didn't help. The thread above looks like what can help me but the problem is that i don't know where the fuel pump resistor is located. Funny enough, my mechanic doesn't know where it is located

Nathaniel88

Did you manage to find out where it is mate?