Och

iTrader: (3)

In the recent couple of weeks my 01 GS430 developed a problem starting up. I need to crank it for a long time before it finally fires up, and sometimes it will only fire up on the second try. After it starts, it seems to lag a before reaching around 2500 RPMs, and then takes off like a bat.

Replaced spark plugs over the weekend with no result. Everything in the car is maintained well, new fuel filter, timing belt/water pump were recently replaced,
throttle body cleaned, new o2 sensors, new MAF, etc.

What can it be? There are no codes whatsoever. Could it be the fuel pump? And if its the fuel pump, would it be likely for the car to start hard but run well at higher RPM range?

Och

iTrader: (3)

Oh yeah, another thing... lately it seems my fuel mileage took a huge crap, the car noticeably wastes more fuel than ever before.

DASHOCKER

iTrader: (2)

Long cranking is a sign of a bad fuel pump.. Was your old fuel pump bad? They seldom need replacing unless you encounter the symptoms you mentioned in your original post. I am still on my original fuel pump with 106k on the clock.

McKrevice

iTrader: (1)

I'd say pump like mentioned. When you turn the key, pressure builds up, but the pump appears to be losing pressure causing it to crank and crank. Not sure if our cars have a fuel pressure regulator, but if so, that might also be the issue.

Och

iTrader: (3)

Hey guys, before I drop money down on a new pump, is there a way to test it to know for sure? Like testing the fuel pressure?

denut-L

iTrader: (11)

My brother had the same problem but he has a camry and we put in some fuel injector cleaner and problem solved.

No hesitation at low rpm's and start up's

GL

GS4_Fiend

iTrader: (22)

You would need a fuel pressure gauge. The pump is probably weak. Also make sure there are no vacuum leaks.

jhill20

iTrader: (1)

First of all Bad fuel pumps are not common with toyota/lexus. That being said, it does "sound" like a fuel delivery issue.

You will need a fuel pressure gauge, with most likely a certain fitting to access the fuel line, not remembering off the top of my head if it has an access port or not.

GS4_Fiend

iTrader: (22)

It's lacking in spark or fuel... Or even BOTH. (CKP)

knotsofast

I had similar symptoms, so I decided to run through a tank with fuel system cleaner. It's gotten better but not completely gone. I am now on the second tank w/cleaner; hope it clears up.

skperformance

iTrader: (6)

At first it sounds like a pump but if it goes away at higher RPM then it is not since that is the reverse of the problem it causes since it starves the engine as it increase in demand .

I would lean to a vac leak or maf issue first.

Throttle body cleaning and seafoam are good cheap starts before replacing anything to get a base line.

Och

iTrader: (3)

Well, I'll be taking the car to a professional hopefully tomorrow. I tried new maf, and bought two new coils, which I kept swapping in until I got though all eight. No improvement so far.

I think its probably fuel pump/pressure regulator/fuel dampener issue, or maybe even injectors issue. I'll update on the progress.

P.S.

This is the first real issue this car has had in its 115k miles.

Och

iTrader: (3)

So now I pretty much know for sure the fuel pressure is too low. Theres a fuel hose going up to the engine, and compared to the same hose in my friends GS430, it feels 50% less pressurised, both when the car is on or off. I wonder now if thats the fuel pump or leaky injectors.

knotsofast

Well w/mine, I found the previous owner replaced the vac hose on the PCV valve with plain rubber. Over time, line was collapsing from the suction. I swapped out with vac line; starting is back to normal.

BLAZE

iTrader: (2)

Check the battery, when was the last time you replaced it ? These cars run pretty f,cked up with a dying battery.