deanshark

I see, that was lavondag who mentioned that, not the OP, who's question I was answering. Actually lavondag doesn't have the same symptoms now as the OP does, his car wont even start now, which could be coil or T-belt issue.
But with msrdude's car, for some reason the duel voltage on the fuel pump is starting to stick in my head. Not sure if that could be the problem.

msrdude

ok i tested the fuel pump and it was shot (done) So i need a new one.
Quick question on replacing it: Do i have to drop the fuel tank or remove the gas in the tank before removing the fuel pump?

RA40

iTrader: (6)

This older thread:
https://www.clublexus.com/forums/ls4...m-problem.html

Fuel pump is accessible from the passenger cabin once you remove the rear seats.

zukikat

The OP and second guy sound like they've got 2 very different problems...

The OP sounds like a dead fuel pump but he should definitely begin with the diag jumper since a bad fuse or loose connector can also cause problems that the engine computer might actually be able to identify and report. Note that checking for codes, writing them down, clearing them, trying to start the car a few times, then checking for codes again should be done because old codes from prior problems might have been saved up in the computer and may have nothing to do with the current problem...

For the other guy, with a timing problem that keeps the car from running, especially if it starts at all, I'd tend to think the engine computer would see something out of whack and report at least one trouble code to give you a place to begin troubleshooting...

When my Fuel Pump died I used the diagnostic jumper my 94 LS did NOT have any codes stored.
OBD-II (96+ iirc) might be smarter though...

On my car it was DEFINITELY the fuel pump on its' way out when my LS randomly wouldn't start right up or started and stalled right away, then started and ran normally all day, and then a few weeks later it finally wouldn't start at all. Lots of cranking, no coughs or sputters or any signs of life...

The first time it wouldn't start at all and the ECU reported np problems I inserted the FP to B+ jumper and there was about a second delay after the click before I heard the pump kick in and the fuel start to flow into the rails, and after that test jumper was removed I turned the key and the car fired right up and did fine for about 3 more days.
Then after a 50 mile commute to the office I tried to leave at the end of the day, crank but no start, AGAIN...
Inserted the test jumper this time more than once, fuel pump was dead. Maybe an hour's work to install a new auto parts store "LS400 compatible" fuel pump in the parking lot at work 4 months ago and she always fires right up in the blink of an eye every time I turn the key now.

NOTE: My LS had 190k miles and what appeared to still be the factory Denso pump with all those miles on it when it died...