talegunner

OK, First, I'm 'old school' mechanic of 40+ years. Totally lost in this technology but don't wanna stay there! I have a 'no start' condition on my '99 GS 400. Cranks fine. I changed parking slots in the morning, it ran fine, then in evening, my wife got in and it wouldn't start. I have eliminated the fuel and it appears the problem is with ignition. The procedure I'm familiar with was to simply pull a spark plug boot, place a tester between that and the ground, crank engine to see if you got fire. If not, then you work backwards..More times than not it was the electronic ignition module. Is there anyone who can clue me in on the procedure to effectively check the ignition system on these guys?
Thank you

AgedGS

Better late than never, I guess, but I just saw this....If this is even still an issue, have you gone through the basics, like fuses, relays,grounds, etc? If it started & moved, and then wouldn't restart, I'd think maybe a fuse or something of that nature. Most ignition components wouldn't just go out without some advance notice.

talegunner

Yes sir, it is still an issue. With our weather situation as it is I've not been able to go much further, but yes I have checked the basics with the exception of the fuel regulator, of which I am not aware of its location as yet and too cold to spend any reasonable amount of time looking. However, I have replaced the fuel pump, but not the filter, checked all the fuses, twice, even read the codes and see nothing so damning as to cause a 'no-start'.
I also checked the spark and were this a conventional ignition system I would say it has very strong fire but seems slow. With points, dura spark or HEI that I'm familiar with, the fire should be rapid and continuous. If I were to guess, on any other system I would have said that it fires at the approximate rate of every 5th rotation of the crankshaft.
I had planned to check the fuel regulator, (though it just doesn't act like a fuel problem) and pressure, and if it checks out I may just tow it to a shop. I'd much prefer not to, but I just don't have enough info about these systems to go any further.
Thank you for the reply.

tiguy99

Have you checked the starter relay?

talegunner

Well, I answered via the 'quick reply' but am not seeing it posted so I'll answer again. Please excuse if there is a duplication.
["Have you checked the starter relay?"]
Assuming the starter relay in a Lexus serves the same function as any other car that uses them, which is connecting the ignition switch to the solenoid, thus cranking the starter... then, there is no need to check it as it cranks just fine, but just doesn't start.

AgedGS

What did you do to check the fuel? Pressure test? Also, I'm not immediately sure as I'm used to the 3.0's, but if there is an ignitor chip, perhaps that could be the cause. Maybe trouble shoot that & see if it helps.

MikeFig82

iTrader: (13)

The last time my GS400 wouldn't start. It ended bieing I needed fuel in the tank. It was bone dry yet the needle showed I had about 1/4 in the tank. I trouble shot the crap out of it I kid you not LOL. I had just got a friend to change out my injector orings the day before. The next day I went to the store and it wouldn't crank back up. Then eventually it did just enough to get it home. As I was pulling in the driveway I could smell fuel. So I check the injectors again, and one was leaking fuel. So I figured it was my problem. Fast forward got all the work done. I actually did both sides of the rails to make sure all the rings were seated properly.

I couldn't crank it back up 3 days I tried all kinds of things cleaning the MAF , blah blah you name it. I finally got frustrated and pulled the pump. Like I said the tank was bone dry.

Iceofcali