sung35

I searched here, left and right. I googled the internet. But could not find the answer. I am having issue with my 2000 GS400. It cranks, engine catches, but stutter and dies right away. It is like the engine gets some gas when starts, but not when the engine catches. I replaced throttle position motor , throttle position sensor, throttle body level sensor (also call accelerator position sensor). Same problem still exists. I now think that it is because the fuel problem. I want to eliminate the fuel relay before going for the fuel pump. So, does anyone know where the fuel relay is located?

TrueGS300

You'll know if its a fuel problem if you introduce an alternate fuel supply and it runs. Just pull the intake boot off and have someone crank while you spray the throttle with brake clean. If it runs while you continue to spray in small spurts, you have a fuel supply issue. If its getting any fuel at all, your rely is working fine. Possibly a very weak pump. Id try the brake clean thing and if it runs, check fuel pressure. If it still doesn't run, it's another issue.

sung35

Found something here indicated the relay is n the fuse box near the battery. I open the fuse box near the battery. Here are the 4 relays I found in there:

sung35

None of the above 4 relays is for fuel.

sung35

It is too cold here in northwest. I might wait until next Spring. Just want to gather info before doing the work.

Thanks TrueGS300 for your suggestion.

MikeFig82

iTrader: (13)

https://www.clublexus.com/forums/gs-...e-diagram.html

Letsride

I know you a tech and all but please dont tell members to spray Brake Clean into their intake to test for a fuel problem. That is not the fluid to spray in there......use starting fluid. Take apart an engine that someone has used brake clean to try and start and tell me what you see.

sung35

@Letsride. Thanks for the info about the staring fluid. I used the MAF sensor cleaning. Not sure if it is safe. Anyway, is the starting fluid the same as the starting fluid for staring a bon fire or barbecue with wood and charcoal? Or staring fluid specifically for starting up the car? Do they sell it at the auto store? Thanks.

sung35

@MikeFig82, thanks for the diagram. The EFI is the fuel relay I think. I didn't look into the inner side of the lid fuses when I opened it. Maybe I should see the same picture as posted. Will try to take out that EFI relay and test it out. Hopefully that is my problem. I don't want to replace the fuel pump . The fuel tank was filled like 5 min after the car died, so the tank is now full and i don't want to suffer the fume.

sung35

Found the info about the staring fluid by Googling. Didn't know they sale such product. Now I know. ClubLexus is great. And thank to Letsride.

TW99GS300

EFI relay is essentially for the ECU triggers. The fuel pump has an ECU in the trunk. Have someone verify the pump primes when you turn ignition on.
Also, when a crank sensor fails the fuel pump will not engage.

sung35

Haven't try the test for power at the fuel pump. I will try that too. Thanks TW99GS300

sung35

Tested the EFI relay today. It is good. Was hoping it fails. Sigh

eicca

Verify whether or not it'll run on starter fluid, because starts-then-dies usually means a sensor issue, in my experience. MAF, crank, cam, etc.

All the fuel pumps I've had die would run for a while then crap out, or just not start the car at all.

sung35

Right now everything before the throttle body has been removed for access to the TPS, TPM, APS. MAF if not working the car should still start up, but run like crap. So I would eliminate the MAF sensor. How do I test for crank and/or cam sensor? Thanks.