FancyCamry

1999 Lexus ES300 1mz vvti, 130k miles. I was having wierd issues when driving about a month ago. Sometimes when I put my foot down on the gas, the car would sputter and the rpms would drop to almost 200, and I would have no power until I pushed the pedal to the floor, which would then shoot the rpms up to redline and I would lurch forward.

The car was already in need of some maintenance, so I tore it apart to do the valve cover gaskets, spark plugs, intake plenum gasket, pcv valve, fuel filter, and fuel pump. I got it all back together, and it cranks, but won't start. I triple checked that everything was back together correctly, which it was.

I decided to start with a fuel pressure test since I couldn't hear the pump priming when I cycled the ignition. I hooked the gauge up to the outlet of the fuel filter, before the fuel enters the fuel rails. 0 psi when I cycled the key, 0 psi when I cranked. I replaced the efi relay and the circuit opening relay with new ones, still no start or fuel pressure.

Attached is a picture of the wiring layout for the fuel circuit. I metered the inputs to the circuit opening relay from the FC wire/ECU, and I have less than 0.5 mV on both input pins, both when I cycle the key to on, and when I'm cranking the ignition. So for some reason, the FC line isn't supplying power to the circuit opening relay. Does anyone have anymore insight into this? Doea it sound like a bad computer? Any way I can confirm this? I don't have a high impedance meter, so I don't want to directly meter over the ECU terminals. If anyone has any ideas, I'd love to hear them.

LeX2K

Does the security light go out when you insert the key into the ignition?

FancyCamry

Yeah, it does

LeX2K

To be clear, the fuel pump only runs when the engine is cranked or of course when running. There is no "fuel pump prime" when the key is in the ON position. Have you checked for spark and injector pulses? Are you sure the crank position sensor is working? In my experience if that is not sending a pulse to the ECU the engine won't start and you'll get no codes.

Arsenii

Hello,

See if the CEL is on when the key is in the ON position, if not, check EFI an IGN fuses.

The thing is that the ECU supplies Ground for the coil in the relay, 12V are constantly supplied to both the switch and the coil of the Circuit Opening relay, but only when the EFI relay is on (aka key is in the ON position). Check if you have voltage between two Coil pins in the Circuit Opening relay while cranking the car (I would suggest using test light for it); if so, ECU supplies everything it should. After that, check if relay works at all by supplying 12V to it and seeing if it will switch. If that's good, check if you have power going to the pump while cranking the car. If you have power, check if the pump is working; if not, check the wiring form the relay to the pump.

Hope this helps and best of luck!

ghaiks

I'm having similar problems with my 93 ES 300. The car is running very rich and is guzzling fuel. Before taking it to the mechanic it was blowing out some smoke from the exhaust that smelled like fuel and was running as OP described. My mechanic has replaced quite a few things so far including the alternator (battery light was on and not charging properly), MAF, spark plugs, ignition wires, both O2 sensors, replaced and inspected hoses.. list goes on. He ran a bunch of tests for the injectors, engine compression, and fuel system and they were all good. It just rolled over 200,000 miles.

He's ruled out a bunch of issues and is trying a ECU swap this week to a re-manufactured unit to see if it resolves the problem. Fingers crossed!