hughjorgan

I have a 2002 AWD RX300 with approximately 83,000 miles on it. I have owned it for a month. When I got it there was a CEL for the A/F sensor which I replaced with a Denso sensor. The code cleared and never returned (may not be related but I figured I should mention it). It is in my garage when I'm home and was stored in a garage by the first owner. I sat for about one year prior to purchasing it. I work 3rd shift here in the midwest. One morning it was sub zero and I tried to start it. It turned over fine but would not start. I figured it may have a frozen line. I got a ride back to it during the day when it was in the teens. It started up and I drove it home. It has done this several times. I put a bottle of heet in it and have only used 91-93 octane fuel. The problem has happened several more times including one time in my 35 degree garage. I was unsure of the status of the battery so I replaced it just so I know where I stand. Swapped the EFI relay with the horn relay. Nothing. It has never hesitated or indicated any problems when running. If it starts, it runs great. I did notice that I don't hear the fuel pump priming when I turn the ignition to the "on" position. Even though I never hear the pump priming it still starts most of the time. I can't drive it until I fix the problem or I will end up stranded. Is it possible the PCM/ECM is defective since that is what sends the signal to prime the pump? Hope someone can help.

salimshah

If the starter can spin the engine at normal speed then the battery is not a suspect.

That leaves us with spark, timing, air and fuel.

Lack of air can be mitigated by holding the gas pedal partially (see IACV discussion).

You can test out fuel delivery by measuring fuel pressure at the engine block and flow rate. A simple go no go test can be observed by seeing the presence of flow. You can also byepass the +12v and go directly to the pump. Hard do diagnose would be intermittent pump failure .

Spark can be verified by taking plug 2 out and laying it on the block in a shaded area.

I hate throwing parts, but after verifying spark and air, I would change the pump. Not precise way of doing things but for intermittent failures we have to resort to this.

Salim

ps: Welcome to CL

hughjorgan

Do you have any idea why it won't prime/pressurize when the ignition is turned to "on" (not to start)? I hear three quick "clicks" coming from the relay box. Would the pump be bad if it always runs when it is started? I suppose there could be a wire short somewhere?

salimshah

The procedure is to hot wire the pump or measure 12v on the pump connector. You can disconnect the quick connector at the engine side [way below the power brake booster] and see if you get fuel when you have 12v at the pump. Please exercise needed caution [cold engine, no open flame etc as you will be bleeding fuel].

I have not studied RX supply to pump, but all vehicles employ some sort of fail safe mechanism that cuts out the supply to the pump in case of an accident. You will hit the ecu or some control circuit and it would not be easy to debug. Bypass is the only sure way to eliminate/isolate the problem.

Any short in the system results in popping of fuse or fusible links. You can have an open.

Everything is robust (assuming no one has compromised/worked on it) and fuel pump is the weakest link in fuel delivery system. [note I am playing odds]

Salim

hughjorgan

Well I would ridicule myself more harshly if I had know all the facts. There wasn't anything wrong with the car. When I bought it I found a key on the floor. A key without the remote lock on it (later identified as the "Flat Key"). If you own this vehicle then you may have figured out what went wrong. Having never owned a vehicle with anti theft or a built in keyless entry, I didn't know the difference between the keys. I thought it may be a valet key or spare for starting the car in the cold and locking the doors. I started thinking about what was different when it wouldn't start. It was when I was trying to start it in the cold to let it warm up. I used the "flat key" to try to start it. It didn't start because it doesn't have a chip in it. It was supposed to have a card with it that has the chip to allow the vehicle to start. That card has apparently been lost. At the time I tried the other key after the failure of the flat key to no avail. I didn't know at the time that the use of the flat key activated the anti theft for 60 seconds before I could try again. This "flat key" is mentioned on 1 page of the owners manual! Once I found that page it all made sense. All is well. Thanks for your attempt to help. No one could have known what was wrong since I had no idea I was causing it. Hope someone else hasn't made this mistake. It took a lot of thinking and mental tracking of each event to figure out this issue. I'm just glad I didn't start replacing parts before this discovery!
PS Love this site! Lots of great information and troubleshooting.

Carver

Thank you for returning to share the resolution, much appreciated.