pinkfloydx Posted August 3, 2012 Share Posted August 3, 2012 hello, have a 1999 es300 that's getting no power to the fuel pump, I've checked the efi fuse and cir opn relay and iv also checked the pump with 12v directly to it and it fires right up, that leaves me thinking there's something wrong with the fuel pump ecu, if this is correct exactly where is it located and is there a test i can do the find out if its bad? thanks. Quote Link to comment Share on other sites More sharing options...
landar Posted August 4, 2012 Share Posted August 4, 2012 and you verified that the relay will close and supply power to the fuel pump? In other words, you should be able to "spoof" (artificially duplicate) the signal from the ECU by closing the relay right at the relay and hear the pump running. This verifies that the wiring and connections back to the pump are all good. If that all works and it is just the ECU signal failing to energize the pump relay, then maybe theft deterrent is activated? Quote Link to comment Share on other sites More sharing options...
pinkfloydx Posted August 4, 2012 Author Share Posted August 4, 2012 thank you for the reply, when i put my finger on the rely and have someone attempt to turn the car over the car cranks strong and i can feel the relay pop which i assumed means its good, i also switched it out for another relay in the fuse box of the same specs and still no power to the pump, how do i go about spoofing the relay like you mentioned? this is family members car so i don't know it like the back of my hand, just trying to do the best i can, if theft deterrent was on would the car still turn over? thanks. Quote Link to comment Share on other sites More sharing options...
landar Posted August 4, 2012 Share Posted August 4, 2012 Well, to spoof the operation of the relay you would simply remove the relay and find the contact pins. Then short the pins together with a wire. You have just manually done what the relay would do. Now, you can also (if handy with a volt-ohm meter) check the voltage on one side of the relay contacts and get +12v. The other side goes to the fuel pump so you will see zero. Another thing you might do is check the resistance across the relay pins with the relay removed. You should see the DC resistance of the pump motor winding...probably in the 25-50 ohm range (dont hold me to that, just a guess). If you do all of these things then you know the wiring and connections to the pump are all good. The issue would then lie with the signal to the relay primary coil. That gets trickier. Quote Link to comment Share on other sites More sharing options...
pinkfloydx Posted August 6, 2012 Author Share Posted August 6, 2012 thanks again for your informed replies, i have an update, as stated before I'm not to familiar with these cars and am just going be the research i have done so far, i think the pump has been kicking in this whole time i didn't know the pump only kicks in after the key is turned to start, i was only turning it to 12 volts and expecting to here the pump, "like on my own car" the car starts when it wants to after many tries, when its running it feels great, no jerkiness or hesitation, then after a while the car just dies and cuts off with no warning at all, any ideas would be greatly appreciated, thanks again. Quote Link to comment Share on other sites More sharing options...
landar Posted August 8, 2012 Share Posted August 8, 2012 Ok. Now it is beginning to sound like a sensor (cam or crank) is intermittent. But thats just speculation at this point. When it cuts off, do you get any codes? (I am guessing "no"). You now need to isolate between ignition and fuel. Know how to do that? Quote Link to comment Share on other sites More sharing options...
RamRodES300 Posted January 1, 2021 Share Posted January 1, 2021 I have 03 es300 lexus, no power to fuel pump.I've done soo many tests before. I change the plugs, checked for spark, changed the camshaft position sensor (got a code p0345/p0340/p0341). After changing with a new sensor, got code P0348. With my car jumped to another running car, I sprayed starting fluid directly inside the intake and it started right up, then died. We connected a tester to the battery (a bypass tester) that shows us ground was good and getting power at various point of interest concerning fuel and ignition. The fuel pump is not recieving power, when we bypassed with the tester after spraying more starting fluid in and cranking, it started and stayed on, once released it died. So for sure no power to the pump. Sound like security to you? @ Randall Quote Link to comment Share on other sites More sharing options...
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