Lexus es300 fuel punp wiring
05-20-21, 02:00 PM
#106
Driver
Thread Starter
Thank you for the info...yes to trace it once i got the efi wire disconnected at the relay I tied it to a jumper to my + battery then went searching the plugs until my light lit up
Last edited by Brian97S; 05-26-21 at 09:21 PM.
05-20-21, 04:07 PM
#107
Pole Position
Make sure to take a lot of pictures before you do so, just so that you won't confuse anything when you will go to put it all back together.
05-26-21, 11:30 AM
#112
Pole Position
Disconnect the Fuel Pump Pigtail, and connect any Headlight Bulb to Pins 4 and 5 of the Pump Pigtail; to connect the Bulb, go to the junkyard and cut some wires off of O2 sensor (which are shown in this post), those connect right up to pretty much any Toyota connectors. Then get an in-line fuse holder (like this one) and a 15A fuse for it, connect one of its leads to the Positive Battery Terminal, and the other to the Bottom-Most Pin of the Circuit Opening Relay. With this setup, you should see the Headlight Bulb light up as bright as it can go. If that's the case, disconnect the in-line fuse from the Positive Terminal and connect it to the Center Pin of the Circuit Opening Relay (the one right above the Bottom-Most Pin that should now be occupied with the other end of an In-Line Fuse), ensuring proper contact, then turn the Ignition to the ON position and see how bright the Headlight Bulb would light, if it will be dimmer than in the first case, then it is the fuse box, if the brightness stays the same, then it is the Pump to blame.
Hope this helps and best of luck!
05-26-21, 11:39 AM
#113
Driver
Thread Starter
So even though that pump will run forever when the circuit is closed it could still be the pump? I don't think so . I want to be 100 percent sure that that is the problem before I replace that pump .
Last edited by Brian97S; 06-01-21 at 02:21 PM. Reason: This pump has
05-26-21, 11:57 AM
#114
Driver
Thread Starter
The wrecking yard thing is not an option. I am gonna double check the circuit again before I replace that pump .I will post results when I have them.
Last edited by Brian97S; 05-26-21 at 08:51 PM.
05-26-21, 10:06 PM
#115
Pole Position
If you made it that far, and already know why the car doesn't stay running, so it would be weird to say the least to tell the mechanic that the car just starts and then dies, since the mechanic will have to go the same route that you did. What you do need to say is "The car starts and then dies, but when the power is fed directly to the pump, the car stays running". That immediately gives an insight on what the issue is, and where to look.
In your particular case, the pump appears to be fine, your issue is that the pump is not getting enough Power to create enough Pressure, though it is enough to prime the system before starting, hence why the car starts and then dies.
My theory right now is that you have a damaged wire somewhere, which is not allowing enough current to go to the pump, hence why it still manages small loads, but fails to keep the car running. The reason why I think so is because you conducted a test, where you connected 12V straight from the battery to the pump, and the car ran fine. This implies that the pump is working, and it is the issue with the 12V supply.
In one of your earlier posts, you wrote that the Test Light lit Dimmer when you connected it to the Relay Socket, which probably indicates that the wire that feeds the Pump is damaged in some way, hence the reasoning behind the test I described earlier.
The theory behind the test I explained in my previous post is to actually pinpoint where exactly are you losing that 12V supply. The Headlight Bulb serves as a big fat load source, which gives you a visual of what is going on. When you add power straight from the Battery through the In-Line Fuse, you are bypassing the Fuse Box and send power directly to the Pump, which verifies that the Positive Wire going from the Circuit Opening Relay to the Pump, and the wire from the Pump to the Ground are intact and solid. When you connect the In-Line Fuse in place of the Relay, you are checking the wire that actually supplies those 12V to the Pump, which is actually where I think your issue is.
Are there any specific reasons why the junkyard is not an option? It is the only place to get parts right then and there, and a lot cheaper than at places like eBay. Besides, it is a great place to learn without the risk of breaking something that you may regret about.
In your particular case, the pump appears to be fine, your issue is that the pump is not getting enough Power to create enough Pressure, though it is enough to prime the system before starting, hence why the car starts and then dies.
My theory right now is that you have a damaged wire somewhere, which is not allowing enough current to go to the pump, hence why it still manages small loads, but fails to keep the car running. The reason why I think so is because you conducted a test, where you connected 12V straight from the battery to the pump, and the car ran fine. This implies that the pump is working, and it is the issue with the 12V supply.
The theory behind the test I explained in my previous post is to actually pinpoint where exactly are you losing that 12V supply. The Headlight Bulb serves as a big fat load source, which gives you a visual of what is going on. When you add power straight from the Battery through the In-Line Fuse, you are bypassing the Fuse Box and send power directly to the Pump, which verifies that the Positive Wire going from the Circuit Opening Relay to the Pump, and the wire from the Pump to the Ground are intact and solid. When you connect the In-Line Fuse in place of the Relay, you are checking the wire that actually supplies those 12V to the Pump, which is actually where I think your issue is.
Are there any specific reasons why the junkyard is not an option? It is the only place to get parts right then and there, and a lot cheaper than at places like eBay. Besides, it is a great place to learn without the risk of breaking something that you may regret about.
05-27-21, 10:34 AM
#116
Driver
Thread Starter
The reason I said that was there is a series of steps i need to take to diagnose this issue properly so that I am not doing extra work or buying unneeded parts, The junkyards we have here are real simple you go in to the counter and tell them the part you need if they have it they go to the yard pull it then you buy .If your part is defective that you purchased and they agree then they will refund your money within thirty days of purchase.
Last edited by Brian97S; 06-01-21 at 02:08 PM.
05-27-21, 09:01 PM
#117
Pole Position
Sorry, I was a bit busy today..
The test I described above is to make sure, once and for all, whether your wiring is good or not, and then consider other options. If the wiring is good, then your only option will be to replace the pump, that said, if it would turn out to be a bad wiring, then no matter how many times you were to swap the pump, it won't help. The point is to check the wiring first, which will then reveal the way to go.
Hope this helps and best of luck!
The test I described above is to make sure, once and for all, whether your wiring is good or not, and then consider other options. If the wiring is good, then your only option will be to replace the pump, that said, if it would turn out to be a bad wiring, then no matter how many times you were to swap the pump, it won't help. The point is to check the wiring first, which will then reveal the way to go.
Hope this helps and best of luck!
05-29-21, 12:20 PM
#118
Driver
Thread Starter
Car starts and dies immediately if you spray carb cleaner in it though it will run until you quit spraying
Shorted the two vertical pins to see if the pump will engage. ....it does
put a test light across Coil pins and cranked the engine, see if it will light up...it does very brightly
Put a test light on battery first to measure illumination straight from battery then on pigtail when attempting to start test light is same ( just as bright ) as battery when attempting to start.
Put a light on battery to measure illumination then on center socket with key on result is just as bright
replaced relay
efi wire has been replaced
car still starts then immediately dies
Sprayed some starter fluid in and let it run for about 20 seconds imagined myself driving it
Shorted the two vertical pins to see if the pump will engage. ....it does
put a test light across Coil pins and cranked the engine, see if it will light up...it does very brightly
Put a test light on battery first to measure illumination straight from battery then on pigtail when attempting to start test light is same ( just as bright ) as battery when attempting to start.
Put a light on battery to measure illumination then on center socket with key on result is just as bright
replaced relay
efi wire has been replaced
car still starts then immediately dies
Sprayed some starter fluid in and let it run for about 20 seconds imagined myself driving it
Last edited by Brian97S; 05-29-21 at 03:51 PM.
05-29-21, 02:46 PM
#119
Driver
Thread Starter
when i went back and double checked the fuel pump pigtail connector i put my light across pins 4 and 5 and it did light
Last edited by Brian97S; 05-29-21 at 05:54 PM.
05-29-21, 04:48 PM
#120
Driver
Thread Starter
Ok so the only way I can put a load test on that wiring is with a a headlight? how would Lexus service department do it? what would they use?
Last edited by Brian97S; 06-01-21 at 02:09 PM.