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Edward
Edward, ASE Certified Technician
Category: Toyota
Satisfied Customers: 3153
Experience:  I have over 20 years experience in the automotive service industry.
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My car is a 2002 Toyota Avalon with about 250,000 miles. I

Customer Question

My car is a 2002 Toyota Avalon with about 250,000 miles. I replaced the fuel pump about a year ago, and the replacement lasted for about a week before it gave out too. I assumed it was defective and replaced it again. Since then, the car has been hard to start unless it is warm and has been running for about 15 minutes. I replaced the IAC valve at about the same time and have cleaned it several times. The fuel pump gave out again recently and when I tested it with a multimeter, I found neither of the wires leading to the pump are getting power when the ignition is on. When i try to start it the voltage on one wire jumps from zero to 8.5, then up to 11 or 12 for about a second when i release the key, then back down to zero. The fuel pump relay and fuses are all good. I checked the fuel pump and it isn't pumping even when it gets power so i am replacing it, but what could cause the voltage differences, and could that be causing the hard start? No codes or lights are on
Submitted: 2 months ago.
Category: Toyota
Expert:  Edward replied 2 months ago.

Hello, and thanks for your question. My name is ***** ***** I will do all I can to help.

Expert:  Edward replied 2 months ago.

What kind of fuel pump are you using ? Airtex or Carter or Duralast by chance? I would recommend a Delphi or Bosch or Denso on fuel pumps, The system is set to work where the fuel pump only gets power when you first turn the key ON, (a 2-3 second prime) then when cranking you should get battery voltage, then when running, you should get a constant system voltage of around 14 volts.

The pump does NOT run the entire time the key is ON. So if you turn the key ON, the pump will not continuously run. Only when the engine computer see's a signal from the crank sensor does it ground the fuel pump relay to allow power to the fuel pump.

Customer: replied 2 months ago.
the pump says highflow on the side, im guessing thats the brand. I tested the pump and even when it is getting power, its not pumping so I am definitely replacing that. Im not getting power for the 2-3 seconds when I first turn the key on to on, only when I hold the key to start.
Expert:  Edward replied 2 months ago.

You will have to check for that prime power with a test light, as a digital volt meter isn't quick enough to show it really. You should get a bit of a prime though with key on. I do not trust cheap fuel pumps. I have had my fill of Airtex and Duralast pumps. I'm not familiar with HighFlow, but I'm skeptical if it's not a name brand like Bosch, Denso, or Delphi, even Carter is ok. It's possible you are losing fuel pressure when you turn the engine off. Try cycling the key a couple of times then starting the engine.

Expert:  Edward replied 2 months ago.

Put a good quality fuel pump in it. Denso, Delphi, or Bosch, You won't have these fuel pump problems in my opinion. make sure your getting a good solid 14 volts to the pump when it's running.

Customer: replied 2 months ago.
Do you have any idea what could be causing the hard start the? I replaced the IAC valve at the same time I replaced the pump a year ago and it has been hard to start since then.
Expert:  Edward replied 2 months ago.

It just spins and spins for a while correct? then eventually fires up?

Customer: replied 2 months ago.
ive tried cleaning the IAC valve several times it hasnt helped. in my experience pumping the gas helped when I was having IAC issues but it does not when its hard starting
Customer: replied 2 months ago.
It does fire up after 5-10 seconds, less if the engine is warm
Expert:  Edward replied 2 months ago.

I believe your losing fuel pressure with these cheap pumps honestly. The pump has a check valve in it. it is supposed to HOLD pressure when you turn the key OFF, when pressure bleeds back off after it sits a while, (usually either through dirty fuel injectors or a leaky check valve in the pump) you have to spin the pump for a while to build pressure back up, if when it fired up it smoked black a bit, and ran rich, I would say the injectors were leaking down and bleeding off some gas into the engine, but if it didn't fire up and run rich for a few seconds, I would say fuel pressure is leaking down, try this, cycle the key a few times before starting, this builds up fuel pressure before you turn the key to the START position. I'm thinking a good quality pump will help that problem too. Run some techron through the injectors, a good fuel injector cleaner in case they are leaking down.

Customer: replied 2 months ago.
I understand but even though Im not getting power when the key is on? my voltmeter reads to a hundreth of a volt and it said 0.00 when the key was in the on position what would a test light tell me that the volt meter doesnt?
Expert:  Edward replied 2 months ago.

the pump does not get power the whole time the key is on. The system was not designed so the fuel pump would run constantly when the key is on.

Expert:  Edward replied 2 months ago.

Now it does run constantly when the engine is running of course. It will only get a very short prime of voltage when you first cut the key on. If you probe that wire with a test light, you'll see the light come on just for a very short time, (sometimes just 1 to 2 seconds) before the light goes off with the key on.

Customer: replied 2 months ago.
I understand but I watched the voltmeter while my dad tried to start the car and I am not getting power even for those few seconds
Expert:  Edward replied 2 months ago.

I follow you, they generally take longer to measure than duration of power your getting in my opinion. I've always checked that with a 12 volt test light, Now cranking what do you get on your volt meter? should be battery voltage, but battery voltage goes down some with the starter motor drawing a good bit of voltage,

Customer: replied 2 months ago.
I just went and put a test light on it and the light doesnt come on when the key is in the on position. when i crank the engine the light flashes with the engine turning over, then stays on for a second after I release the key
Expert:  Edward replied 2 months ago.

Alright, that is interesting. it shouldn't pulse like that, should light up for 2 seconds or so on initial prime with key ON. Here is the diagram.

Customer: replied 2 months ago.
I know it should light up for a sec when I turn the key to "on" but it isnt. It only lights up when i am holding the key and the engine is turning over. Do you know what could be preventing it from getting power when it should be getting primed?
Customer: replied 2 months ago.
I appreciate the diagram but what electrifys the pump during those 2 seconds? is it the EFI relay or the IAC controller or something?
Expert:  Edward replied 2 months ago.

There is an EFI relay, and there is an circuit opening relay in the wiring diagram. I suspect something is causing an issue there. the Engine computer grounds the circuit opening relay so it's possible it may be something there pulsing. Turn the key to the ON position and check a fuel injector wire BLACK and WHITE wire with key ON, tell me if that pulses too.

Expert:  Edward replied 2 months ago.

The engine computer does. or is supposed to. The engine computer grounds the circuit opening relay which puts power to the pump.

Expert:  Edward replied 2 months ago.

Do you have an OBD II type scan tool you could check to see if any codes were stored in the ECM with?

Customer: replied 2 months ago.
yeah I looked and its not throwing any codes. Where is the circuit opening relay located on the car?
Customer: replied 2 months ago.
theres an unmarked relay behind a trim panel in the drivers footwell is that it?
Expert:  Edward replied 2 months ago.

let me opt out and let another expert assist, I m not showing it's exact location in my references. Thank you