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What killed my fuel pump(s)?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by mattski, Oct 24, 2023.

  1. mattski

    mattski Junior Member

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    After my 2005 Prius had been stored for 8 months, I got the dreaded Triangle o' Death, p3190 - 204 and p0A0F. I suspected either the 12v or traction battery, but after much misery, I determined that my fuel pump was not pumping. I found another one (and even heard it go "click" when I attached 12v to the terminals). Now, after wrestling it into the car, I got the same error codes. Applied 12v to the terminals and no sound (or fuel) from the pump.

    I'm resigned to wrestling yet another tank into place, but I wanted to check -- am I doing something to kill these fuel pumps? I wouldn't have thought 8 months of inactivity would kill a pump, nor applying 12v for a literal second. Or is this just something to expect from an 18-year-old fuel tank?
     
    #1 mattski, Oct 24, 2023
  2. Tombukt2

    Tombukt2 Senior Member

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    No I've got them sitting around here ready to go in other vehicles I've never had to change one I mean you want to be putting the right voltage to the right terminals to do your testing usually I try to make up a little harness and come from the real plug that goes to the tank and rig up something to go to the new tank so I can just push the start button and see if the pump works in unison's with the computer or whatever Toyota EFI fuel pumps are very reliable I use the same pump that's probably in our tanks in the generation 2 which is probably the same as most Corollas and Yaris I use that pump in my Aprilia Italian motorcycles because they don't fail like the piaggio Aprilia units do.
     
    #2 Tombukt2, Oct 24, 2023
  3. mr_guy_mann

    mr_guy_mann Senior Member

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    Are you sure that you are applying power and ground to the correct terminals at the fuel tank connector? Have you tested to prove that the car can supply 12V and ground at the connector when it should and that it can do so with enough current? (ie, loading the circuit with a couple amps)

    Fuel pump power goes through the white connector by the HV battery fan duct (the one that corrodes and fails when the hatch frame seams leak water).

    Have you cleaned the throttle body bore and the MAF sensor (sensing elements)?

    Posted via the PriusChat mobile app.
     
    #3 mr_guy_mann, Oct 25, 2023
  4. mattski

    mattski Junior Member

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    Greetings,mr_guy_mann --

    Yes, I've been providing 12v to the correct terminals, but straight from the battery. Is it possible it's looking for less current than I'm providing, and I'm burning something out?

    I haven't been able to test what voltage is supplied to the plug, because (I think) the Triangle o' Death shuts down the whole process. Unfortunately, I'm on an island without access to many tools, so loading the circuit with a couple of amps is not really an option currently (pun unintended).

    On the plus side, I have cleaned the MAF and throttle body, and they seem to check out OK. I pulled the fuel rail and confirmed that no gas is being delivered to the injectors, so the lack of sound from the fuel pump seems to be the most likely culprit. Before I drive four hours tomorrow to get another fuel tank, I will test the connector you mention. Should it provide 12v all the time, or just when the engine is being cranked?

    Thanks so much for the help. This combination of error codes is really difficult to ferret out.
     
    #4 mattski, Oct 26, 2023
  5. mr_guy_mann

    mr_guy_mann Senior Member

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    Just want to make sure you're at the correct wires. The (large) black is 12V+ and the white-black is (gnd - ).

    What is the resistance across those two terminals on the tank? It's not a great test but I would expect something less than a couple ohms.

    The fuel pump gets 12V power from the "circuit opening relay", which appears to be internal to the underhood fusebox. The ECM turns the relay on when it wants the ICE to start & run.

    This would be "easy" to test if you have a scantool ghat has bidirectional controls (such as Techstream, or two of the tools in my review thread). Just go into the ECM menu and select (turn on fuel pump) test.

    Unless you have a means to recharge the HV battery, I would be careful about attempting to start the ICE too many times. Not sure what to suggest about that.

    If you supply 12V to the correct terminals on the tank, then you can't "hurt" the pump. Either it draws current and operates, or is high resistance (open circuit) and doesn't operate. (it's possibly seized and would pull lots of current - that would spark connections, melt things, & I have never seen a fuel pump do that).

    You could have two "bad" pumps, but I just don't see pump failures like I used to 20 years ago. I have yet to see one go out on a Toyota hybrid. So possible, but unlikely. DSC_6280_1_1.JPG

    Posted via the PriusChat mobile app.
     
    #5 mr_guy_mann, Oct 27, 2023
  6. Doug McC

    Doug McC Active Member

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    I’m not clear on how you are supplying power to the pump. If you are using the vehicle’s wiring, is it possible that the Emergency Shut Off System has been activated (shutting off power to the pump)?
     
    #6 Doug McC, Oct 27, 2023
  7. mattski

    mattski Junior Member

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    Thanks to all for the suggestions. I've been applying 12v right at the fuel pump plug, as illustrated in mr_mann's post. Silly me, although I've also been testing using the Techstream fuel pump command, it didn't occur to me to test the voltage from that. It _is_ 12v (or 11.8, which may be part of my problem).

    I just obtained yet another used fuel tank that has been tested, so I'm hopeful. (The seller also mentioned that he has experienced a few fuel pumps that have frozen up after being stored for a year, which is kinda our situation.)

    As mr_mann suggests, I'm pretty sure I've drained my HV battery by foolishly trying to start it too often, but will recharge it one module at a time. One concern -- even when I replaced and/or shifted modules around, the voltage in slot 14 is significantly lower than the other slots --13.3 vs 14.4ish. Any chance there's something about that last position that might be suspect?

    Thanks again!
     
    #7 mattski, Oct 27, 2023
  8. mr_guy_mann

    mr_guy_mann Senior Member

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    Yep. 1.0 to 1.5V lower than others means that a cell in that module has failed.

    Good luck with battery pack.

    Posted via the PriusChat mobile app.
     
    #8 mr_guy_mann, Oct 27, 2023
  9. TMR-JWAP

    TMR-JWAP Senior Member

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    If your blocks are 14.4 volts, you're on the edge of depletion. When you initially press the power button, will the car shut the main relays and go to ready mode? Shortly after that, it should attempt to start the ICE. If the car won't even get to READY, I would say your problem is there. Maybe HV battery was depleted before the second fuel tank was installed? Even a depleted module will drift back up to 7.2+ volts when it sits for a while, so that may be why you're seeing 14.4 volts on the blocks. Put it under the slightest load and it would drop like a rock and the main relays would probably not stay closed.
     
    #9 TMR-JWAP, Oct 28, 2023
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