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post #1 of 10 (permalink) Old 05-08-2019, 11:30 PM Thread Starter
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Burning out fuel pumps - possible causes?

I have a 2002 RAV4 and it wasn't starting when I got it. I found the fuel pressure was bad so I installed a new pump. I could visually see some flow but when connected to the system it wouldn't put out 30+ psi only about 5psi. So I took a used fuel pump off another car and it ran great for about 1 week.


Now this fuel pump is fried (12V on the terminals and nothing). So that's 2 pumps that went bad and one that might have been faulty out of the box.


  • Flushed output lines twice
  • Noticed there's some suction when the cap is opened or when the pump assembly is lifted out
As far as i can tell there seems to be no other inline filters, it just goes from the pump up to the regulator on the fuel rail.


Am I missing something? What else might be causing these pumps to fail (they have new filters and clean fuel)?


Thanks!
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post #2 of 10 (permalink) Old 05-09-2019, 07:36 AM
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Does removing the fuel cap make any difference?

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It's the pedal (or the handgrip) on the right!!


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post #3 of 10 (permalink) Old 05-10-2019, 12:25 PM
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It is possible to have 12V at the pump without having enough amperage (bad ground or power, or faulty wiring).

2001 with 2.4 swap + RAV4.1 transmission (4.93 final drive ratio), RAV4.1 locking center differential, Lexus RX300 limited slip rear diff , Celica GT4 stage 1 SPEC clutch kit, 3" lift kit, Old Man Emu coil-springs, sway-bars delete and BFG MT KM2 235/70/16.
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post #4 of 10 (permalink) Old 05-11-2019, 12:14 PM
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-- It appears a "fuel pulsation damper" is in the fuel line for your Rav4. See the "parts location" diagram at Toyota RAV4 Service Manual: Fuel system - 2Az-fe fuel . I wonder if your Rav4's pulsation damper is blocked. My Haynes manual has instructions for its replacement.

-- Fuel pumps can overheat and not work, but when they cool down, they may resume working. You can bench test your old fuel pump. Connect say a 6 volt battery to it. When connecting, get the polarity correct, of course. Connect the pump for half a second outside the fuel tank to give you an idea of whether the pump has truly failed. Do not run more than half a second, since ordinarily, fuel would run through it and keep it cool. If your old pumps still run for that half second, I would suspect blockage somewhere in the fuel lines.

-- Causes of overheating may be a blocked discharge line (e.g. a blocked pulsation damper or discharge line fuel filter?) or inadequate head at the suction. E.g. a low fuel tank or possibly the fuel strainer (or inlet filter) located at the pump's suction being way dirty may cause a low head at the suction. But you say the inlet filter is clean.

-- eBay is showing fuel filters for the 2001-2005 Rav4 that look like they go outside the fuel tank. I see conflicting information on the point, though.

1998 Rav4, Manual Transmission, 2WD, JDM engine with 85k miles in early 2019
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post #5 of 10 (permalink) Old 05-11-2019, 07:36 PM
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Suction is normal if you didnt release the pressure from the system other ways before opening it.
Did you replace both filters in the tank, or only the bottom one? There isnt any filters outside the tank on the second gen, only on the 1st gen.
Have you checked that all the o-rings and electrical connections are in good shape on the unit?
If the o-ring on the output of the filter is shoot the pump will pump fuel back into the tank and the pressure regulator will not do its job.
On the output of the pump there is also a thick o-ring, you remember to transfer it to the new filter?
Any engine codes? Lean?



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post #6 of 10 (permalink) Old 05-14-2019, 09:07 PM Thread Starter
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Thanks for all the ideas.


  • No difference with/without cap, or with the fuel pump body loose from the tank.
  • Both filters? I have a gen 2 (2002 1az-fe) and I only see the single screen at the bottom of the pump. Is there something else? I've traced the fuel lines and they seem to go from the pump directly to the fuel rail regulator with no other filters.
  • Odd thing is the pumps are not hot, but when I applied 12V they didn't run (polarity is correct). Today I got a new pump and pulled the old one out and retested it and it worked fine. So I roughly compared it to the new pump and they seemed to be spinning about the same amount and torque at startup (I don't have a fuel pressure gauge -- but can borrow one)
  • No engine codes.
  • No start unless I spray starting fluid into the air intake as the engine seems to not be getting any fuel.
Some new things:

  • I connected the pump to the fuel line and I break the fuel line before the fuel rail and regulator. Then I forced the pump on using ODBII software. The fuel flows out of the line going into the regulator fine. However, if I reconnect the line, run the pump for a bit and then disconnect the fuel line again there seems to be nothing pressurized. Fuel doesn't even drip out.
  • I can't find any fuel leaks.
  • When forcing the pump on with ODBII it cycles on and off every 5 seconds or so. Is that normal for the ECU test mode?
  • I suspect the pump isn't reaching pressure or holding pressure. Could this be the job of the "fuel pulsation damper"?
  • (edit) After reading about the pulsation damper, I realize I have swapped that out from another car that was running fine. I don't know if either of them were faulty but neither seemed to change anything.


Let me know if you guys have any ideas because I don't know what's going on. I spent a couple weekends going through the fuel system and the engine until I realized the fuel pressure wasn't right. After swapping the fuel pump (a new one with an old one from another car) it was pressurizing and working again. I assumed the new pump was faulty and perhaps my second new pump is faulty too, but I suspect there's something else going on.


I'll try looking into the pulsation damper. There is also some kind of regulator in the pump assembly too. Any other ideas?
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post #7 of 10 (permalink) Old 05-15-2019, 12:11 PM
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Quote:
Originally Posted by EricA View Post
I connected the pump to the fuel line and I break the fuel line before the fuel rail and regulator. Then I forced the pump on using ODBII software. The fuel flows out of the line going into the regulator fine. However, if I reconnect the line, run the pump for a bit and then disconnect the fuel line again there seems to be nothing pressurized. Fuel doesn't even drip out.
With all the other troubleshooting you did, what you wrote above gets my attention. Comments:

-- It seems like your fuel system parts work okay when there is no "back pressure." "Back pressure" is the pressure on the pump discharge due to restrictions yada in the pipes downstream of the pump. When you re-connect everything, the back pressure goes up and something gets thrown off. I am thinking a pressure regulator is not working right. Pressure regulators typically have little diaphragms in them that can weaken with time or develop a hole.

-- The fuel pressure regulator in the tank (a part of the fuel pump module assembly) is Toyota part number 23020-28010. Google on the part number, and photos of the regulator will come up. The in-tank fuel pressure regulator re-circulates part of the fuel pump discharge. If the regulator is not working correctly, or is erratic, then I think it might give the symptoms above. The regulator seems to rarely fail. Still, I might try installing a used in-tank fuel pressure regulator from a salvage yard.

-- I would consider replacing whatever "fuel pressure regulator" you found at the fuel rail. I cannot find a Toyota part number for this. I cannot find a diagram showing this. I am not sure there is a fuel pressure regulator outside the fuel tank. Is there a part number stamped on the one you found?

-- I think there is a fuel pressure sensor at the rail. I see reports of it setting off code p0191 on OBD2 vehicles, including Rav4.2s. Maybe check this as well.

-- Watch for O-rings. My Rav4.1's in tank fuel pressure regulator involves a few. If the O-rings are worn, then the fuel system may not be holding pressure.

-- If you can post photos pointing to the pulsation damper, fuel rail and "fuel pressure regulator"(which you say is outside the fuel tank), this might be helpful. I am not having much luck finding a good fuel system diagram for the Rav4.2.


Less likely causes of the no fuel situation:

-- There is a second fuel filter. It is a part of the 'fuel pump module assembly' that you have removed from the fuel tank and re-installed several times now. Google for toyota part number 23300-28040 (formerly, 23300-28030), and you will see photos of this second filter. It is typically called the "fuel filter assembly" and similar. This filter is not shown well at U. S. Toyota parts site diagrams. This site has a superior exploded view of the fuel pump module, showing way more detail: http://www.jp-carparts.com/toyota/pa...ype=7&fig=7701 . (For the 1996-2000 Rav4, U. S. part sites are similarly terrible when it comes to a similar, secondary fuel filter located in the fuel tank. I think the point is, Toyota feels one should 'ordinarily' never have to replace these secondary fuel filters. But extraordinary conditions do arise on our old Ravs. I found my Rav4.1 secondary filter filthy, due to a rusty fuel tank.) This second fuel filter is currently about $26 plus s/h at McGeorge toyota parts. McGeorge confirms this second filter is used on the generation 2 Ravs. EBay has this filter as well. For what it is worth, my 2003 Honda Civic had a similar setup: One fuel filter (strainer) at the pump suction, and a second fuel filter assembly at the discharge or in the recirc line, both in the fuel tank.

-- Have you ever changed out the entire fuel pump module assembly with one from a salvage yard? This would include the fuel pump, in-tank fuel pressure regulator, suction filter (a.k.a. strainer or sock), and the secondary fuel filter assembly, all built into the fuel pump module assembly?

-- For the interested reader, an aftermarket part number for the entire fuel pump module that leads to helpful photos on the net is Spectra SP9038M .

-- Dunno about OBD2 and the cycling on and off of the pump. I tend to think the cycling points to something that is broken.

1998 Rav4, Manual Transmission, 2WD, JDM engine with 85k miles in early 2019
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post #8 of 10 (permalink) Old 05-15-2019, 03:03 PM Thread Starter
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I do have another full used pump assembly and it's what drove me to suspect the pump needed to be replaced (which it did -- fried). I swapped it out some time ago but the old pump in it seemed to burn out again. So I have 2 new pumps and 2 assemblies (one of which is still suspect).


So I'll try swapping some things around. I also borrowed a fuel pressure gauge that I can put on the rail while I'm testing things. I'll report back what I find after reading all your great information about the various parts of the fuel system.



Quote:
-- I would consider replacing whatever "fuel pressure regulator" you found at the fuel rail. I cannot find a Toyota part number for this. I cannot find a diagram showing this. I am not sure there is a fuel pressure regulator outside the fuel tank. Is there a part number stamped on the one you found?

-- If you can post photos pointing to the pulsation damper, fuel rail and "fuel pressure regulator"(which you say is outside the fuel tank), this might be helpful. I am not having much luck finding a good fuel system diagram for the Rav4.2.
My bad. I keep calling the "Fuel pressure pulsation dampener assembly" a regulator. It's the one on the rail P/N 23270-28021. The one inside the tank could be a suspect too along with the filter part you mentioned. I'll look much closer at everything and try swapping some things out. I did swap the dampener from another running car and that's the one that is on there. And the car was running for a couple weeks before this fuel problem reappeared with the failed fuel pressure. Having the fuel pressure gauge should help remove some guess work.



I did replace the o-rings on the injectors, but I did not do anything with the pump assembly.
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post #9 of 10 (permalink) Old 05-15-2019, 05:25 PM
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Was this 2002 Rav4 sitting, undriven, for a number of months? When was the last time it was run to near empty and then filled up?

I wonder if you have a fuel tank full of rust-laden gasoline. How dirty did the fuel pump's suction strainer (filter) look the first time you replaced the fuel pump? How about for subsequent replacements? Maybe scoop out a glass full of gasoline and see how dirty it looks. But even this does not look promising, since you have been swapping what are likely good used assemblies in and out. It would take awhile for the in-tank parts to foul with rust and cause a no-start. Unless maybe the fuel tank is crazy full of rust?

Are you keeping the battery well-charged? A low battery will aggravate diagnosis by causing a hard-start condition -- not enough power to the starter to turn over the engine with enough force et cetera.

1998 Rav4, Manual Transmission, 2WD, JDM engine with 85k miles in early 2019
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post #10 of 10 (permalink) Old 05-15-2019, 11:32 PM Thread Starter
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When I pulled the pump assembly out I could see about 90% of the tank. It was clean and rust free but sitting for a long time, so I drained it and cleaned what little black flakes were in there. The screens were clean and I flushed all the lines just in case.


I did find that there must be something wrong with that pump assembly though and not the pump. With the fuel pressure gauge it would only read about 3 psi. I swapped the assembly out and got a solid 50psi and it held pressure. So either the integrated filter, regulator or an o-ring was leaking. Once I got a setup that was working, I had to keep moving forward rather than debug the defective assembly. I'll get to it soon, but at least I know roughly what to look for when I try to get the second pump assembly working.


For now I have at least one up and running and it's on to fixing the transmission.



Thanks for all the help, especially you Elle_Rav4, who had a lot of good info that I'll need to reference when I go to debug the other pump.
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