Anyone had this happen? I replaced my fuel pump pre-emptively with an Aisin model and now my gauge is all over the place. I know Aisin is generally regarded as a higher-tier aftermarket so I'm surprised to see a failure in a brand new part like this. Wondering if there is anything else to check before I drop my tank again.
Brand new fuel pump, bad sender
- Thread starter Cezar
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Runnin on E
Member
What does a new pump have to do with your fuel gauge?
What's your favorite flavor of crayons?
Anyway, I went and pulled the back carpet out to do some basic checks. Gauge tests fine for full and empty as expected. The SM for some reason doesn't list resistance checks for the connector on the top of the fuel pump assembly, just on the internal float connector itself. Interestingly enough, checking resistance on the assembly connector just reads 0L. Must be some circuit that stands between the main harness and internal connector.
So that's all the checks I can do so whatever the cause, it's going to necessitate a new pump assembly and dropping the tank.
Runnin on E
Member
So it really has nothing to do with the gauge. What you are trying to say (not very clearly) is the CONNECTOR at the fuel tank is the problem because you disconnected it to change the pump. It is spelled GFY.
You must be a hit at parties.
Anyway, been running the tank down so I can drop it. Went ahead and bought a transfer pump and I've got a couple empty cans so I'll kick off this project in the morning. After shopping around my options for new pumps is really bad. Everything is a knock off or nearly a thousand dollars. On top of that, I noticed today that not only is the new sender bad, the new pump is loud enough that I can hear it outside the car from several feet away.
Does not bode well.
So, I went ahead and ordered a new OEM Denso pump and filter as well as a new sender. I'll just rebuild the OEM pump assembly (and carefully test all function before putting everything back together). I don't want to roll the dice on another Aisin since this unit has two separate and unrelated issues.
Got the tank out this morning. Funny how much easier a job is when you have done it before. Also found my missing 12mm socket which was hanging out on an undertray bolt.
BTW tip for getting the tank out when its got a fair bit of gas in it; There is a round spot for a jack under the rear half of the tank where the pump sits. Position jack there, disconnect everything, then put a cardboard box under the front. Using hands and feet, drop the tank with the jack while slowly crushing the cardboard box to keep it level as it comes down. You could do this with 10+ gallons in there single-handed.
I had bought a transfer pump from amazon. Wouldn't fit in any of the holes so I went to autozone and bought a manual pump, springing for the premium brass version. It instantly leaked all over me and I ended up using it just as a siphon starter. I then dropped the tank and used the first transfer pump to fully empty the tank...........which also leaked all over me.
This is the quality of everything these days.
Currently awaiting new Denso pump to arrive for reinstall...
BTW tip for getting the tank out when its got a fair bit of gas in it; There is a round spot for a jack under the rear half of the tank where the pump sits. Position jack there, disconnect everything, then put a cardboard box under the front. Using hands and feet, drop the tank with the jack while slowly crushing the cardboard box to keep it level as it comes down. You could do this with 10+ gallons in there single-handed.
I had bought a transfer pump from amazon. Wouldn't fit in any of the holes so I went to autozone and bought a manual pump, springing for the premium brass version. It instantly leaked all over me and I ended up using it just as a siphon starter. I then dropped the tank and used the first transfer pump to fully empty the tank...........which also leaked all over me.
This is the quality of everything these days.
Currently awaiting new Denso pump to arrive for reinstall...
Hey I had problems with my fuel gauge reading improperly last year, 04 V6. I replaced the gas cap and interestingly, it corrected the problem until the past week. So I thought it might be the fuel sender, but when I went to my mechanic (very honest), said he'd hate to see me replace the sender and the fuel pump if it's not the cause of improper fuel gauge reading ... so it got me thinking. Can you tell me what could be other possible causes of an incorrect gauge reading? TIA!
Got the tank back in. Made sure to test the sender in its full range BEFORE putting the car back together. Should have done that last time!
Replacing the pump on the assembly was annoying but simple. Just pop the bottom off and slide the unit apart. Then there are 2 notches you can fit 2 flatheads in to pry tabs off the motor. There is no way to get leverage on the motor so what I did was put a large vise grip onto the motor body and then use a very large flathead to pry the motor out of its hole, which worked well.
New Denso pump is vastly quieter than the Aisin pump. I stuck my ear to the access panel in the backseat and all I could hear is the fuel splashing back into the tank from the return. Couldn't even hear the motor with my ear right on it.
Replacing the pump on the assembly was annoying but simple. Just pop the bottom off and slide the unit apart. Then there are 2 notches you can fit 2 flatheads in to pry tabs off the motor. There is no way to get leverage on the motor so what I did was put a large vise grip onto the motor body and then use a very large flathead to pry the motor out of its hole, which worked well.
New Denso pump is vastly quieter than the Aisin pump. I stuck my ear to the access panel in the backseat and all I could hear is the fuel splashing back into the tank from the return. Couldn't even hear the motor with my ear right on it.
Maybe. The packaging looked like other Aisan packaging, instructions too. The pump assy looked a little plain though. Really, impossible to say without another unit to compare with.
FML.
This is now the first time in my entire life I will have to do a car repair 3 times in a row.
The NEW OEM DENSO pump is no good. Every start is a hard start and it's sluggish and doesn't want to rev.
I'm _absoluely_ certain I did not introduce a clog or anything similar during the repair. The fuel lines are all clipped in properly.
Driving the car yesterday it was fine. Today, symptoms like crazy.
Bout to lose it. This is a MISERABLE repair.
This is now the first time in my entire life I will have to do a car repair 3 times in a row.
The NEW OEM DENSO pump is no good. Every start is a hard start and it's sluggish and doesn't want to rev.
I'm _absoluely_ certain I did not introduce a clog or anything similar during the repair. The fuel lines are all clipped in properly.
Driving the car yesterday it was fine. Today, symptoms like crazy.
Bout to lose it. This is a MISERABLE repair.
Woof. Just did a few miles to pick the kid up from school. This went from working great, to hard start and mild shudder, to totally undriveable in ~20 miles since the pump was installed. CEL is on with the expected codes and the truck is unable to maintain speed on a moderate hill.
What on earth.
What on earth.
AuSeeker
Elite Member
Starting to think this is user error. I was looking at the original denso pump and there is a bung / spacer that goes on the pump outlet that I neglected to install. My working theory at the moment is that this allowed the pump to jump loose and so its spraying internally inside the pump assembly and only a certain amount of fuel is making it into the lines. I show 15psi on a pressure tester which backs up that theory.
Dang.
I'll tear it apart in the morning and find out.
Dang.
I'll tear it apart in the morning and find out.
Well, the saga continues. I redid the entire job this morning, confirmed that the little bung piece was not where it should have been, buttoned everything up, and
(Spec is 41psi)
So I now get to do the entire job a fourth time! Yay!
EDIT: What are the odds that this amazon gauge is bad? My PSI did in fact double after this repair, it's just still below spec ACCORDING TO THE GAUGE.
(Spec is 41psi)
So I now get to do the entire job a fourth time! Yay!
EDIT: What are the odds that this amazon gauge is bad? My PSI did in fact double after this repair, it's just still below spec ACCORDING TO THE GAUGE.
AuSeeker
Elite Member
Well, the saga continues. I redid the entire job this morning, confirmed that the little bung piece was not where it should have been, buttoned everything up, and
(Spec is 41psi)
So I now get to do the entire job a fourth time! Yay!
EDIT: What are the odds that this amazon gauge is bad? My PSI did in fact double after this repair, it's just still below spec ACCORDING TO THE GAUGE.
How does it run now, still triggering the CEL/codes?
As far as the gauge, these days anything is possible coming from Amazon!
Narrator: in fact the amazon gauge was bad.
I decided before tearing it apart to go try another gauge. Borrowed the Autozone fuel pressure gauge kit. It had basically zero fittings in it so what I did was unscrew the gauge from my kit and swapped the physical gauges.
Started the car up, gauge instantly hit 41psi on the nose.
Put everything back together, went for a drive. Completely fine.
So this morning I was cleaning up after this project, had about 4 gallons I had decanted out of the 4runner so I went ahead and poured the can back into the tank. I checked the fuel gauge beforehand and it was 1mm below a quarter tank. Poured the gas can in and re-checked, zero movement in the needle. FML.
Decided to go fill it up on the off chance the float just needed to be jostled loose. As I was driving I hit a couple bumps and it seemed to move upward about a mm. Got a full tank of gas and it took 14 gallons and when I restarted the car it showed a full tank.
So 2 possible working theories at the moment:
- When I added gas it was deposited into a section of the tank where the lateral volume expands drastically. The sender sensor is linear but the tank capacity is not
- Driving and filling the tank jostled the float free from however it was binding.
(bonus third theory) - the amazon sender I bought is a piece of crap.
I'll have to drive it a week or two and see. I'm not doing this job a fourth time so if I have to replace the sender the sheet metal is getting cut.
And on the amazon thing; I'm going to have to slow down my amazon purchases. Just in this one project I got:
- A bad fuel pump and sender
- A leaking fuel transfer pump
- A totally defective fuel pressure gauge
And this mirrors an overall trend with amazon products. It's never been as bad as it is lately and I'm returning more stuff than I am keeping.
On a positive note the truck hit all readiness monitors this morning.
Decided to go fill it up on the off chance the float just needed to be jostled loose. As I was driving I hit a couple bumps and it seemed to move upward about a mm. Got a full tank of gas and it took 14 gallons and when I restarted the car it showed a full tank.
So 2 possible working theories at the moment:
- When I added gas it was deposited into a section of the tank where the lateral volume expands drastically. The sender sensor is linear but the tank capacity is not
- Driving and filling the tank jostled the float free from however it was binding.
(bonus third theory) - the amazon sender I bought is a piece of crap.
I'll have to drive it a week or two and see. I'm not doing this job a fourth time so if I have to replace the sender the sheet metal is getting cut.
And on the amazon thing; I'm going to have to slow down my amazon purchases. Just in this one project I got:
- A bad fuel pump and sender
- A leaking fuel transfer pump
- A totally defective fuel pressure gauge
And this mirrors an overall trend with amazon products. It's never been as bad as it is lately and I'm returning more stuff than I am keeping.
On a positive note the truck hit all readiness monitors this morning.
gomiami
Member
I would guess #2 or #3. I never buy auto parts off Amazon anymore. Bought a speed sensor and a power window switch assembly (at different times) off Amazon and the speed sensor was defective, while the switch was incorrect despite it being an exact match for the OEM part number.
Neither was a time-consuming repair like yours but it was a pain to convince Amazon that an installed electrical component deserves a refund, especially since the seller was a 3rd Party who initially refused. Had to escalate it with Amazon to get my money back.
Now, I just buy stuff from the handful of dealerships that sell online and offer good pricing on OEM stuff or, if the factory price is outrageous/it's discontinued, the local parts store.
Saves the headache and the time for a little bit more money...a worthy trade-off IMHO.
My biggest complaint with the online dealers is that EVERY SINGLE ONE OF THEM cannot do overnight shipping.
I simply cannot get OEM Toyota parts, from any official source, overnight shipped. It's infuriating coming from the BMW world. Absolute night and day difference, and one of the worst parts of owning a Toyota. The parts fische's are garbage too.
I simply cannot get OEM Toyota parts, from any official source, overnight shipped. It's infuriating coming from the BMW world. Absolute night and day difference, and one of the worst parts of owning a Toyota. The parts fische's are garbage too.
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