Fuel Pump Assembly Question - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

amanzoli · 01-07-2018, 11:58 PM

I recently removed my fuel pump assembly to siphon out my tank. After re-installing and filling tank back up with 10 gallons of fuel, my gauge only reads 1/2 full. Does anyone know if this has to do with how the tank transfers the fuel from one side to the other or does it have to do more with how I re-installed the assembly unit? Could there have been a possibility of the float getting moved around or something? I know I had to push down and twist the assembly a bit when I re-installed it. Anyone else run into this issue. Any help would be appreciated.

Mr.ac · 01-08-2018, 03:09 AM

Yep. Done screwed it. No worrries. It happens a lot when you mess with fuel pumps unknowingly.

Either buy new parts or try it again. Might want to re read the repair manual again, or take it to a shop.

humfrz · 01-08-2018, 01:25 PM

I'll vote for the "take it out and try again" approach.

humfrz

Sapphireho · 01-08-2018, 02:27 PM

Also note that there are many non-reusable parts when re-assembling.

Grady · 01-08-2018, 02:35 PM

Quote:

Originally Posted by Sapphireho

Also note that there are many non-reusable parts when re-assembling.

Oh shit I must be driving a death trap now, I did not replace any of those components when I installed my pump and flapper valve.

amanzoli · 01-08-2018, 07:14 PM

I did not repair anything, I just pulled out the assembly to place a siphon tube in the tank, so I could siphon the fuel. Perhaps the float got stuck on on something. I don't know, I may have to try to reposition it. Problem is, it's such a hassle to get the assembly in right each time.

davidsn_670 · 01-08-2018, 07:28 PM

To rule out a faulty fuel level sensor, you can use a multimeter set to ohm's and check continuity while slowly sweeping the float up and down. See if there is a break in continuity. But sounds like you may have twisted it causing the terminals to not fully contact each other. Or pull the assembly out and see if the gauge reads full when you manually move the float.

humfrz · 01-08-2018, 10:50 PM

Quote:

Originally Posted by Grady

Oh shit I must be driving a death trap now, I did not replace any of those components when I installed my pump and flapper valve.

Too bad, Grady ...... let me know when the part out starts ...... if there is anything left ......

humfrz

humfrz · 01-08-2018, 10:52 PM

Quote:

Originally Posted by amanzoli

I recently removed my fuel pump assembly to siphon out my tank. .........

Just curious, why did you want to siphon out your tank ..... ??

humfrz

Ultramaroon · 01-08-2018, 11:03 PM

There's something weird about how the fuel level sensing works. Many people here have had issues with the not going to full because they were in the habit of topping off instead of running below a quarter tank.

I won't pretend to understand why but it's real.

If you're pretty sure you got it together ok, maybe try just driving it empty and see if the system sorts itself out.

humfrz · 01-08-2018, 11:17 PM

Quote:

Originally Posted by Ultramaroon

There's something weird about how the fuel level sensing works. Many people here have had issues with the not going to full because they were in the habit of topping off instead of running below a quarter tank.

I won't pretend to understand why but it's real.

If you're pretty sure you got it together ok, maybe try just driving it empty and see if the system sorts itself out.

Now, how in the hell is he going to do THAT .....??.

humfrz

Ultramaroon · 01-08-2018, 11:55 PM

Quote:

Originally Posted by humfrz

Now, how in the hell is he going to do THAT .....??.

humfrz

Well, until the idiot light comes on but I imagine you see those all the time.

humfrz · 01-09-2018, 12:25 AM

Quote:

Originally Posted by Ultramaroon

Well, until the idiot light comes on but I imagine you see those all the time.

Well, ya ........ there is the arrow one that points to the left ...... it pretty much blinks until I turn, then the one that points to the right starts blinking and blinks till mrs humfrz says something ......

Stupid lights ........ back-in-the-day ....... I never had a problem remembering to bring my arm back into the car ......

humfrz

Sarlacc · 01-09-2018, 02:57 AM

Quote:

Originally Posted by Ultramaroon

There's something weird about how the fuel level sensing works. Many people here have had issues with the not going to full because they were in the habit of topping off instead of running below a quarter tank.

I won't pretend to understand why but it's real.

If you're pretty sure you got it together ok, maybe try just driving it empty and see if the system sorts itself out.

That's what I'd do.

Quote:

Originally Posted by humfrz

Now, how in the hell is he going to do THAT .....??.

humfrz

Drive until it stalls?

Quote:

Originally Posted by Ultramaroon

Well, until the idiot light comes on but I imagine you see those all the time.

You mean the low fuel warning light? That's very far from empty, you know.
In my estimate (and in my car) it comes on when there's between 10 and 12 liters left in the tank. That's 20% to 24% of a 50 liter tank. The light is useless.
I've driven more than 80km with that light on and still only managed to cram 44 liters in there.

01-07-2018, 11:58 PM	#1
amanzoli Member Join Date: Apr 2016 Drives: 2015 Subaru BRZ series.blue Location: Northern California Posts: 24 Thanks: 2 Thanked 6 Times in 6 Posts Mentioned: 0 Post(s)	Fuel Pump Assembly Question I recently removed my fuel pump assembly to siphon out my tank. After re-installing and filling tank back up with 10 gallons of fuel, my gauge only reads 1/2 full. Does anyone know if this has to do with how the tank transfers the fuel from one side to the other or does it have to do more with how I re-installed the assembly unit? Could there have been a possibility of the float getting moved around or something? I know I had to push down and twist the assembly a bit when I re-installed it. Anyone else run into this issue. Any help would be appreciated.

01-08-2018, 03:09 AM	#2
Mr.ac [insert cool phrase here] Join Date: Aug 2015 Drives: BRZ Premium Location: Central Coast CA Posts: 2,368 Thanks: 709 Thanked 1,559 Times in 930 Posts Mentioned: 30 Post(s)	Yep. Done screwed it. No worrries. It happens a lot when you mess with fuel pumps unknowingly. Either buy new parts or try it again. Might want to re read the repair manual again, or take it to a shop. __________________ New daily driver - Subaru BRZ Premium Weekend fun/track car - '91 MR2 Turbo Gen3 Old daily driver - '88 MR2 Supercharged

01-08-2018, 02:27 PM	#4
Sapphireho Famous Potatoes Join Date: Mar 2016 Drives: '15 ultramarine Location: Idaho Posts: 14,097 Thanks: 5,833 Thanked 19,731 Times in 9,284 Posts Mentioned: 163 Post(s)	Also note that there are many non-reusable parts when re-assembling. Attached Images

01-08-2018, 07:14 PM	#6
amanzoli Member Join Date: Apr 2016 Drives: 2015 Subaru BRZ series.blue Location: Northern California Posts: 24 Thanks: 2 Thanked 6 Times in 6 Posts Mentioned: 0 Post(s)	I did not replace anything only pulled it out to siphon. I did not repair anything, I just pulled out the assembly to place a siphon tube in the tank, so I could siphon the fuel. Perhaps the float got stuck on on something. I don't know, I may have to try to reposition it. Problem is, it's such a hassle to get the assembly in right each time.

01-08-2018, 11:03 PM	#10
Ultramaroon not playing cards Join Date: Sep 2014 Drives: a 13 e8h frs Location: vantucky, wa Posts: 32,394 Thanks: 53,054 Thanked 37,230 Times in 19,309 Posts Mentioned: 1118 Post(s)	There's something weird about how the fuel level sensing works. Many people here have had issues with the not going to full because they were in the habit of topping off instead of running below a quarter tank. I won't pretend to understand why but it's real. If you're pretty sure you got it together ok, maybe try just driving it empty and see if the system sorts itself out. __________________ service manuals

01-08-2018, 01:25 PM	#3
humfrz Senior Member Join Date: May 2013 Drives: 2013 FR-S, white, MT Location: Puyallup, WA Posts: 30,436 Thanks: 29,833 Thanked 32,866 Times in 16,849 Posts Mentioned: 717 Post(s)	I'll vote for the "take it out and try again" approach. humfrz

01-08-2018, 07:28 PM	#7
davidsn_670 Member Join Date: Oct 2015 Drives: 2015 Scion FRS Location: Tacoma, WA Posts: 44 Thanks: 23 Thanked 11 Times in 8 Posts Mentioned: 1 Post(s)	To rule out a faulty fuel level sensor, you can use a multimeter set to ohm's and check continuity while slowly sweeping the float up and down. See if there is a break in continuity. But sounds like you may have twisted it causing the terminals to not fully contact each other. Or pull the assembly out and see if the gauge reads full when you manually move the float.

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