Ian's 99 build thread
#841
SADFab Destructive Testing Engineer
![](/mt2011/images_td/ranks/supporter1.gif)
![](/mt2011/images_td/ranks/moderator.png)
iTrader: (5)
Join Date: Apr 2014
Location: Beaverton, USA
Posts: 18,642
Total Cats: 1,866
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
I think you should mount a go pro in the tank and see what it looks like at low fuel level.
Is it the stock hangar? I know there are some differences in hangars between the years.
Is it the stock hangar? I know there are some differences in hangars between the years.
#844
Elite Member
![](/mt2011/images_td/ranks/supporter1.gif)
Thread Starter
Join Date: Mar 2007
Location: Santa Clara, CA
Posts: 5,178
Total Cats: 858
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
I know I posted this video on mt.net, but can't find it in my build thread. Maybe it was another thread. This is what a fuel pump prime looks like inside the tank.
--Ian
#847
Elite Member
iTrader: (37)
Join Date: Apr 2010
Location: Very NorCal
Posts: 10,448
Total Cats: 1,900
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
I was running this exact same in-tank configuration when I had the return setup, and I had no issues.
DW200 on OEM hangar, DW provided filter sock FWIW.
I could see this creating aeration in the fuel causing the pump to suck up some air? But beyond that you got me. Maybe order one of those fuel rail regulator adapters with the male AN fitting on it (because IIRC its the same bolt pattern) and throw an 90° fitting on it and shoot the return fuel off to the side somewhere. It may not accomplish anything, but for <$20 worth of parts it might be fun to test.
Of course, if this was the real issue, I feel like we would be seeing it more frequently.
Just a thought.
DW200 on OEM hangar, DW provided filter sock FWIW.
Of course, if this was the real issue, I feel like we would be seeing it more frequently.
Just a thought.
![Dunno](https://www.miataturbo.net/images/smilies/dunno.gif)
#848
SADFab Destructive Testing Engineer
![](/mt2011/images_td/ranks/supporter1.gif)
![](/mt2011/images_td/ranks/moderator.png)
iTrader: (5)
Join Date: Apr 2014
Location: Beaverton, USA
Posts: 18,642
Total Cats: 1,866
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
I'm more curious to see if the sock sees air when in turns. Then you could compare it to a car that doesnt see fuel starvation, and see if the sock is seeing air then.
#849
Supporting Vendor
![](/mt2011/images_td/ranks/vendor.png)
![](/mt2011/images_td/ranks/supporter1.gif)
iTrader: (1)
Join Date: Sep 2010
Location: Lake Forest, CA
Posts: 7,976
Total Cats: 1,019
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
Indeed I have a return system, and indeed I have the same problem. 1/4 tank and below and I'm hosed. I can run it down below a half tank though, so it does sound like my fuel starvation issue is not as extreme as yours.
#854
Retired Mech Design Engr
![](/mt2011/images_td/ranks/supporter1.gif)
iTrader: (3)
Join Date: Jan 2013
Location: Seneca, SC
Posts: 5,011
Total Cats: 859
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
I, too, wondered about return turbulence. I suppose we could weld up a flange and tube. However, this video, and other evidence is that bubbling is not the cause.
Another thing I noticed. When I pulled the original pump, it took about 5 seconds for the fuel to all run out of the expanded sock.
However, the old, stock sock was so loose on the new DW pump, that I used the one from DW, instead of re-using the stock one. Later, I pulled this assembly and the fuel ran out of the DW sock in about half a second.
Miata does not sell the OEM sock as a separate item.
Another thing I noticed. When I pulled the original pump, it took about 5 seconds for the fuel to all run out of the expanded sock.
However, the old, stock sock was so loose on the new DW pump, that I used the one from DW, instead of re-using the stock one. Later, I pulled this assembly and the fuel ran out of the DW sock in about half a second.
Miata does not sell the OEM sock as a separate item.
#856
Retired Mech Design Engr
![](/mt2011/images_td/ranks/supporter1.gif)
iTrader: (3)
Join Date: Jan 2013
Location: Seneca, SC
Posts: 5,011
Total Cats: 859
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
Also, looks like when under high power, you are returning very little fuel to the tank. Is it possible you are running out of pump? 'Course that should change conditions much between full and empty tank.
EDIT: NVM. This is cycling pump. Duh… reading fail.
EDIT: NVM. This is cycling pump. Duh… reading fail.
Last edited by DNMakinson; 04-14-2017 at 06:20 PM. Reason: Brain Fart
#858
Elite Member
![](/mt2011/images_td/ranks/supporter1.gif)
Thread Starter
Join Date: Mar 2007
Location: Santa Clara, CA
Posts: 5,178
Total Cats: 858
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
Assuming you mean "Mazda", sure they do, I bought one. Looks like it's part # BP4W-13-ZE1 (at least, for an NB1, didn't check other years). "Filter, fuel pump."
I swapped out the one that had come with my Walbro for a new OEM one back when I was first investigating this problem last summer (a few pages back on the build thread). The OEM sock is held open with a spring, the Walbro one is not. The OEM sock went onto the Walbro input just fine, no rattling. Haven't tried a DW pump.
It didn't make any difference in the fuel starvation, though.
--Ian
I swapped out the one that had come with my Walbro for a new OEM one back when I was first investigating this problem last summer (a few pages back on the build thread). The OEM sock is held open with a spring, the Walbro one is not. The OEM sock went onto the Walbro input just fine, no rattling. Haven't tried a DW pump.
It didn't make any difference in the fuel starvation, though.
--Ian
#859
Retired Mech Design Engr
![](/mt2011/images_td/ranks/supporter1.gif)
iTrader: (3)
Join Date: Jan 2013
Location: Seneca, SC
Posts: 5,011
Total Cats: 859
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
@turbofan how did you get just a new OEM sock? https://www.miataturbo.net/race-prep...handers-89826/
Also, in above thread, Ian says he has an OEM sock, but pic on post 6 is not an OEM sock.
Also, in above thread, Ian says he has an OEM sock, but pic on post 6 is not an OEM sock.