Fuel Starvation Fix

[LucyFord]

Guys,

I was recently at the track and found that my 91 legacy has fuel starvation issues when there is less the 1/2 a tank. I searched NASIOC after not finding anything here and found this treasure http://www.ludicrous-speed.com/wiki/ind ... _slosh_mod

Is our fuel pump similar enough to the 2.5RS's that this fix might work? I would like to order parts as soon as possible.


Thanks!

[Legacy777]

Yes, our fuel pump setup is identical.

That fix is a pretty clever idea and a lot cheaper than adding a swirl pot down stream of the fuel pump.

[LucyFord]

Yeah, swirl pot down stream was not a option for me so this will have to do. I will post up my results and findings. Thanks Josh for confirming that those fuel pumps are the same.

[AWD_addict]

Resourceful and cheap, that tank is a $5 part.

[kimokalihi]

Cool idea.

[LucyFord]

So far so good. I bought my tank from here

http://www3.towerhobbies.com/cgi-bin/wt ... XD724&P=ML

I installed it the other night. It was a snug fit but i got it in there.

[Legacy777]

Good deal!

[LucyFord]

Still wasn't happy with this slosh tank. I think i might have drilled to many holes but i don't have the track time to find out. So i am going to add a cross tank pump that sits on the drivers side of the tank and feeds fuel into the slosh tank on the pass side. Build the mount out of some scrap aluminum and a magnet i found at harbor freight. Had a old 2.5RS fuel pump laying around. I believe I am going to piggy back the wiring off the stock pump. Not sure yet because that is scary.

[Legacy777]

I honestly don't think that's going to really help. There is already a jet pump on the driver's side to move fuel back to the passenger side. Without a sump or some sort of baffling on the driver's side the additional pump will likely not be too effective.

To really fix the issue, you'll need some sort of surge tank downstream of the main fuel pump, and possibly an additional fuel pump.

[LucyFord]

I honestly don't think that's going to really help. There is already a jet pump on the driver's side to move fuel back to the passenger side. Without a sump or some sort of baffling on the driver's side the additional pump will likely not be too effective.

To really fix the issue, you'll need some sort of surge tank downstream of the main fuel pump, and possibly an additional fuel pump.

I don't completely agree. But i do think adding baffling around the cross pump is a good idea. I will do this (i have another RC tank).

Honestly not a huge fan of the return jets location. If anything it will create aeration when suffering from fuel surge.

I will tell you how it goes after the track day. Thanks for the idea about the baffling i was hoping you would post about this.

[Legacy777]

Ok, yeah let us know if the baffling helps.

[LucyFord]

Here it is with the baffling. So the cross hose dumps into a hole i drilled on the baffling i added to the stock pump.

Installed it in the car last night. everything seems to run good for now.

[LucyFord]

Ran a test last night. I drained the fuel until the low fuel light turned on and took her to a freeway on ramp (one of the cloverleaf ones) at took it at full speed. No fuel slosh, I even added a low fuel pressure light and that didnt go off ethier.

When draining the fuel I did notice out fuel was a little discolored from the unneeded eletrical tape used.

[Legacy777]

Well that's good to hear that the baffles helped!

[LucyFord]

Update: took car to a track and it ran without a trace of fuel slosh until well after the low fuel light turned on. I believe there was only 1.8ish gallons of fuel left when we started to notice it

[Legacy777]

Well that's pretty good results I would say!

[LucyFord]

Well that's pretty good results I would say!

Yeah I was super happy with it. Thanks for the baffle idea.

[LucyFord]

Just realized that there is are two inspection covers on the tank (drivers and pass side). There is another pick up on the drives side and fuel level sensor (so there are two) but i believe the pick up runs on vacuum (not sure). I will look into it some more.

But this allowed me to better place my secondary mag mounted pump. Before I just kinda threw it in there because i couldn't reach over to the drivers side from the pass side inspection cover

[Legacy777]

Yeah, the driver's side utilizes a "jet pump" The return fuel stream going back to the tank is used to create a venturi effect and draws fuel from the driver's side to the passenger side. I don't think you'd see a huge benefit in putting an additional box/sump around the jet pump

[biggreen96]

Awesome idea! I was having this issue with the old rally car on hairpins, the next one will have this mod.

[CFK]

Anybody else do this mod ?

Installed the slosh box last night using a 32oz Sulivan RC tank. Very very tight fit, both in the top hole and bottom little pan, I had to force it right down into it and could barely get the nuts on.

Also the filter bag sat on the base of the RC tank. Not sure if my holes were to big or located in the wrong place or what ?

Pretty disappointed , might try again with a 26oz tank or find the STI slosh box. Really don't wanna have to install a second pump on the drivers side.

Or I join NASCAR, not to sure yet ?

Hard to explain, pics to follow

[James614]

I've been thinking about this mod, I used to hit fuel cut ALL THE TIME during autoX. After reading about this I'm wondering if it was really fuel cut. Meh, gotta get my swap running past 2500rpm first...