Anyone find a fix for fuel sloshing and starvation?

[blacksheep-1]

To add some verbiage to this, we just ( thank God, finally) solved an S197 fuel starvation issue with one of the cars. They had been fighting it for over a year. The car would actually run for hours, through a couple of pit stops, then with a full fuel cell, would run out of fuel. Swapped cells/ pumps/ plumbing/ divorced pumps/ regulators/ vents and even harnesses. Finally ( another) in tank pump fixed it.. at least it ran for about 6 hours without issue.
On superbeater, it took at least half a tank to overcome a low fuel alert with the stock tanks.
Pretty much over fuel issues..

 

[TennTex]

To add some verbiage to this, we just ( thank God, finally) solved an S197 fuel starvation issue with one of the cars. They had been fighting it for over a year. The car would actually run for hours, through a couple of pit stops, then with a full fuel cell, would run out of fuel. Swapped cells/ pumps/ plumbing/ divorced pumps/ regulators/ vents and even harnesses. Finally ( another) in tank pump fixed it.. at least it ran for about 6 hours without issue.
On superbeater, it took at least half a tank to overcome a low fuel alert with the stock tanks.
Pretty much over fuel issues..

Wow, that's odd, glad y'all found a fix!
Reminds me of the basics I learned from my Dad while riding dirt bikes as a kid - you gotta have air + fuel + spark if you want the engine to run!

 

[stevbd]

So in chasing a random misfire and 0300 codes that I've been getting on track but not on the street, I read this entire thread, tore apart my fuel pump system, and learned a few things that others might find helpful.

TLDR - you need to replace your fuel pump in order to replace your fuel filter if you've got a 2011-2014 S197, and the internal fuel filter is not "lifetime." And the way the fuel pump system is designed, I can't see any advantage to running with a full tank of gas on track to avoid fuel starvation in corners.

As background I've got a 2011 GT with 165,000 miles, street/track, original and stock drivetrain but coilovers and 305 tires for track. So it makes decent lateral g's. But my thoughts are limited to this kind of a 'tweener car and things likely will be different with a real race car.

1. The 2005-2010 S197 has an external fuel filter. On 2011-2014 the filter is internal to the fuel pump and Ford calls it a "lifetime" filter. That is a lie. Because I'm not much of a mechanic and I have so many miles on my car, I started just throwing parts at my problem including a new stock fuel pump. I took apart the old one in the name of science and when I got to the "lifetime" filter and its chamber, an absolute ton of completely black fuel poured out. I removed and cut apart the filter and it was totally filled with dirt and grime, very dark gray color on the outside, super dirty, everything you would expect from a 165,000 mile fuel filter.

2. In a GT, there is only one fuel pump on the driver side of the saddle tank. It sits in a plastic basket that is full of fuel and open at the top. In the pressure side line from the pump to the engine, there is a vortex-style siphon valve (aka "jet pump") that is hooked up to a low pressure hose that runs from the passenger side of the saddle tank over to the fuel pump basket. That low pressure hose pulls fuel from the right side of the tank to the left side by way of the fuel pump basket but in no way does it supply fuel directly to the engine. The fuel pump only pulls fuel for the engine from the fuel pump basket. The fuel pump basket can be filled by fuel from both the left and right side of the tank if the right side is full, or from the left side alone if the right side tank is empty.

3. On the right side of the tank, on the other end of that low pressure hose, there is a sender valve and a separate float so the fuel gauge can correctly report fuel level. But there is no pump of any sort.

4. Because the siphon or "jet pump" is always operating whenever the fuel pump is running, the right side of the tank gets drained before the left side. I don't know exactly how fast each side drains but they don't go down equally. I can report that with about 3 gallons of fuel still in the driver side of my gas tank, the passenger side was totally dry. I have seen reports that the passenger side float measures from full to 1/2 tank on your gauge and the driver side float measures from 1/2 to E.

5. The effect of all this is that the fuel pump doesn't know the difference between a full tank of gas and a half tank. Once you get down below half a tank, maybe towards 1/4 tank, then yes, at that point the fuel pump is getting more exposed to air and you might start to see some fuel starvation issues. But even then, the pickup on the pump sits inside a separate plastic "basket" which further helps prevent sloshing and fuel starvation.

6. I think the dual fuel pumps on the GT500 and the like are designed to provide the needed extra fuel for those big motors. But based on the design I was looking at in my car, I don't see how dual pumps would help prevent fuel starvation due to lat g's.

Just my observations, sorry for the long post and I hope this might be helpful to someone else battling similar problems. If you've got an old 2011-2014, replace the fuel pump so you can get a clean filter.

 

[TennTex]

4. Because the siphon or "jet pump" is always operating whenever the fuel pump is running, the right side of the tank gets drained before the left side. I don't know exactly how fast each side drains but they don't go down equally. I can report that with about 3 gallons of fuel still in the driver side of my gas tank, the passenger side was totally dry. I have seen reports that the passenger side float measures from full to 1/2 tank on your gauge and the driver side float measures from 1/2 to E.

5. The effect of all this is that the fuel pump doesn't know the difference between a full tank of gas and a half tank. Once you get down below half a tank, maybe towards 1/4 tank, then yes, at that point the fuel pump is getting more exposed to air and you might start to see some fuel starvation issues. But even then, the pickup on the pump sits inside a separate plastic "basket" which further helps prevent sloshing and fuel starvation.

Great info in your post, especially the point about the fuel filter - sorry mine is an S550, but found this post helpful on "this side of the fence". I always read both, as there are so many similarities between S197's and S550's.

Everything you said about the siphon/jet pump is correct. The only problem is that the flow rate is much lower than what is needed to keep the main fuel pump basket full of fuel - in my case specifically at one set of turns at one track, where you rotate the car about 270 deg through a triple apex turn at 1.3+ G's over 12 seconds. Never really had a problem anywhere else.

 

[xr7]

Just my observations, sorry for the long post and I hope this might be helpful to someone else battling similar problems. If you've got an old 2011-2014, replace the fuel pump so you can get a clean filter.

Any chance you could post some photos of the fuel pump you opened up?

​

 

[stevbd]

The only problem is that the flow rate is much lower than what is needed to keep the main fuel pump basket full of fuel - in my case specifically at one set of turns at one track, where you rotate the car about 270 deg through a triple apex turn at 1.3+ G's over 12 seconds.

I don't doubt your experience but I must be missing something. I don't see how the system depends on the siphon/jet pump hose to keep the fuel pump basket full. My understanding is that below about 1/2 on the gauge the passenger side tank chamber is likely dry so the flow rate through the siphon hose is essentially zero but the fuel basket is still full and the car runs fine. Again, when I pulled my fuel pump I removed about 3 gallons of fuel from the driver side of the saddle tank but the passenger side was totally dry. What does your fuel gauge read when you have this problem in the 270 degree corner? Other than your mod to the siphon hose, do you have the stock fuel pump setup?

EDIT: The only thing I can think of is that perhaps the fuel pump somehow under extended high load conditions can drain the fuel pump basket faster than it can be refilled, especially if the right side tank is empty? I'm just guessing here. But your experience caused me to realize I mis-spoke a bit in my No. 2 above, which I went back and corrected. More accurately, the siphon hose from the right side chamber drains into the fuel pump basket, which can overflow into the left side tank chamber.

Any chance you could post some photos of the fuel pump you opened up?

​

I'm sorry, I stupidly didn't take pictures and threw out the pieces of my old pump. It was surprisingly difficult to tear apart!

 

[67GTA]

And the way the fuel pump system is designed, I can't see any advantage to running with a full tank of gas on track to avoid fuel starvation in corners.

The starvation is definitely caused/amplified by high g-loads in left hand turns. When I was running 200tw tires and a softer coilover setup, I could easily run under 1/2 tank without fuel cut. With r-compound tires and Cortex coilover setup, I’ll get fuel starve on certain LH turns at 3/4’s of a tank. Seems to be more prevalent with e85 as well, which could be related to higher consumption rate vs gas.

 

[stevbd]

@TennTex @67GTA I am seeing the light.... 1.3 g's, R-comp tires, I guess I'm just not going fast enough lol. You guys must be moving pretty much all the fuel from the driver side chamber over to the passenger side, which is impressive.

 

[67GTA]

@TennTex @67GTA I am seeing the light.... 1.3 g's, R-comp tires, I guess I'm just not going fast enough lol. You guys must be moving pretty much all the fuel from the driver side chamber over to the passenger side, which is impressive.

Lol, yeah, it took a few years and some key mods for this issue to come to light. I need the extra fuel load for ballast to stay in class so I haven’t addressed it yet - just go out full to the top each session.

 

[blacksheep-1]

Lol, yeah, it took a few years and some key mods for this issue to come to light. I need the extra fuel load for ballast to stay in class so I haven’t addressed it yet - just go out full to the top each session.

I just ran into this myself at the autocross on the race track at the FIRM. I threw in another 5 gallons and it seemed to go away, I don't think I ever actually got starvation, but the dash kept saying I was only 25 miles to empty in the corners.

 

[stevbd]

I just ran into this myself at the autocross on the race track at the FIRM. I threw in another 5 gallons and it seemed to go away, I don't think I ever actually got starvation, but the dash kept saying I was only 25 miles to empty in the corners.

@blacksheep-1 that's a great point, are others getting the 50 or 25 miles to E alert when you get these fuel starvation issues? That obviously would seem to be a great clue it's the fuel sloshing over to the right side chamber as opposed to some other problem.

 

[TennTex]

@stevbd
Yeah, it is G's and track dependent. I'm referring to Motorsport Ranch Cresson turns Horseshoe-Boot Hill - Tombstone. I started at this track years ago and never had a problem, but have really been trying to push to improve lap times. In fact, when I first had it happen at track-out, I thought I was hitting the rev limiter - it was very subtle.

A year or two ago I figured out it was fuel starvation and I was good as long as I kept over 1/2 tank (indicated), then in the last year or so it has become 3/4 tank. I can just about survive the first 20~25 min session with a full tank of gas, and I burn ~5 gallons, so while that indicates roughly 3/4 tank, the actual capacity remaining is probably closer to 2/3 tank - IIRC our tanks are ~16 gallons.

To answer your other question, yes fully stock fuel setup, I was looking for a low-buck way to solve this problem, and so far so good with this mod - I've purposely run down to 1/8 tank on track with no starvation.

 

[Dave_W]

Since the issue seems to be fuel slosh under high g-forces from the driver's "saddle bag" to the passenger's "saddle bag" has anyone looked at ways to prevent the fuel slosh in the first place?


Can fuel cell foam be jammed into the "throat" between the saddle tanks? Of course, that might hamper filling both tanks evenly at the pump, but if a large pipe was used to connect the two sides without the pipe openings being at the edge of each saddle tank, that could help. How permeable is fuel cell foam? Artist's rendering by a person with no artistic talent.

You'd still use the siphon hose to pull fuel from the passenger side to the driver side.

 

[stevbd]

@Dave_W that is an ingeniously simple looking solution especially your idea about the pipe.

 

[xr7]

Since the issue seems to be fuel slosh under high g-forces from the driver's "saddle bag" to the passenger's "saddle bag" has anyone looked at ways to prevent the fuel slosh in the first place?

View attachment 87267
Can fuel cell foam be jammed into the "throat" between the saddle tanks? Of course, that might hamper filling both tanks evenly at the pump, but if a large pipe was used to connect the two sides without the pipe openings being at the edge of each saddle tank, that could help. How permeable is fuel cell foam? Artist's rendering by a person with no artistic talent.
View attachment 87268
You'd still use the siphon hose to pull fuel from the passenger side to the driver side.

I was thinking something like baffles, I like your idea

 

[twistedneck]

So in chasing a random misfire and 0300 codes that I've been getting on track but not on the street, I read this entire thread, tore apart my fuel pump system, and learned a few things that others might find helpful.

TLDR - you need to replace your fuel pump in order to replace your fuel filter if you've got a 2011-2014 S197, and the internal fuel filter is not "lifetime." And the way the fuel pump system is designed, I can't see any advantage to running with a full tank of gas on track to avoid fuel starvation in corners.

As background I've got a 2011 GT with 165,000 miles, street/track, original and stock drivetrain but coilovers and 305 tires for track. So it makes decent lateral g's. But my thoughts are limited to this kind of a 'tweener car and things likely will be different with a real race car.

1. The 2005-2010 S197 has an external fuel filter. On 2011-2014 the filter is internal to the fuel pump and Ford calls it a "lifetime" filter. That is a lie. Because I'm not much of a mechanic and I have so many miles on my car, I started just throwing parts at my problem including a new stock fuel pump. I took apart the old one in the name of science and when I got to the "lifetime" filter and its chamber, an absolute ton of completely black fuel poured out. I removed and cut apart the filter and it was totally filled with dirt and grime, very dark gray color on the outside, super dirty, everything you would expect from a 165,000 mile fuel filter.

2. In a GT, there is only one fuel pump on the driver side of the saddle tank. It sits in a plastic basket that is full of fuel and open at the top. In the pressure side line from the pump to the engine, there is a vortex-style siphon valve (aka "jet pump") that is hooked up to a low pressure hose that runs from the passenger side of the saddle tank over to the fuel pump basket. That low pressure hose pulls fuel from the right side of the tank to the left side by way of the fuel pump basket but in no way does it supply fuel directly to the engine. The fuel pump only pulls fuel for the engine from the fuel pump basket. The fuel pump basket can be filled by fuel from both the left and right side of the tank if the right side is full, or from the left side alone if the right side tank is empty.

3. On the right side of the tank, on the other end of that low pressure hose, there is a sender valve and a separate float so the fuel gauge can correctly report fuel level. But there is no pump of any sort.

4. Because the siphon or "jet pump" is always operating whenever the fuel pump is running, the right side of the tank gets drained before the left side. I don't know exactly how fast each side drains but they don't go down equally. I can report that with about 3 gallons of fuel still in the driver side of my gas tank, the passenger side was totally dry. I have seen reports that the passenger side float measures from full to 1/2 tank on your gauge and the driver side float measures from 1/2 to E.

5. The effect of all this is that the fuel pump doesn't know the difference between a full tank of gas and a half tank. Once you get down below half a tank, maybe towards 1/4 tank, then yes, at that point the fuel pump is getting more exposed to air and you might start to see some fuel starvation issues. But even then, the pickup on the pump sits inside a separate plastic "basket" which further helps prevent sloshing and fuel starvation.

6. I think the dual fuel pumps on the GT500 and the like are designed to provide the needed extra fuel for those big motors. But based on the design I was looking at in my car, I don't see how dual pumps would help prevent fuel starvation due to lat g's.

Just my observations, sorry for the long post and I hope this might be helpful to someone else battling similar problems. If you've got an old 2011-2014, replace the fuel pump so you can get a clean filter.

spectacular post stevbd

 

[twistedneck]

The starvation is definitely caused/amplified by high g-loads in left hand turns. When I was running 200tw tires and a softer coilover setup, I could easily run under 1/2 tank without fuel cut. With r-compound tires and Cortex coilover setup, I’ll get fuel starve on certain LH turns at 3/4’s of a tank. Seems to be more prevalent with e85 as well, which could be related to higher consumption rate vs gas.

I finally said hell with it and bout the S197 pump hanger from Radium with their built in surge basket setup (something about 3 ways it gets filled) and i got the walbro 278 pump since i make 550 engine HP on E85, that pump is good to 600HP on E85. will let you guys know if it works.
Question, what is the standard fuel pressure at idle? i'll need to match the new pump / regulator to my stock setup so i don't screw up my tune!

 

[67GTA]

I finally said hell with it and bout the S197 pump hanger from Radium with their built in surge basket setup (something about 3 ways it gets filled) and i got the walbro 278 pump since i make 550 engine HP on E85, that pump is good to 600HP on E85. will let you guys know if it works.
Question, what is the standard fuel pressure at idle? i'll need to match the new pump / regulator to my stock setup so i don't screw up my tune!

13.5 volts and 55 psi nominal. This article references a pressure relief valve in the tank that dumps at 58 psi. I’m assuming that’s part of the OE basket that’s replaced with the Radium setup? I would say the Radium pressure regulator would be set to the same 58 psi?

https://www.motortrend.com/how-to/m5lp-1304-fuel-pump-flow-test/

 

[twistedneck]

13.5 volts and 55 psi nominal. This article references a pressure relief valve in the tank that dumps at 58 psi. I’m assuming that’s part of the OE basket that’s replaced with the Radium setup? I would say the Radium pressure regulator would be set to the same 58 psi?

https://www.motortrend.com/how-to/m5lp-1304-fuel-pump-flow-test/

Hey thanks 67 GTA.. i went whole hog and got the Radium fuel rails and their sweet lookin pressure gauge so i'm also going to get a pal to read the pressure at idle before i swap everything over. I'll post back here w the result.

 

[blacksheep-1]

I'm about to do a bit of a deep dive into this myself with my 2006