Fuel Issues at the Track

[barbaro]

Lapping Big Willow yesterday and noticed that car was was bogging on turn 4 and I was noticing some other minor fuel interruptions in turn 2, both right hand turns. Was forced to run all day with a full or near full tank to remedy the situation. Does anybody know of a device that can combat this problem? A pressurized fuel tank would work I suppose but not feeling like driving around with a bomb strapped to my car.

I have heard of a type of floating fuel intake but have not seen one for sale.

 

[Roadracer350]

I know in the fuel cells you run baffles and foam but not sure about a stock tank.

 

[barbaro]

Well your a handy guy RR350. Make one and I will buy it! Seriously though, I can't be the only person who has noticed this. Other guys on the track were having the same problem. What would it take to fabricate a fuel tank that will keep the fuel supply steady while cornering.What kind of tanks do the 302s and 302r's run?

 

[NoTicket]

When I bought my car it had a bad secondary fuel pickup. If the gas went below a quarter of a tank the gas tank would be starved and read empty. Might be related as I'm sure the pickup would not have functioned properly on the track leaving the primary fuel pump free of gas as it all sloshed to the side.

Of course it could also be something worse... Like oil starvation.

 

[SoundGuyDave]

Intetesting... On the 5.0 cars, is the pump still on the driver's side? If so, you may not be having a starvation issue when turning right, unless the venturi pickup is having issues. Your best bet is probably to datalog fuel rail pressure and pump duty cycle and see if you can recreate the issue. Also grab oil pressure, oil temp, CHT, spark source and fuel source PIDs while you're at it. From your ddescription, it does sound like fuel sag, but whether it's mechanical in origin, or if it's PCM commanded isn't always obvious.

 

[NoTicket]

Yeah the 5.0 tank has the pump on the driver side and a pick up on the passenger side.

 

[barbaro]

Yeah the 5.0 tank has the pump on the driver side and a pick up on the passenger side.

That explains it. Turn 4 is an uphill./ downhill wide looping right turn. The centripetal force is forcing fuel on to the driver's side away from the pick-up.

I have been there four times before and this is the first I have had of this issue. It is not uncommon though. I have heard of a floating pickup that is suppose to remedy this problem but have not seen one.

 

[barbaro]

Intetesting... On the 5.0 cars, is the pump still on the driver's side? If so, you may not be having a starvation issue when turning right, unless the venturi pickup is having issues. Your best bet is probably to datalog fuel rail pressure and pump duty cycle and see if you can recreate the issue. Also grab oil pressure, oil temp, CHT, spark source and fuel source PIDs while you're at it. From your ddescription, it does sound like fuel sag, but whether it's mechanical in origin, or if it's PCM commanded isn't always obvious.

If we were in England. Pickup is on the passenger side apparently. I, unfortunately, am not capable of data logging anything. But in this case I don't think it was necessary. The car peformed great everywhere else. If it was an intermittent fuel problem, I would expect to see it somewhere else on the track rather than repeating itself on the same corner. Also, filling up cured the problem. But if it happens again I will, have my buddy come out with his lap top. It would be a bigger problem if I was supercharged, which, is why I am not supercharged. Sure would be nice if the problem could be fixed though.

 

[SoundGuyDave]

You guys DO realise that "the pickup" is at the bottom of the fuel pump, right? Yes, there is a secondary, transfer line from the passenger side, but yhat only serves to (attempt to) equalize the levels in both tank sumps, nothing more. If you wete getting starvation issues on left turns, that ttansfer tibe may have gotten disconnected, but on right turns? Something else is going on.

 

[Whiskey11]

Must be a 5.0 problem as my poor asthmatic 4.6L 3V will run without fuel starve all the way down to 5 miles till empty... I've done it a few times accidentally without any issues. I'm interested in this thread if for no other reason than general knowledge for later if it does become an issue.

 

[csamsh]

I know that Terry Fair had increasingly bad starvation problems as he added more tire and aero to his car. He needs a half a tank at least to get the car all the way around a track with no problems.

 

[jayel579]

Are you having fuel starve issues or just a low fuel warning level on the dash? I have had a number of conversations with a couple of guys here regarding the low fuel warning level on the dash.

 

[NDSP]

My 4.6 will make the low fuel light bing and the read empty in right handers if I get below half a tank. I haven't noticed fuel starvation, but definitely a bit disconcerting.

 

[NoTicket]

I haven't had any fuel starvation in my 5.0 but I am on basically stock everything so probably not pulling over a G.

 

[barbaro]

You guys DO realise that "the pickup" is at the bottom of the fuel pump, right? Yes, there is a secondary, transfer line from the passenger side, but yhat only serves to (attempt to) equalize the levels in both tank sumps, nothing more. If you wete getting starvation issues on left turns, that ttansfer tibe may have gotten disconnected, but on right turns? Something else is going on.

Well that complicates things. I don't have real good explanation then. I was bogging in the same right turn with 2/3 of a tank. Fill her up and it runs like a charm. Have not noticed this issue anywhere else but turn 4 and to a lesser extent turn 2 which is a long sweeping right hander. Turn 8, which is a long sweeping right hander, no problems. It may be the elevation and road camber change on 3-4 gets the gas unsettled causing air pockets in the fuel line. how exactly that is happening is a mystery .

 

[SoundGuyDave]

Well that complicates things. I don't have real good explanation then. I was bogging in the same right turn with 2/3 of a tank. Fill her up and it runs like a charm. Have not noticed this issue anywhere else but turn 4 and to a lesser extent turn 2 which is a long sweeping right hander. Turn 8, which is a long sweeping right hander, no problems. It may be the elevation and road camber change on 3-4 gets the gas unsettled causing air pockets in the fuel line. how exactly that is happening is a mystery .

That's why I'm thinking it may be something else masquerading as fuel sag. Datalogging may be your best bet to resolve it. FWIW, actual sag will show as a pressure drop at the rail with simultaneous increase in pump duty cycle, probably hitting 100%. There is a LOT that goes on in the PCM, though, hence my suggestions to log the spark and fuel source values. If for some reason the PCM is commanding a drop in fuel or a throttle cut, the source value will at least point you towards the "offending" module. I'm pretty sure the Mustang doesn't, but the C6Z06 and current BMW M3 both pull throttle as part of the DSC strategy. Just something to think about.

 

[barbaro]

That's why I'm thinking it may be something else masquerading as fuel sag. Datalogging may be your best bet to resolve it. FWIW, actual sag will show as a pressure drop at the rail with simultaneous increase in pump duty cycle, probably hitting 100%. There is a LOT that goes on in the PCM, though, hence my suggestions to log the spark and fuel source values. If for some reason the PCM is commanding a drop in fuel or a throttle cut, the source value will at least point you towards the "offending" module. I'm pretty sure the Mustang doesn't, but the C6Z06 and current BMW M3 both pull throttle as part of the DSC strategy. Just something to think about.

Sounds plausible. I will try to recreate the condition and datalog accordingly.

 

[SD_Stang]

When I bought my car it had a bad secondary fuel pickup. If the gas went below a quarter of a tank the gas tank would be starved and read empty. Might be related as I'm sure the pickup would not have functioned properly on the track leaving the primary fuel pump free of gas as it all sloshed to the side.

Of course it could also be something worse... Like oil starvation.

The 2011's had this issue and there was a TSB for it. My 2011 if I did any hard braking my gas gauge would go from full to empty the car would still run but iwould have to turn it off to reset and sometimes even that wouldn't fix it right away.

Dealer replaced it under warranty. Not sure of the TSB number but if you never had it done it maybe worth a look.

 

[NoTicket]

The 2011's had this issue and there was a TSB for it. My 2011 if I did any hard braking my gas gauge would go from full to empty the car would still run but iwould have to turn it off to reset and sometimes even that wouldn't fix it right away.

Dealer replaced it under warranty. Not sure of the TSB number but if you never had it done it maybe worth a look.

I brought it in and they replaced it under the same TSB.

 

[Roadracer350]

Well your a handy guy RR350. Make one and I will buy it! Seriously though, I can't be the only person who has noticed this. Other guys on the track were having the same problem. What would it take to fabricate a fuel tank that will keep the fuel supply steady while cornering.What kind of tanks do the 302s and 302r's run?

It would be cheaper for you to source one from a place like Jaz.