Fuel gets low and develops an issue at WOT?

Right chaps need to pick your brains! My car drives and boosts perfect until it gets to between a quarter of a tank of fuel and the light coming on. Could it be that once the fuel gets low in the tank and at WOT pushes the fuel to the back of the tank! Could the pump be having problems lifting the fuel when it's low if there is a pump issue?? Only does it when the fuel gets low it's bloody weird. As far as i know it's a Wallbero pump. Yes i know the easy fix is to keep the fuel higher than a quarter tank Just wondering what the root problem could be.

Thanks.

Could it be the fuel getting hot and with only a small amount of fuel in there, it's all getting warmer quicker and then affecting your AFR's?

Or is your needle accurate and the pump is actually sucking on empty lol

Could it be the fuel getting hot and with only a small amount of fuel in there, it's all getting warmer quicker and then affecting your AFR's?

Or is your needle accurate and the pump is actually sucking on empty lol

I'm really not sure at all. Needle is accurate enough theres never been a problem with that. It's certainly strange one I will keep it topped up above the quarter for now but could do with identifying whats up.

Even when my tank is empty it still pulls as hard as ever (except that time it hit 1.5bar for half a second lol)

Yeah Josh even if its low it should still pull and drive just the same.

Mine does the same mate

No idea why just guessed that the fuel goes back to tank and sucks empty so make sure I always got decent amount in

Mine does it too. Even more so when it has rubbish fuel in it (only in emergencies!)

My next step (as I changed the plugs, coil packs, and clips) is to change the fuel filter. The theory being, as the fuel gets low, more gunk from the bottom of the tank gets sucked up, and clogs the filter. I may be wrong, but hey, it will be another thing ruled out.

Mine does the same mate

No idea why just guessed that the fuel goes back to tank and sucks empty so make sure I always got decent amount in

Bugger I bought new plugs, fuel filter, coil packs and clips even got the bloody vac lines changed trying to solve it. Oh well better keep plenty fuel in from now on. I never noticed it doing it before.

The theory being, as the fuel gets low, more gunk from the bottom of the tank gets sucked up, and clogs the filter. I may be wrong, but hey, it will be another thing ruled out.

Think you'll find there's no "gunk" at the bottom of the tank, certainly not in this day and age. Even what are now 20 year old fuel pump filters come out clean if a little stained.

Tony have you taken the fuel pump out and checked it's definitely an uprated pump?

Would be worth doing just for peace of mind and to check the connections and soldering.

Also it's worth noting that for some reason the Walbro fuel pump comes with a smaller filter bag which means it is probably more susceptible to the fuel moving about, as the pick up area once they fuel is low will be smaller. I've always reused the OEM filter with the 4 or 5 that I've fitted.

Think you'll find there's no "gunk" at the bottom of the tank, certainly not in this day and age. Even what are now 20 year old fuel pump filters come out clean if a little stained.

 

Tony have you taken the fuel pump out and checked it's definitely an uprated pump?

Would be worth doing just for peace of mind and to check the connections and soldering.

Also it's worth noting that for some reason the Walbro fuel pump comes with a smaller filter bag which means it is probably more susceptible to the fuel moving about, as the pick up area once they fuel is low will be smaller. I've always reused the OEM filter with the 4 or 5 that I've fitted.

It's defo a walbero mate its working fine at bpu with no issues till the level gets low. I may opt for a Bosch now though.

I was using a U.K. pump and hanger in a J spec tank and had the same issue, now running the U.K. pump and hanger in a U.K. tank and the problem has gone.

U.K. tanks have extra plumbing in the centre baffle that directs returned fuel to the the centre of the baffle, J spec just blasts the returned fuel in the general direction.

When fuel is below the baffle top, I think it could be pumped out quicker than it can get in.

Try Fitting a short hose to the return pipe to feed the fuel into the centre.

J spec

U.K. spec

I was using a U.K. pump and hanger in a J spec tank and had the same issue, now running the U.K. pump and hanger in a U.K. tank and the problem has gone.

 

U.K. tanks have extra plumbing in the centre baffle that directs returned fuel to the the centre of the baffle, J spec just blasts the returned fuel in the general direction.

 

When fuel is below the baffle top, I think it could be pumped out quicker than it can get in.

 

Try Fitting a short hose to the return pipe to feed the fuel into the centre.

 

 

J spec

 

http://www.mkivsupra.net/vbb/attachment.php?attachmentid=174107&d=1377390970

 

U.K. spec

 

http://www.mkivsupra.net/vbb/attachment.php?attachmentid=174108&d=1377390970

Interesting. It didn't do it before though which is making me wonder what's changed. The last supra I had was also a j-spec and that didn't do it.

Mine surposily has an updated pump

I also changed the fuel filter Whitchurch did nothing to help also

Thanks for that David might be worth a try