Fuel Surge or Fuel Return Problem?

[Jk_zeder]

Hey guys,

 

On the weekend at Lakeside we ran into a program leaving one of the corners (hungry) that if we didn't have an absolute full tank of fuel the car would just lose all power.

 

You can see in the video

if you skip right to the end when I go to go up the inside of the porker.

 

Now I automatically thought to myself 'fuel surge, time to buy a surge tank' but remember that the tank we have has a custom baffle at the back that essentially works so the fuel is always at the outlet.

 

The guys who had the tank previously, never had any problems but were also running carbs and not EFI.

 

Another thought that was given to us was that we currently have our return line running to the back of the baffle about 6 inches to the right of the pick up (back of the tank) and that if we move the return to the top of the tank it will eliminate the problem.

 

I'd like some thoughts if you have any as I'd rather not go and set up a surge tank system if all I needed to do was drop the tank out and put a return into the top of the tank.

 

Thanks gents.

[pauly_adams]

it could be even more simple than that i would first check the wiring to your fuel pump, my 280zx use to cut out sometime on tight corners, i thought it must be due to no baffles in the tank but when i looked under there my wiring was loose, i put a new plug on my wiring to the fuel pump then had no issues.

[Zedman240®]

I'm suffering something very similar to that as well... engine cuts out during hard cornering and it has never done it before.. and I have a surge tank fitted. Thinking the lift pump can't supply enough after a long straight? I'm hoping its as simple as wiring.

[RB30X]

I'd be interested to see how your exhaust looked during the power loss. Like if it was dumping fuel or not.

Did you say you had carbs or the previous owner had carbs?

[Jk_zeder]

Previous owner had carbs. Nothing was mentioned about fuel dump etc but when Dan was driving I noticed quite a bit of black smoke leaving the corner. Gave me the impression it was fueling up to heavily? I may be wrong.

[RB30X]

Maybe there's some extra fuel going in during decceleration and its fouling the plugs for when you take off again. Sticky injector or something.

[Jk_zeder]

hmm, that's an idea. Might pull the plugs out tonight and see how they look.

[dat2kman]

Hungry corner, a left hander, tripple carbs, Webets/Dellortos,

Coming into it you are hard on gas, hit brakes while aiming for the little metal grate on rh track edge, hook left into it.

Carb float bowls have had fuel sucked out, jet pick ups uncovered, then sloshed, then covered, main circuit has had a bit too much air sucked in, hence the cough, jerk splutter, then black smoke as it has gotten a gutfull finally ( talking approx 1 to 2 seconds)

 

Looking at plugs and exhaust is a waste of time, will show zip, as by time you come into pits, engine has been running at noise for X no more minutes.

 

Try slightly increasing the float bowl levels, and make sure all are same, and ensure EACH carb is getting same volume fuel flow and pressure all same.

Look at the fuel lines going in, will one carb get less? It will if it is on end of the line.

Increase press reg by 1/2 psi only.

Only do one thing at a time, and test each time.

 

Fuel tank issue in a Z is worst at Turn 1 and Turn 2, Qld raceway,( used to be a problem at Amaroo park too),  thats when you need lift pump into surge, and push pump into carbs. Your current tank set up is fine.

[RB30X]

My bad, I thought he said it was efi.

[Jk_zeder]

My bad, I thought he said it was efi.

 

He did

 

Thanks though Jason

[dat2kman]

Hmm, i'm thinking Dusty's old car, yep, carbs!

DOH moment, oh well!

 

Efi jobbie? Is the ecu able to be datalogged? To show WOT, partial throttle %'s, fuel duty cycle?. Relative to a time span/seconds count?

It may show up a WOT application, ie exit of Hungry, but fuel duty has not responded situation.

 

What fuel pressure reg is it running,??, in my injected car i have a Malpasi, returns to external surge pot, dont like it, as it is hot on return, but at least pot stays full.

 

Now aware you are injected, yes a surge pot with a 044 driver will ensure you dont get a momentary "starve", mine would, but only on big right hand corners, with low fuel level in tank ( splash and dash - low weight in bum)

[PZG302]

James,

 

Been there done that in my two Zeds i have raced.

 

Cheap solution was to run with at least a half full tank in the 260, and at least a third in the 240 until I was looking at doing one hour races and needed to be able to use pretty much all 60 litres. Then  i went to the 2 litre swirl pot under the floor.

 

The 240 tank was modified with a "pot" welded into the tank, but I still got surge at anything under 1/3 tank. The weight doesn't make that much difference when you are carrying an extra 15 litres.

 

The best place to mount a surge tank is under the floor next to the spare wheel well. It is well protected and out of the way of everything. You are better off getting one made to suit rather than buying an ebay special as they are generally designed to be bolted to a floor and not hung from the floor. Also keeps all your fuel out of the cabin, so a bit safer too.

 

Matt

 

 

[Jk_zeder]

I'm running a Turbosmart reg, simple single in/out job and is rising rate.

 

It's definitely looking like a surge tank fix, time to hit a mate up for a favour

 

Thanks for the helps fellas, I'll let you know how I go.