Fuel surge with webers under cornering

[GazM3]

Hey everyone. Tried searching but all the posts on this are for efi. 

Just recently fitted up some grippy Yokahama A021r tyres which work great but it's is causing me fuel surge under the extra cornering loads that the chassis can deliver.

My fuel setup is some dcoe45 webers and one of those box style fuel pumps.   The fuel surge occurs seven with 1/2 a tank of fuel on board.  Do I need to run a dual pump with surge tank or is there any other changes I can make to remedy the situation?  It bogs down and kills power just when u need it   

 

Edited February 14, 2021 by GazM3
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[Son of Marty]

Check to see if the baffle is in place around the fuel pick up. 

[kbmb02]

Check the float level/operation in your carb.

[2002iii]

Might want to get a newer style fuel pump, those old box ones are loud and not know for quality or reliability. I would suggest getting a fuel pickup from an early e30 with the dual pump setup, the intank pump should put out the 3 psi needed for the dual Weber's.

[GazM3]

1 hour ago, 2002iii said:

Might want to get a newer style fuel pump, those old box ones are loud and not know for quality or reliability. I would suggest getting a fuel pickup from an early e30 with the dual pump setup, the intank pump should put out the 3 psi needed for the dual Weber's.

Yes with some research the old box pump is the worst choice.  Ill check the  float and baffle.  May replace with the favoured Carter rotary pump 

[calw]

Don't forget the mount with rubber bushings if that Carter's like the one I had in a car once.  It was hard mounted near the tank in the trunk and reverberated thru the whole car.  Not sure if it was rotary, but the case was cylindrical and a bit bigger than a coffee mug.

[2002iii]

17 minutes ago, calw said:

Don't forget the mount with rubber bushings if that Carter's like the one I had in a car once.  It was hard mounted near the tank in the trunk and reverberated thru the whole car.  Not sure if it was rotary, but the case was cylindrical and a bit bigger than a coffee mug.

The newer ones are smaller and quieter and usually come with rubber mounts included like the kit from Ireland engineering. For extra vibration reduction you can cut an old piece of radiator hose to fit around the pump in the clamp.

[TobyB]

Hmmmm.

 

You say 'surge'- do you mean starvation, flooding under braking, or spillover?

 

The DCOE bowls are truly gigundo-  I can turn the pumps off and still get a pretty 

spirited lap before I lean out and die.

 

So:  what's it doing?

 

Left hand corners making thing rich?  Drag racing running you lean?  Hard braking causing flooding?

 

lotsa things to go 'wrong' with 70 year old technology.

 

Plus, if the bowls are going low on fuel, often you lose one carb as the first one in line takes all the flow.

There's a fantsy manyfold for that one.

 

t

uses dual pickups at the back of the cell and doesn't really have a problem.

 

[GazM3]

Sorry it's more starvation  

[Hans]

35 minutes ago, GazM3 said:

Sorry it's more starvation  

Then I'd heed suggestion to check baffle.

[TobyB]

Ah, starvation.  A big problem in this county, as the rich soak up all the resources.

 

If you're running the stock tank, you CAN add a pot around the bottom of the pickup.

The hard part is figuring out how to keep it in place.  The E30 tanks have a cup of fuel that

tries like heck to keep the bottom of the pickup wet.

 

But honestly, a separate 'make up' tank of a quart or so, and a second pump,

is the easiest way to cure this without cutting things up too much.  The hardest part is finding

a set of low pressure pumps that can fill and pump forward without too much pressure build- up.

Having the top of the make up tank vent off back to the main tank's crucial...

 

and then there's the 'do it all safely' challenge that is a real booger with the 2002.

 

t

 

[2002iii]

The tii's have a small surge canister after the fuel pump, you could try using one of those. 

 

If I remember correctly someone on here had adapted a newer fuel filter with a return to the tank.

 

Most of the newer cars have s bowl/cup around the fuel pickup in the tank. I would see if someone could fab up a cup that you cold somehow attach to the factory fuel pickup and still fit through the factory hole.

 

You can also buy a surge tank setup with a fuel pump inside that you install as close to the gas tank as possible so you don't need 2 pumps.

 

Or like I said above get the fuel pump and pickup from an early e30 and then ad a surge tank.

Edited February 15, 2021 by 2002iii

[Son of Marty]

As Toby said dcoe's hold enough fuel in the float bowls to run for several minutes with out adding fuel makes me think that your problem is not related to starvation but more probably due to fuel slopping into the jet well and it's going terminally rich 

[Oldtimerfahrer]

I have a facett pump and king filter, never have experienced starvation with the DCOEs and I was also running A021Rs on track days... It would have to be a really long bend (I would think) to move the fuel in the tank so far, have the pick up tube and pump run empty, have the King filter fuel bowl run empty, the pipe through the chassis run empty and the sizable DCOE bowls run empty... Maybe your floats are at a minimum anyway and the corners exacerbate the issue?
andrew