Fuel tank foam movement fouling senders

[John Snook]

I wonder if anyone else has had a similar problem with the foam apparently moving back and forth in the tank under accelleration / braking and in-turn obstructing the free movement of the float type senders.


The fuel readings are thus totally unreliable and I thought someone may have an answer in the form of either;

1. Securing the foam without taking the tanks out/apart !
2. A non-float type sender available to the UK (similar to the Centroid item mentioned in another thread - unfortunately they don't supply outside the USA )
3. Any other ideas?

At present I fill both tanks and drive until the LH tank (36Ltrs) runs dry and from a full RH tank (45Ltrs) I know I'll have 'about' 150 miles before I absolutely HAVE to fill up, but i'ts caught me out once already on the M25 (thanks again Des !).


Any help or advice would be useful, thanks,
John

[JohnMcL]

John,
From Deemon Tweeks website, Level guage systems

Fuel probe (no gauge included) 4-12"/100-305mm. 12-24"/305-610mm. -6 dipstick fitted with alloy cap (up to 300mm tank depth). Please note: Level gauge systems only work with negative earth electrical systems. Sender operates at 240 Ohms empty to 33 Ohms full. Senders can be cut to length and calibrated (by customer) to suit depth of fuel cell.
Rgds
John McL.

[John Snook]

John,
Thanks for the response - amazing what simply changing the word 'sender' for 'probe' can do !
This may be right up my alley.
For your information the ETB fuel gauges i've got accept a signal;

260 ohms empty
20 ohms full

So i'm not sure what effects the 240/33ohm probe will have on the gauge reading (assuming it doesn't blow the gauge!). I will happily accept a small full and empty reading error.
I'll see what Demon Tweeks have to say about compatibility/ mounting style/ wiring etc'.
Out of interest have you used these before?
Many thanks

[JohnW]

Yes John, I've had the same problem in my cobra which is raced regularly. I found the foam would foul the gauge, sometimes jamming it.

I did two things which helped a lot without major modifications:
- I made a aluminium shield mounted to the sender
- Got some long pliers and pinched away some more of the foam to make a recess for the float sender

Whatever you do needs to be resonably strong, as the foam with fuel contained in it is quite heavy.

I'm still not convinced the foam filled tanks are a good thing, as it really did stop fuel surge and was only as good as a baffled tank.

I'm assuming that you have a solid piece of foam in the tank, not the bricks.

[John Snook]

Hi John,
Thanks for the advice, I have already tried to 'secure' the foam internally but my tank orifice is 40mm in diameter so I was limited to what I could acheive by inserting a wire 'frame'.
You have identified the problem with that, in as much that the fuel makes the foam very heavy and there is a good deal of momentum under accelleration/braking so I think what has happened is my wire frame has become deformed once again allowing the float to be contacted..
Internally, the pliers option sounds temptimg but i'd have to become a gynaecologist to perform any such 'operation'
If only the foam had been anchored by the manufacturer I wouldn't be here now
Thanks for the tip - Brisbane .. lovely place - my brother's just returned from 8 yrs living in Kenmore Village.
He owned a new Ford-GT for a time - don't get too excited, it was the Ford Falcon with a 302 shoved in it - but a great drive just the same.
Cheers.
John

[JohnMcL]

Hi John (too many Johns around here),
ETB do a probe sender for their VDO range. Might be worth asking if it will drive the ETB gauge.

No, I have not used one personally, but I know others who have and they have not mentioned problems. Probes also have the advantage that they may be mounted in closed-end tubes with small holes top and bottom to provide some damping.
Rgds
John McL.

[John Snook]

John,
I contacted ETB yesterday, they were most helpful and had some very useful information supplied from (another) John Gere.
The VDO tubes are an option and temping BUT a number of fundamental problems;

• They require a larger hole (42mm) in the tank than there is at present (40mm) so i'd have to drain, remove re-machine etc'.
• The mounting pattern for the 'flange' is 5 hole 54mm PCD as opposed to 6 hole on 60.4mm PCD
• The Tornado tank has the hole for the sender directly over the angled side of the tank, so the sender (if mounted vertically) will foul the side of the tank before it nears the bottom.
• They require new gauges to suit (although ETB can match the old style but with custom internals)

However, on the plus side, the wiring remains unchanged and the VDO tubes have already the small holes for fuel level and so are 'self-damping' regarding the 'sloshing' issue.

The matched set of gauges and 'dip-tubes' may be the way to go, but some inventive mounting may be the order of the day.

I'm hopeful of some technical assistance from Demon Tweeks ref. the fuel 'probes' though.

Thanks again
John