Omega Owners Forum

Chat Area => General Car Chat => Topic started by: MartinP on 20 October 2009, 21:05:30

Title: working out fuel level signal for kit car!!
Post by: MartinP on 20 October 2009, 21:05:30

I have an Omega fuel pump assembly to put into my kitcar fuel tank.

I will be using a seperate fuel gauge on the dash and need to know what signal is coming back from the level indicator and how to use that signal to get a gauge to work.

Gauge has not been purchased yet, I am looking to fit a classic analog gauge so not interested in digi jobs.



Fuel swirl pot
(http://i3.photobucket.com/albums/y99/issunaz/Robin%20Hood/DSCF1991.jpg)


Pump, modified top plate
(http://i3.photobucket.com/albums/y99/issunaz/Robin%20Hood/DSCF1992.jpg)


Fuel level gauge
(http://i3.photobucket.com/albums/y99/issunaz/Robin%20Hood/DSCF1993.jpg)

I am locating the fuel pump unit in the same position in the tank (the bottom) as in the Omega. so the relationship of empty to full should be the same!

I have retained the top plate assembly with the hose & plug connections.

help now needed!!

martin

Title: Re: working out fuel level signal for kit car!!
Post by: Kevin Wood on 20 October 2009, 21:57:00

Are you sure that's going to be resistant enough to surge mounted like that?

With a small tank like that you need all the capacity useable. If running injection you will be better off with a small aluminium sump on the bottom fed through a few holes in the base of the main fuel tank than using the Omega internal pot and pump.

Feed and return lines into the sump so it isn't prone to "sucking air" even when cornering with a practically empty tank, and probably an external filter and fuel pump. - IMHO, of course.

Either that or the arrangement I have - a low pressure fuel pump (facet) feeding an external surge pot which in turn feeds a high pressure pump.

Anyway, regarding the fuel level, you'd be better off getting a sender that matches the gauge, IMHO. However, they are all basically just a variable resistor, that one included, by the look of it. It might have a non-linear response to cope with the odd shape of an Omega tank, I guess.

It also needs to be the right resistance value for the gauge, too.

Try putting a multimeter on ohms across it and work out the min. and max. resistance and try to figure out if it's linear or not.

Kevin

Title: Re: working out fuel level signal for kit car!!
Post by: MartinP on 21 October 2009, 21:48:14

Hi Kev,

See, I knew someone who knew about these things would come along :-)

The pickup on the omega setup is right at the bottom of the pot, with the return pipe feeding into the pot and it positioned on the bottom of the tank on the omega I would have thought that it would work OK.

I will consider my options  :)

Thanks for the other info.

Martin

Title: Re: working out fuel level signal for kit car!!
Post by: Kevin Wood on 21 October 2009, 22:05:36

Can always suck it and see, but the pot will only be as full as the main tank. If it only gives you 100 miles range it will be down to an inch or two for a fair proportion of the time. Add to that something that'll corner a bit more aggressively than an Omega...

There are a few interesting posts on this thread which illustrate both the external surge pot method and what I was thinking in terms of a sump on the tank. :y

http://boardroom.wscc.co.uk/cgi-bin/ikonboard.cgi?act=ST;f=3;t=74660

Kevin

Title: Re: working out fuel level signal for kit car!!
Post by: MartinP on 23 October 2009, 00:25:21

Because I am modifying the tank, i have removed a section with the swirl pot in. I have turned the tank upside down and can make a new swirl pot out of the original filling hole.

I will try to get the omega system to work first (just for the cussedness  ;) ), if it stutters I'll pipe the swirl pot up..

thanks for the links.

Martin

Title: Re: working out fuel level signal for kit car!!
Post by: mrjimbo on 23 October 2009, 04:00:29

VDO do a Fuel gauge for this type of use and it can be used with either a Diptube or an Arm type sender. The Diptube type senders come in various different lengths as well.

Merlin Motorsport at Castle Combe stock them  :y

The seperate swirl pot is the way to go, you can mount it anywhere you have space, it doesn't nessecarily have to be next to the fuel tank which is good as space is often a problem when building kit cars.

Title: Re: working out fuel level signal for kit car!!
Post by: Kevin Wood on 23 October 2009, 09:42:33

This is what I have on my car: http://www.merlinmotorsport.co.uk/p7891/VDO-FUEL-SENDER-SWING-ARM/product_info.html

Of course you could always add an external surge pot fed by the omega pump if it doesn't work.

Another idea: Could you fit a "sump"in the bottom of the tank and drop the Omega pump and pot assembly into it?

Kevin

Title: Re: working out fuel level signal for kit car!!
Post by: I_want_an_Omega on 27 October 2009, 17:10:25

I've got an old Omega instrument panel that you are welcome to have for not a lot, just carve out the bits you want that way ,,

PM me if you are interested.