Cup racer FUEL SURGE - Northy ???

[Evogone]

Had my first event in the cup car at the weekend and went really well. The only negative on the day was a surge problem (I think) cough and splutter then go again, exiting left hand corners from what i can remember. Had a blast on the road and can not get it to do anything.

The petrol gauge swings up and down link nobodies business and i have just read this thread.

http://www.williamsclio.co.uk/forum/...uel+starvation

Was there a solution in the end ?

[evouk]

any pics from the event, how did you get on?

Sounds like you may have to drop some anti surge foam into the car, dont suppose the clio cups had this problem as they were not going round bends that sharp etc etc

[northy]

Hi Steve

I have done 3 trackdays since i first noticed the fuel serge problem. It still hasnt gone away though.

A new fuel sender unit cured one problem i had last year at angelsey. (The sender stuck in the housing which didnt allow the pump too prime) With that changed the car was better - although the spluttering was less it was still there. Long left corners are worse than short ones i noticed.

Initally i cured it by running the car between 1/2 a tank to 1/4 tanks...anything below 1/4 and it started to splutter on a decent left hand bend.

I have been working on the fuel system since feb although i havent used the car for 6months. So far ive washed out the tank (some muck and grit was in so that wouldnt of been helping) fitted a new fuel filter and checked all the wiring.

I have bought a new fuel pump last month that is rated to 500bhp to see if that helps but the problem is caused by the fuel draining away from the pump. not the pump itself. But a uprated one wont hurt.

The standard tank has a kind of baffle as standard but im am suprised to hear yours has the same problem as mine.

If the new pump and clean tank doesnt sort mine i am going to install an aftermarket swirl pot to the car. (Inline after the pump) That will sort the problem out.

Only other modification i may make is to force some fuel foam / sponge into the tank to stop the fuel from moving around so much. I think it happens with cup races due to the light g-force and extra grip of the slicks.

Im not sure if anyone else has had this problem (evouk, richy, bayliss) Carnt ask matbrown as he hasnt driven his yet

The design of the tank isnt the best but i would be suprised if all the mk1 cups suffered this problem when they were racing in 91 - 95. Maybe the removal of the aux tank makes the serge problem worse.
If i was you - buy a swirl pot and fit it to your car. Are you doing croft on the 5th of may ?

[evouk]

yes i have the same problem when below a 1/4 tank...

I think the foam in the tank is the cheaper option

[Evogone]

Has anyone used the foam ? successfully ?

[northy]

not in a standard tank, gaztwo runs the stuffin his tank but thats a custom tank incar mounted.

I am tempted by the foam now while the tank is out but im not sure how much i could get in as the only accsess is on one side of the tank (sender)

Fit a swirl pot mate - then u can tell me if its cured it!

[Evogone]

Will have to do something - foam or swirl pot.

Does your do it when its over half full ?

Anyone fitted a swirl pot ? where in the fuel system does it need to go ?

[northy]

Does your do it when its over half full ?

No - between 1/4 & 1/2

[Evogone]

Is that 2 different options ? Where is that from ?

[teabag]

a swirl pot will definatly solve that problem