Hello,

I have a v8 1972 su carbs and there are two fuel pumps. After running the car on and off during a day trials the engine kept cutting out and running lumpy but this stopped when i switched the second fuel pump on. The next thing i know is the car is over fueling.

Can anybody help me resolve this problem?

Thanks.

Mike.

Could be worn carbs or too much fuel pressure

Thanks guys,

Does this mean i need to change the carbs if so what shall i replace the s.u. set with?

Mike.

There is a valve that lets fuel into the carburettor bowl, that is operated by a float.

You might need to strip the carbs down, clean them out and possibly replace the valve.

Alternatively, you should have an inline fuel filter fitted and you might need a fuel pressure regulator, just to stop the valve getting over-pressurised, which could force fuel through the valve.

When was the last time you checked the dashpot oil level?

With the fuel pressure regulator, you can tee out from the regulator and feed the fuel back to just before the fuel pump, or a fuel return line to the tank.

What fuel pressure do you have? A few psi is all you need.

Are they HIF or HS type?

Hi raving man,

Your imput is most welcome......Thank you.

Well i have just had a look at the system and it goes like this:

live wire from ignition to fuel pump 2. (fuel feed to carbs)
A live wire join from fuel pump 2 to fuel pump1 (fuel feed to pump 2) with a switch between....ie pump 2 on...pump 2 off
Going by this there is no inline fuel regulator and also no electrical solenoid switch.
No i have not checked the oil level.

However there are two overflow pipes one comming from each carb that allow the fuel to fall to the ground......what a waste.

Mike.

Ok,

I checked the dashpots and it looks like there is a lack of oil in them, one more so that the other.
How does this affect the carb?......if so how?......and could this be my propblem?

I can describe my carb set up now:

Each carb has a pipe that goes to the top of the rocker cover.
Another pipe which is open ended and attached to nothing....this is where i loose fuel.
One more pipe which is attached to both carbs and is a continuation of the fuel feed pipe.

There are no other pipes associated with the carbs.

Mike.