6 replies to this topic

[1380DominoHT]

Hi all, sorted out a previous problem where the car was tunning really rough but now its got another problem!!! It has a problem getting fuel some how, it runs sweet for 10 seconds then it dies a instant death. The carb is at fault im sure, the pot at the side where the fuel goes into seems to overflow after 10 seconds and dumb a bunch of fuel on the ground from the pipe connected to the carb! Iv taken the carb off and inspected the float and there is nothing obstructing it and it moves freely. Iv looked to see if the pipe at the bottom which connects to the bottom of the carb was clogged but it didnt seem blocked at all, im at a real loss folks. Help!

[Jammy]

Sounds like the float chamber is getting stuck.

Either that or you have an aftermarket fuel pump thats supply fuel at way too high a pressure.

[1380DominoHT]

Yea thats what i thought but it moves completly freely when i had it out. Only running a normal mecanical fuel pump. Think there could be a problem with the needle? maybe not moving up to allow more fuel in?

[Jammy]

Have you had the cylinder head off, or removed the engine? What I'm looking for is that the carb has moved near the bulkhead. I once removed the head with the carb still attached and bent the jet, meaning the it would flood the engine constantly.

[dklawson]

Lap or replace the float valve and check the setting of the float itself. It's not a question of whether it moves freely, it's a question of whether it closes and opens. Read your service manual, it will tell you how to adjust the float height.

Several members on this board have suggested lapping the tip of the float valve into its seat using toothpaste. Use the search feature at the top of the page and I'm sure you'll find several threads about this.

Jammy's suggested problem would apply if you were reporting so much flooding that gas was soaking the spark plugs or coming out the intake/exhaust gasket. However, you stated that the fuel was shooting out of the carb overflow which means too much fuel is getting into the float bowl... (i.e. the float valve is not closing for some reason). Again, check the float valve setting and replace/lap as you see fit.

You said you sorted out the rough running problem you posted about the other day. What did you find wrong?

[1380DominoHT]

Yea i there was a really fine crack on the spark plug which wasnt firing properly and the timing which took a bit to get right considering it wouldnt run lol. And there was the tappets which i re adjusted. Everyone was really helpfull, It was probably that plug that was the real problem. Really hard to see without close inspection. Thanks for the info on the carb, i had a look in the manual and i have the type of float that is all plastic and it says to put washers on the needle which i wasnt sure of. What you think?

[dklawson]

I haven't seen that type of float on a Mini... they're generally pretty old over here. However, the method that is employed on similar cars I've worked on is to insert or remove washers between the needle seat and the float bowl cover to get the float gap set right. Is that what your manual is saying?

If you're in doubt about the integrity of your existing part, buy a new float valve to be safe. Or... try the toothpaste lapping first. When you invert the float bowl lid, the weight of the float on the needle valve should be enough to close it off. You shouldn't have to push down on the float to make the valve close.