8 replies to this topic

[ministe]

Hi,

I've been having a bit of trouble getting my car to run correctly. It's a 1990 998 mayfair with a HS4 carb.

I have been trying to get a good setting with the fuel mixture, and felt like I was hitting my head against the wall as everything I tried wasn't doing anything. Today, by accident I disconnected the breather pipe from the carb and the engine just picked up revs and ran better than it has for months.

What could be causing this? Should this pipe be connected to the carb? The pipe leads from the tappet chest.

Also, i have noticed my fuel overflow has no pipe connected to it? Where should this lead it?

Thanks.

[Brams96]

The fuel over flow should go down past the clutch slave cylinder to below the subframe. It's a rubber pipe that goes from the carb to a metal pipe connected to the flywheel housing on a bracket.

[bmcecosse]

You should have that breather pipe connected - to take away the fumes and prevent leaks and nasty smells. Maybe someone has drilled out the hole larger than it should be ?

[ministe]

I think its something to do with the carb. If I block the hole where the breather pipe attaches to the carb with my finger the revs die down again.

[liirge]

Well by unblocking it you essentially leaning the mixture, so if it is running better with it unblocked then perhaps the carb is too rich. It also allows for more air to enter the carb, are you sure your air filter isn't blocked, or a restriction of the inlet to the carburettor.

[ministe]

The air filter wasn't on the car when I was testing it. And I've recently changed the inlet so there isn't anything blocking that.

[liirge]

well then either your engine is puffing something terrible out of the breather or its running far too rich. That would be my first port of call anyway

Edited by liirge, 14 July 2011 - 07:35 PM.

[bmcecosse]

Ahhh - you said it ran better before - of course it will run faster - more air is getting in! Put the pipe back on - and set up the carb properly.

[Brams96]

As a start point on the carb, with the engine off wind the jet adjuster nut up so the jet is flat with the carb body then wind it back down 6 flats of the nut (1 whole turn) This should get you to a good point where you can start the engine then you have to get it set up properly by following a Haynes manual.