Club 80-90 Forums

I've got a 2.0 Aircooled, running on original solex carbs and i've noticed lately that the engine smells 'rich' after running for a few mintues and stopping the engine...just kind of got used to it but a friend suggested it was running rich. It uses an electric fuel pump which was fitted before i bought it and i am thinking of fitting a pressure regulator to keep the pressure constant as i heard that electric pumps run at a higher pressure than intended.

A neighbour has a CO2 tester and i decided to test it. It was running at 5% (normal was 1.8%) and haynes suggests 0.6% =/- 0.3%. This to me looks like it is very rich indeed!!!!

The timing is set to 8 degrees ATDC at a steady 865rpm, upon recommendation from Fido Dido of JK forum and was running well with a recent trip at 24 mpg ( which is higher than the original stats from VW) and this has steadily decreased to 21mpg over the past 3 months/ 2k miles.

My questions are:
1. Are the fuel pressure regulators worth it/ necessary?
2. is the timing setting ok?
3. to reduce the CO2 readings is it a simple case to reduce the fuel/ air mix by turning the screw on the top of the near side carb until the readings reduce? Is this something to worry about?

Thanks in advance for any help.

Did you disconnect the engine breather pipe before you took the CO2 readings?

The rich smell after turning off can usually be caused by the fuel in the float chamber overheating and spilling down the inlet manifolds. Usually happens during hotter days. You may notice the engine needs to be turned over a few times more than usual before it will start when it does this due to flooding. Having the accellerator pedal to the floor during cranking will help sort it out!
A fuel pressure regulator could help because the float chamber could be over filling if the pressure into them is too high.

VWCamperfan wrote:The rich smell after turning off can usually be caused by the fuel in the float chamber overheating and spilling down the inlet manifolds. Usually happens during hotter days. You may notice the engine needs to be turned over a few times more than usual before it will start when it does this due to flooding. Having the accellerator pedal to the floor during cranking will help sort it out!
A fuel pressure regulator could help because the float chamber could be over filling if the pressure into them is too high.

thanks - i'll try pedal to the metal when i start....and then fit the regulator at a later date. will let you know how i get on

bigherb wrote:Did you disconnect the engine breather pipe before you took the CO2 readings?

i take it this should be off when testing?

is this the pipe connecting the air filter to the left carb or the pipe from the air filter at the front (nearest the number plate) to the engine block?

might be a dumb point but how old is the air filter - have seen in the past air filters that are like a solid lump... how the engine pulls any air through them when they are like that is a mystery!

Choppski wrote:

bigherb wrote:Did you disconnect the engine breather pipe before you took the CO2 readings?

i take it this should be off when testing?

is this the pipe connecting the air filter to the left carb or the pipe from the air filter at the front (nearest the number plate) to the engine block?

Yes the pipe should be disconnected. The pipe from the air filter at the front (nearest the number plate) to the engine block.
If the CO2 rises significantly when reconnected then the engine oil will need changing.

bigherb wrote:

Choppski wrote:

bigherb wrote:Did you disconnect the engine breather pipe before you took the CO2 readings?

i take it this should be off when testing?

is this the pipe connecting the air filter to the left carb or the pipe from the air filter at the front (nearest the number plate) to the engine block?

Yes the pipe should be disconnected. The pipe from the air filter at the front (nearest the number plate) to the engine block.
If the CO2 rises significantly when reconnected then the engine oil will need changing.

I have changed the air filter about 2 months ago so that should be fine. Thanks for the tip about the breather pipe.

while i'm here....i checked the timing today and it was running at 16 degrees ATDC, so i changed it to the haynes 7 degress BTDC and the engine ran like a fat dog...running sloth like.

So i decided to put it back to 16 ATDC and it ran really perky and sweet.

Now, in case i've read things wrong - ATDC is to the left on the timing scale and thus BTDC is to the right of the zero mark on the scale- is this correct?

When i rev the engine it moves to the left up to 30 degrees ATDC and is very steady.

Running at this timing - are there any issues that this may be masking?

The engine turn clockwises so anything to the left of 0 is Before Top dead Centre and anything to the right is after Top dead Centre

bigherb wrote:The engine turn clockwises so anything to the left of 0 is Before Top dead Centre and anything to the right is after Top dead Centre

what do you set yours at?

big herb - are you also this on the JK forum????

Yes

If yours is POINTS ignition, then set timing to 7.5 degrees BTDC. However, if you have electronic ignition, then you need to set the timing to about 5 degrees ATDC with vacuum pipes connected and at 850 rpm.
You may have looked at the first section in Haynes which describes the setting for points ignition.

VWCamperfan wrote:If yours is POINTS ignition, then set timing to 7.5 degrees BTDC. However, if you have electronic ignition, then you need to set the timing to about 5 degrees ATDC with vacuum pipes connected and at 850 rpm.
You may have looked at the first section in Haynes which describes the setting for points ignition.

thanks - it is electronic ignition.