engine and drivetrain Idle Mystery

[Robotin]

1.6L with weber 32/36 manual choke and universal lo pressure fuel pump.

 

 

when cold, my car wont idle on its own. it will just keep cranking until i push my pedal to the floor then it will fire up and i usually will have to warm it up a little before it will idle on its own.

 

 

(when the engine is cold i pull the choke all the way and nothing changes!)

 

 

[Mike Self]

Couple of things to check:

 

1.  Is your manual choke actually operating?  When you pull the choke cable all the way out, are the butterfly valves atop the carb throats closing completely? 

 

2.  Is the fast idle linkage working?  When the choke is on (butterfly valves closed), the idle speed should jump from the normal 7-800 rpm to about 1500 or so.  There's link connecting the butterfly valves with the accelerator linkage to accomplish this.  If that isn't working, then you'll have a stalling condition until the engine warms up.

 

3.  Any vacuum leaks?  Even a small vacuum leak will cause a cold start/idle problem, as it defeats the purpose of the choke (reduce airflow to give a rich mixture to a cold engine.  Check around the cafb base, manifold gaskets and vacuum ports in the manifold and carb.

 

Let us know whatcha find...

mike

[Robotin]

the manual choke is closing, my car has been on jacks with the hood off for acouple months now. the choke closes all the way.

 

usually when i get it to idle, if i close the choke it dies.

 

i will check for vaccum leaks, last time i check i didnt have any but i will check again.

 

 

 

my weber 32/36 i bought second hand, it came off a 2.0L engine, and would it be possible is the jetting could be all wrong?

 

was thinking about buying some smaller jets (thisc ame to me because it seems like the carb will flood easily.)

[KFunk]

the manual choke is closing, my car has been on jacks with the hood off for acouple months now. the choke closes all the way.

 

usually when i get it to idle, if i close the choke it dies.

 

i will check for vaccum leaks, last time i check i didnt have any but i will check again.

 

 

 

my weber 32/36 i bought second hand, it came off a 2.0L engine, and would it be possible is the jetting could be all wrong?

 

was thinking about buying some smaller jets (thisc ame to me because it seems like the carb will flood easily.)

In case you didn't know, that carb has the 'CD prescription' in it for a 2.0L.  A re-jetting is probably in order....  probably smaller ones, yes. 

[Robotin]

In case you didn't know, that carb has the 'CD prescription' in it for a 2.0L.  A re-jetting is probably in order....  probably smaller ones, yes. 

 

 

thank you! i was worried about that? my next question would be what would be a good jetting for my stock 1.6?

[c.d.iesel]

valve adjustment ?

 

and

 

compression test readings ?

[Robotin]

i recently did a 'cold' valve adjustment. my plan for jetting is to take the 'prescription' and just tune for a '1step' down. 

[dbmw2002]

Ditto on Mikes #3 Vacum Vacum Vacum, a regular Hoover Convention

Edited September 13, 2013 by dbmw2002

[mikebontoft]

funny... sounds like my issue. Try cold starting it without pumping the gas (maybe once) and leaving the choke open.

For example, I flooded my engine and had 50psi compression until I cleared it out and put some oil in to seal the rings. Never tried compression after though.

[kyalami]

+1 on checking the jetting.  I have a tii so I don't know what the Weber carb looks like (it's been 15yrs since I've played with one anyway), but I've struggled with the same problem with the carb on my KTM Supermoto.  

 

I'm guessing that your closed throttle circuit is out of whack.... but if it stalls when you close the choke, then it doesn't make sense that you need a smaller idle/pilot jet.  My bike would only start and run with the choke on full, and stalled even when warm when I turned it off.  I solved that problem by installing a larger pilot jet and adjusting the air/fuel screw to make it richer at closed to 1/4 throttle.  Problem solved.  

 

This may be a stupid question, but does the Weber have a standard float?  I'd make sure that is set correctly if it does.  If the float isn't set, you won't have the correct amount of gas flowing through the needle in the low RPM circuit.  Remember that most carb's have various different fuel circuits depending on throttle position, so don't be tempted to mess with the main jets because it sounds like it runs fine with the throttle open.

 

Jason

[Robotin]

what is the best way to check for vaccum leaks?

[KFunk]

what is the best way to check for vaccum leaks?

 

While the car is idling, spray some carb cleaner or starter fluid around the intake tract in various places the gaskets could be leaking.    The spray will get sucked into the engine, and affect the idle (up or down, depending on what you use). 

 

Sorry I'm not much help on the re-jetting issue.  It may require some reading to really understand the stuff.  It's too bad there's no set formula for the 1.6, but on the up-side you get to learn more about carb tuning.  It should be just a matter of buying the a range of jets and testing and tuning.  Off-hand I'm not sure how the air correction and other things come into play on the weber, though.

[Johnson]

If I can remember what jets were in mine, I`ll let you know.  My 1.6 had a 32/36 and ran pretty well.  Now that I have that same carb on a 2L I need to adjust it....

[Robotin]

would b greatly apprecaited!!

 

 

i found out my issue today!! my idle speed adjusting screw it missing!! today i had the car at optimum operating temperature, and when i tried to open to the choke all the way, it would die. i would have to have the choke slightly closed. but it all makes sense now, i have to try and find a new screw....