Hard Cold and warm start

[ramayah]

The butterflies will not open and it couldn’t start. With a screw under carb I tighten it and it will open the butterflies a bit and then it will fire up. But I have to give it gas until it warms up. But when eased up on the gas it will die. When I check the carb the butterflies will close.

I felt the two hoses going to the choke assembly and they were cold. Should they be hot to keep the butterflies straight up? If so , why are they not?

So please help ‘ cause I’m going nuts to figure out the problem.

Thanks 

Randy

 

[Hans]

11 minutes ago, ramayah said:

The butterflies will not open and it couldn’t start. With a screw under carb I tighten it and it will open the butterflies a bit and then it will fire up. But I have to give it gas until it warms up. But when eased up on the gas it will die. When I check the carb the butterflies will close.

I felt the two hoses going to the choke assembly and they were cold. Should they be hot to keep the butterflies straight up? If so , why are they not?

So please help ‘ cause I’m going nuts to figure out the problem.

Thanks 

Randy

 

Are you referring to the butterflies on top of the  carb? They are supposed to be closed to start the motor.

[Dudeland]

Randy send some pictures.  I think I know what you mean, but just to clarify. 

[ramayah]

I am referring to the butterflies in the carb. Or flappers?

['76mintgrün'02]

After looking at some of your older posts, I've learned that you have a 32-36 on your '76.  Out of curiosity, did you wind up having it rebuilt back in 2013?  (That price seemed a bit steep to me...).

 

The hoses running to the choke should get warm as the engine heats up.  How long had it been running when you felt them?

 

The flaps should gradually open to the vertical position as this happens.  You are saying that the flaps stay closed even after it has been running?

 

Have you checked the radiator, to make sure the coolant is topped off?

 

There are a few adjustment screws to choose from on the Weber.  Which one are you turning?

 

 

 

 

 

[ramayah]

I didn’t rebuild it in 2013. Yes it’s a 76 with 32/36 Weber.

It ran until the temperature gauge is midway. I stay on the gas until the reaches operating temperature. When I remove my foot from gas pedal it will slowly die.  I immediately checked the carb and the butterflies are closed. Trying to start it back , it wouldn’t start with a warm engine and closed flaps. 

I know they should be perpendicular when warm. That’s the time I checked the hoses to the choke assembly and found them to be cold.

Yes, the radiator has enough coolant.

There is only one screw at the bottom of the carb. From the passenger side, just below the carb. Will send pictures tomorrow.

Thanks.

Randy

 

['76mintgrün'02]

9 minutes ago, ramayah said:

I didn’t rebuild it in 2013.

 

Hmm.  Back then you said it hadn't been done in fifteen years.  You might be due to take it apart to check the floats and give it a good cleaning.

 

So this problem occurred suddenly?  Had it been running well?

 

The flaps should definitely be opening with a warm engine and the choke body/hoses should be quite warm to the touch then too.  If they are not warm, you have identified part of the problem.  I cannot say why coolant would not be getting to the carb, but someone else will surely chime in.  Especially if you bait them with some nice photos.

Tom

[Mike Self]

When the engine is cold, your choke (whether water, electric or manual) performs two functions:  

1. it closes the choke flaps at the top of the carburetor
2. it sets the fast idle cam so your idle is more like 15-1600 rpm vs the normal 800 or so

In order for the above to happen on a cold engine, if you have an automatic choke, you have to "set" it by pressing the accelerator pedal once or twice.  As the engine warms up, the warm water (or electric current) will gradually cause both the choke flaps to open and the fast idle cam to disengage. If this isn't happening, either you have broken or sticky linkages, or the choke is simply inoperative.

 

To check. do this on a cold engine (automatic choke only).  Remove the top of the air cleaner so you can look down the carb's throat.  The choke flaps should be open.  Then while watching down the carb throat, work the accelerator linkage once as if you were flooring the accelerator pedal.  That should cause the choke flaps to snap shut.  If it doesn't, try again.  If they still don't close, remove the air cleaner and lubricate the linkage.  If you still have no action, either the choke itself is not functioning or there's a more serious problem with the linkage. 

 

But if the choke flaps do close, try starting the engine without touching the accelerator pedal. When (if!) it starts, it should be on a high idle (15-1600 rpm or so).  If so, your fast idle cam is working.  If not, the cam linkage or ratchet teeth aren't engaging properly.  Two barrel Solex carbs are notorious for choke failure.  Mine quit functioning when about 8 years old; that's when I switched to a manual choke Weber.

 

Post what you find after doing the above and we'll investigate further.

 

mike

 

PS--this is why I like a manual choke!

 

[ramayah]

Tom, Mile and others,

Before starting I checked coolant level which was low and I filled it up. ( Sorry I told Tom it was enough, it was not.)

The flaps were almost closed. It started right away. Ran it by giving it gas until it was warm. Then it was hesitant to hold idle. I increased idle speed. I am happy now because it wasn’t dying on me. But the flaps weren’t perpendicular as it should. And it stayed that way on a warm engine.

The hoses to the choke weren’t  warm or hot to the touch at all. But it does feel better  than cold. Yet the flaps remained like 60* not 90*.  I shut it off and it started right away. With the gas pedal down the flaps will rise 90 degrees, straight up. After easing off the gas pedal it will return to the usual position of about 60 degrees.

The screw that controls or adjusts the fast idle cam still touches the cam. As I push the cam down and disengages it from the screw the flaps move more freely by hand.

So, now I can have it started, how can I get the flaps up perpendicularly.

[ramayah]

To Mike not Mile.

Sorry

['76mintgrün'02]

Thanks for the excellent photos.  Let's start with this one, which has nothing to do with your choke.   

 

It looks like  you have the large cable coming off of your battery going to the body (strut mount bolt) and a smaller one going over to the alternator. (?)  Is that little black wire to the alternator melted a bit?  Anyway, I think you should put the large cable over on the engine block and have another one between the battery and the fender.  Typically, the alternator has a ground wire running over to one of the little bolts holding the upper timing chain cover.

 

As for the choke adjustment, you can rotate the plates along with the coiled spring that moves them, by loosening the three screws around the outside.  Once loose, you can rotate the hose assembly counter-clockwise to open the flaps more.  You will want to check to see that they still close fully when it is cold though.  

 

I'd keep an eye on the low coolant situation.  I recently learned that the blue BMW coolant leaves a nice chalky residue when it dries.  I think they did that on purpose, so you know when a leak has happened.  The hoses to the choke seem a little oversized on yours and could be leaking.  You might consider replacing those two little pieces with some that fits better.  Or not.  They don't look that bad.

 

The ring that the three screws clamp down on is pretty bent on yours.  You could remove it and flatten it before retightening it.

 

See how it hits outside of the screw, before it actually clamps down on the choke body?

 

Tom

 

['76mintgrün'02]

Another tangent -- When was the last time you changed the coolant?  It loses its corrosion protection as it gets old.  Replacing every two years is recommended, I think.  There could be some nasty buildup in the small fittings that feed the choke coolant hoses, restricting flow and not letting it fully warm up.  Here is a photo that ghubecek recently posted 

 

 

Your idle speed screw looks to be screwed in pretty far.  If it is turned in too far, it opens the bottom butterflies too much at idle and that will pull fuel in through the secondary side's transition hole.(.. or some such thing.  Sorry).  I do know you only want to go 1 1/2 turns or so past where it first makes contact with the lever.

 

Another tangent -- Before doing too much carb adjustment, it is important to make sure the timing is set correctly.  Changes in that area will affect start up and idling characteristics.

 

Tom

Edited January 3, 2020 by '76mintgrün'02
added photo

[ramayah]

Hi Tom  Mike and others,

First off Tom, I will change the coolant and flush it. I don’t remember when the last time I flushed it. Maybe 5-10 years ago.  

The next thing I will replace are the two hoses to the choke with smaller ones.

Then I’ll adjust the flaps so they are perpendicular. (Am I right to say that I must adjust them with the engine is warm)?.

Then I’ll look after the rest of the things you suggested. 

New York is cold now so I will wait until it’s warmer.

I will keep you updated as I go along with the job.

Thanks for your valuable suggestions.

Randy

[Mike Self]

12 minutes ago, ramayah said:

Am I right to say that I must adjust them with the engine is warm

Yes.  And then when the engine is cold and you "set" the choke, make sure they're closed.

 

mike

[ramayah]

Ok Tom. 

When it’s cold and it’s open, say 1/8 in, how to adjust it to make it closed. Do I adjust it with the cam screw below the carb next to the right of the choke?

Or by loosening the 3 choke screws and turn the assembly to make it close.

Thanks. You’ve been of great help and I’m grateful.

Randy