Carb problem--HELP

[cwb]

Okay, my carb was rebuilt a few months ago by Jim C. but I haven't run it very much because I was rebuilding the head and doing some other stuff. So I finally got it all back together. It runs pretty good, but the problem is starting. Sometimes it starts and sometimes it doesn't. When it doesn't I can give it some gas directly into the carb and it starts fine. I was playing with my choke and noticed it won't close the butterfly all the way with choke fully engaged. I disconnected the vacuum line from the choke breaker and saw that it was holding vacuum which wasn't allowing the butterfly to close. When I took the vacuum off it closed all the way and was able to start with no gas added. What could be making the choke breaker hold vacuum like that?

Could someone give me some advice?

Chris

 

[swank60]

The choke doesn't close all the way. It's supposed to be cracked open a little. I'm pretty sure there's supposed to be vac on that based on temp (could be wrong)

when I had a starting problem like yours, here's what I was able to trace it down to: 1) bad fusable link. 2) vapor lock (fuel in carb would boil out of the bowl) and a bad accel pump - the reason these things were happening was because my carb fan wasn't working and cooling off the carb after shut down. The heat boiled out the carb and dried out the plunger on the accel pump.

 

[Ming89FJ62]

If you're running the choke breaker from the emissions schematic there's suppose to be a VTV between the throttle positioner (TP) port and the choke breaker. Could have installed it backwards - it delays the vacuum/activation of the choke breaker? If so it may not be able to release after a vacuum has been pulled. When I talked to Jim C last year on how to make my 2F run decently after the PO(s) had half-arsed the desmog he told me not to worry about anything but the spark advance and the fuel vapor recovery circuits0 FWIW.

Ming

 

[cwb]

The valve between the choke breaker and the port ont the side of the carb is on there correctly because I switched it around and it didn't work at all. As for the butterfly, I believe Swank60 is incorrect--the butterfly should be completely closed when choke is fully engaged. Like I said, when I release that line from the CB it goes ahead and closes and then will start fine.

 

[swank60]

It sounds like you need to give Jim C a call and see what kind of support he can offer you.

 

[hj60]

I think it's supposed to close completely until the motor pulls enough vacuum to get by the
VTV and pull the choke breaker open. At least that's what mine does.

The first start after cooling down, ie: 1st thing in the a.m., I pull the choke all the way out,
no matter the temperature, dump the accelerator to the floor for about .75 seconds, let up
and crank. If it only sat overnight, it turns over on the 2nd revolution. If it sat more than
overnight, it may start on the 3rd or 4th rev. Thus I assume my choke breaker is functioning
correctly.

 

[Landpimp]

test the pink and violet(forget which one, I think the pink one) BVSV(bi metal vacuume switching valves) on the t-stat housing, one is for the choke opener I recall. when cold the inside port is not open, when warm(about 100) its open, so blow air thru to check when cold and warm.

and you REALLY need the emission manaul for this stuff, that and a peice of hose and a vaccume gauge and pump......(Junks penis pump will work

pic of the valves, tilt head to the right to view

 

[cwb]

Landpimp, I desmogged and never even hooked these back up. Maybe that's the problem.

Thanks for the photo.

CWB