can't get new carb to idle

[laotsu]

so, I was given a '77 620 KC with an auto transmission. the PO said that it wouldn't idle properly at the last smog check so it never got tested. I dollied it home, found that it ran and drove it aboot 40 miles to PnP. It ran fine with my foot on the gas on the freeway but once I hit the surface streets I found that it would no longer idle and I had to keep my foot on the gas to keep it running. I drove it home and stopped at Pep Boys aboot five miles from my house to get some shit. when I came out twenty minutes later the truck would not start at all. I let it sit overnight and the next day it started but still would not idle. I was able to limp it home. After fucking with the idle adjustments and getting nowhere I tore the carb apart and deciced to order a rebuilt one because throwing new parts at an unknown problem always is the best fix, right? I installed the new carb and it started right up and idled at aboot 1200 rpm until I tapped the gas pedal, then it died. it started and idled again untill it warmed up and the choke opened and I fucked with the idle. Once it was hot it wouldnt even start again.

 

help?

[MicroMachinery]

Is the idle cut-off solenoid functioning properly? That sounds like a problem I was having and it was the culprit.

[banzai510(hainz)]

I tore the carb apart and deciced to order a rebuilt

First mistake.

 

 

Yes try the idle selenoid wire. idle jet plugged with rust. Open the fuel finlter to give a indication of what your dealing with.

mixture. ck the tighnss of the carb.

if no start maybe the float level is too high.

77 might have more emmissions so try plugging more to stuff to bypass.

vaccum leak?

 

 

Is this the mated manifold type intake exhaust? yes I hate those!!!!!!!!!

[datzenmike]

All L20Bs '75 through '77 had the manifolds joined together.

 

Turn ignition on off on off and the solenoid should make a clicking sound.... that's a start.

[ggzilla]

LT, hot wire the idle-cut solenoid to the coil resistor hot side. If that allows it idle let us know.

 

Its on the back under the choke

 

 

Not this one which is bcdd

[laotsu]

Nope hotwiring the solenoid did nothing. I started right up when it was cold and idled for aboot 45 seconds till it warmed up, then I had to give it constant gas or it died.

 

bTW the original carb came with the bccd but the new one doesnt have it.

 

I heard no solenoid click either

[datzenmike]

Does it have the idle cut solenoid like in the picture??? If so remove it but be careful there is a spring and needle in there that may fall out. See if it is stuck.

[laotsu]

has idle cut solenoid, which I pulled from the old carb and it seemed fine. See my problem is that the symptoms are exacly the same from before the carb switch, which leads me to believe it's independent of the carb. Like a vacuum leak or electrical issue. what does the rod on a diaphragm that pushes on the linkage do? it isnt in contact with the linkage and it was on the old carb.

 

I wish I could find a smog legal weber, webers work much better for me.

[datzenmike]

Does it click wen turning the ignition on off on off???? If not this may be the problem and you brought it over from the old carb.

 

Without the idle cut working, fuel cannot get to the idle circuit. Your problem is no idle so....

[laotsu]

No I nnever touched the new carbs Idol solenoid

[datzenmike]

Again...

 

 

Does it click wen turning the ignition on off on off???? If not this may be the problem and you brought it over from the old carb.

 

Without the idle cut working, fuel cannot get to the idle circuit. Your problem is no idle so....

 

Has to click or not likely working.

[ggzilla]

Just take the pintle out of the solenoid and put it the solenoid back on. Then it can't possibly cut the idle.

 

If the problem still happens after that we can talk about other possible causes.

[datzenmike]

Do EEEt

[laotsu]

Gonna have to wait, I am taking greyhoud to Grant's pass to buy another 521 and drive it home. Then I WILL get this idle sorted.

[Georges510]

You might want to check the timing chain, mine skipped a tooth and would no longer idle took it apart and the timing chain was to far stretched. Good luck with your findings.