Cold Start (Quadrajet)

[firebane]

So my truck has developed another problem which I'm not sure how to describe or look up but essentially what happens is when I start my truck right now I'll push the pedal once to set everything then start it.

When the truck starts it revs itself up to about 3,000rpm and the drops very fast and may catch itself around 800rpm or it will just completely die together.

Any ideas?

 

[Skweegle89]

So my truck has developed another problem which I'm not sure how to describe or look up but essentially what happens is when I start my truck right now I'll push the pedal once to set everything then start it.



When the truck starts it revs itself up to about 3,000rpm and the drops very fast and may catch itself around 800rpm or it will just completely die together.



Any ideas?

Mine was doing the same thing. Electric choke I assume? Loosen the choke screws and rotate the choke counter clockwise a couple clicks. May have to back out your fast idle screw.


Sent from an old rotary telephone.

 

[firebane]

Yeah electric choke. I'm gonna beat the choke off this thing if that is whats doing it.

 

[Skweegle89]

Yeah electric choke. I'm gonna beat the choke off this thing if that is whats doing it.

It's just set too tight. Listen is up and it should fix it.


Sent from an old rotary telephone.

 

[firebane]

It's just set too tight. Listen is up and it should fix it.


Sent from an old rotary telephone.

Choke housing and coil part doesn't fit very well and is probably causing me grief.

I've taken 3 quadrajets given to me and made 1 decent one out of the two. But the decent still has a few quirks and I am doing my best to get it working well as its the rarer 800cfm one.

 

[Quadrajet Power]

The choke housing has vacuum pulling from the carb, so if it is not snug to the body and have the plastic vacuum port in place, you will have a vacuum leak causing you some trouble. Also, make sure you don't have a gasket between the choke thermostat and the choke body. thermostat grounds itself to the main body.

 

[Skweegle89]

I lied. I had to rotate my choke clockwise to get it to stay open. I have been messing with it for an hour and finally fixed it.


Sent from an old rotary telephone.

 

[Quadrajet Power]

I lied. I had to rotate my choke clockwise to get it to stay open. I have been messing with it for an hour and finally fixed it.


Sent from an old rotary telephone.

Now you know why I got confused when we talked the other day. I have built so many of these, and without it in front of me, couldn't remember which way to turn it.

Also for easiest cold/hot start, make sure your air/idle screws are set correctly. If they are too lean or too rich, it can cause some starting issues.

 

[chengny]

Choke pull problem (operator or linkage binding).

This will cause excessively high idle and then a stall due to a rich mix.

Rich Air/Fuel Mixture
If the choke pull-off (unloader) fails to slightly open the choke after the engine starts, the Air/Fuel Mixture will be too rich for continued operation and the engine will stall.