Rochester QuadraJet 4bbl Carburetor issue

[Captain J]

Originally Posted by geezer#99

Awesome!
Where in the world do you live?

🤣🤣🤣🤣🤪
I live in a country that temp @6:30 pm is close to 41c?
State of Qatar
However the truck is imported from USA either UT or CO? Among other trucks I own👍🏻

This truck have a loud clunk when in reverse, not sure why?

[geezer#99]

A balmy 16C here this morning. Might get to 25C by end of day.

If you have a two piece driveshaft the clunk could be the centre bearing, or a bad u-joint.

[geezer#99]

If you’re curious about my location!
I live in a little village by the sea!
On the east coast of Vancouver Island. Province of British Columbia.
About 80 km due west of Vancouver across the water.
Very quiet here except for the sometimes fun of a big bird like this. Injured. Couldn’t fly. Eagle rescue caught her. They’ll fix her up and release her.

The clunk you’re getting.
Is your truck 4 wheel drive?

[Captain J]

Originally Posted by geezer#99

If you’re curious about my location!
I live in a little village by the sea!
On the east coast of Vancouver Island. Province of British Columbia.
About 80 km due west of Vancouver across the water.
Very quiet here except for the sometimes fun of a big bird like this. Injured. Couldn’t fly. Eagle rescue caught her. They’ll fix her up and release her.

Wow, nice place & weather.
Beautiful Eagle, good for you, hope she’ll fly

The clunk you’re getting.
Is your truck 4 wheel drive?

Yes my truck is 4x4 K2500 with auto transmission,

[Captain J]

Originally Posted by geezer#99

A balmy 16C here this morning. Might get to 25C by end of day.

If you have a two piece driveshaft the clunk could be the centre bearing, or a bad u-joint.

It’s one piece, I’ll have to check that

[geezer#99]

Could be noise from transfer case.
And sometimes bad motor or trans mounts will make a clunk.

[Dead Parrot]

If it only clunks in 4 wheel drive, suspect the X-fer case or forward drive train.
If it clunks in both 2 & 4 wheel drive, suspect the rear drive train.

Possible that since your idle is fixed, the clunk will largely go away. Even a new drive train has enough slop that switching from D to R or back at high speed can make a noise.

[Captain J]

Originally Posted by Dead Parrot

If it only clunks in 4 wheel drive, suspect the X-fer case or forward drive train.
If it clunks in both 2 & 4 wheel drive, suspect the rear drive train.

Possible that since your idle is fixed, the clunk will largely go away. Even a new drive train has enough slop that switching from D to R or back at high speed can make a noise.

It clunks in 2 WD, only in reverse, it been doing this long before the issue with the carb.

[geezer#99]

Is the carb working better?
Does it start right up like you want?

I’ve installed a torque strap a couple times to limit the motor from moving. Whenever put in gear the motor wants to torque to the passenger side.
I used a short chain with a turnbuckle. Attached to the frame and a convenient bolt down beside the power steering pump.
If the clunk goes away then you know something is hitting somewhere.
If you try that don’t leave the strap in place. Your steering can be effected.

[Captain J]

Originally Posted by geezer#99

Is the carb working better?
Does it start right up like you want?
Carb is fine, it needs fine tuning, engine is shaking little bit
It need depressing the pedal twice to start

I’ve installed a torque strap a couple times to limit the motor from moving. Whenever put in gear the motor wants to torque to the passenger side.
I used a short chain with a turnbuckle. Attached to the frame and a convenient bolt down beside the power steering pump.
If the clunk goes away then you know something is hitting somewhere.
If you try that don’t leave the strap in place. Your steering can be effected.

I’m sure it’s something behind the transfer case to the rear differential,
Im waiting for free time so I can diagnose it probably.
Thank you and the other who helped me to fix the issue. 👋🏻.

The only thing is where to fine a NOS or remanufactered carburetor that fits my truck.
🌺🌹🌷💐

[geezer#99]

Why are you looking for a nos one or reman carb?
Does your truck start normally now?
You know. Pump it a couple times to set the choke, fire it up, it runs on a high idle, tap the throttle after a couple minutes, it idles down to normal, put it in gear and off you go.

[Captain J]

Originally Posted by geezer#99

Why are you looking for a nos one or reman carb?
Does your truck start normally now?
You know. Pump it a couple times to set the choke, fire it up, it runs on a high idle, tap the throttle after a couple minutes, it idles down to normal, put it in gear and off you go.

It starts but no high or low idle 🤔

I’ve other trucks, one requires a 800cfm carb, one requires 750cfm
Thanks again

[geezer#99]

I’ve had two Sean Murphy quadrajets. A bit more in price but excellent parts.
And they can restore your original carb for you.
Look around on here.



https://www.smicarburetor.com/

[cadillac_al]

Those electric choke mechanisms die after a while. That's probably all you need.

[geezer#99]

Another place for carbs.


https://nationalcarburetors.com/chev...arburetor_1986

[Captain J]

Originally Posted by geezer#99

Another place for carbs.


https://nationalcarburetors.com/chev...arburetor_1986

Question
What are these relays for?
In the red box above the distributor

[geezer#99]

Maybe you should start a new thread with a better pic or two.
I don’t know but someone else might.

[Captain J]

Originally Posted by geezer#99

Maybe you should start a new thread with a better pic or two.
I don’t know but someone else might.

Good idea
I’ll thanks 👋🏻

[spr85gmc]

saving this post, I am having the same issues.