How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask GM Tech (Cam) Your Own Question
GM Tech (Cam)
GM Tech (Cam), Pontiac Technician
Category: Pontiac
Satisfied Customers: 2376
Experience:  GM Grand Master Technician 2007. 14 years experience.
10949255
Type Your Pontiac Question Here...
GM Tech (Cam) is online now
A new question is answered every 9 seconds

I installed a edelbrock 650 cfm carb, ran great 6 months,

Customer Question

I installed a edelbrock 650 cfm carb, ran great for about 6 months, now won't idle, starts up, runs iratic then died out. Another mechanic said the float was stuck, took it off adjusted the float, it was fine, but it still runs iratic then stalls
Submitted: 1 year ago.
Category: Pontiac
Expert:  Gary replied 1 year ago.

Hi there,

I have had many Carter AFB/Edelbrock carbs, so I'll try to help you.

I've seen fuel line debris stuck in the inlet seat, which floods the engine at idle.

Can you remove the lid again, and we will see where we go from here.

Invert the lid, can you blow through the inlet with your mouth? Hear any leak from the seats?

If you do, pull the offending float pin and float, and see if there is fuel line junk in there.

Gary

Customer: replied 1 year ago.
I will try that the first chance I get, I accept that answer, it it doesn't work , then you may suggest something else
Expert:  Gary replied 1 year ago.

Yes, just let me know when you have the lid off.

Gary

Customer: replied 1 year ago.
Ok, it will be a few days ! Thanks , i will let you know.
Expert:  Gary replied 1 year ago.

They are great simple carbs.

I'm sure you'll find an obvious problem and will be easily remedied.

Do you know the float level and drop specs?

Have you got the Edelbrock tuning manual?

Gary

Customer: replied 1 year ago.
No , I don't have the specs, it wasn't in the box when I got the carb, can you give it to me?
Customer: replied 1 year ago.
I got the carb open, going to blow it with air, do as you suggest, will let you know how it turns out
Customer: replied 1 year ago.
I did what you said it starts and idles a little better but it still idles rough, thick clouds of white smoke and stalls out as I attempt to adjust the idle screws , I had taken the screws out and blew them with air pressure but still won't idle and has the white smoke, what else am I missing?
Expert:  Gary replied 1 year ago.

Hi again,

Did you check and set the float levels, 7/16 drill bit works ok for this.

Thick clouds of white smoke? Coolant?

What temperature is the weather where you are?

Here's a copy of your manual:

http://www.edelbrock.com/automotive/misc/tech-center/dl/carb-owners-manual.pdf

Gary

Customer: replied 1 year ago.
It's about 72 degrees, I'm in Houston
Expert:  Gary replied 1 year ago.

Hi again,

Does the engine blow this thick white smoke from the moment the engine starts or takes a little while?

How old is the fuel?

Are the coolant and engine oil levels ok?

If haven't seen the book I attached, it may be worth a read for you.

Gary

Customer: replied 1 year ago.
Smokes fromIt smokes from the moment the engine starts, fuel about 3 weeks old, coolant good, oil good
Customer: replied 1 year ago.
I am reading the Manuel now
Expert:  Gary replied 1 year ago.

Hi again,

Did you check the needle and seat function with the lid off, upside down, blow into the fuel inlet, lift each float a little, listen to the air past the needle, close the float, check the other one.

I would also check for fuel logged floats, possibly through a soldered seam.

While the lid is off, also check the 8 screws that hold the booster venturis in the main body.

You do also understand about taking the primary metering rods out before airhorn removal, and refitting rods after airhorn fitment. Do NOT attempt fitment with rods still fitted to airhorn.

Gary

Customer: replied 1 year ago.
I am familiar with taking out the metering rods first, did that but when I blew I didn't lift the floats , I didn't hear any air escaping when I blew into it. I will lift and lower the floats, should I hear air escaping when I blow when I lift it or lower it?
Expert:  Gary replied 1 year ago.

With the lid inverted (upside down), the floats will shut the needles and no airflow will happen.

Lift the floats at that point and they should weep one at time.

You can also have the lid with the floats hanging down and both needle and seats will be open, lifting one float at time will shut the needle, but difficult to determine if they are leaking with one float still open, don't lift them up too hard, you'll alter the float adjustment AND damage the needle.

Best bet is to take out the float hinge pins, take out the needles, take out the seats, check the inlet passageway for debris, blowout the passageway, reassemble, check floats are straight and not fouling the main body, check float level and drop as per manual.

How about fuel pressure? Have you measured this?

Is the aircleaner lid far enough away from the bowl vents?

Gary

Customer: replied 1 year ago.
I will take out the float hinge pins and go as you have instructed, the air cleaner is good but I how can I check for fuel pressure? Is there special tools required?
Expert:  Gary replied 1 year ago.

If you read within the edelbrock owners manual, it gives some troubleshooting tips.

You could tee a fuel pressure gauge between the fuel pump and carb like this:

I ran my carbs at 6psi.

Let me know how you go.

Gary

Customer: replied 1 year ago.
Ok
Expert:  Gary replied 1 year ago.

Hi again,

Have you had any progress with your carb fault?

Gary

Customer: replied 1 year ago.
No, haven't had a chance to work on it. I'm away from home
Expert:  Gary replied 1 year ago.

Hi again,

Have you had a chance to do as I have suggested above?

Gary

Customer: replied 1 year ago.
I'm still out of town, should be back tomorrow
Expert:  Gary replied 1 year ago.

Ok, I'll await your reply when you're ready.

Gary

Customer: replied 1 year ago.
Ok
Customer: replied 1 year ago.
I did as you suggest , it starts and idles now but still idles rough and there is still the white smoke , like the things going to blow up!
Customer: replied 1 year ago.
Also, I checked the oil, no oil registered but there seemed to be gas on the dipstick, I'm going to change the oil and see if there is gas in it.