Carter Carb Question AVS

Posted By: Fastfrankie

Carter Carb Question AVS - 07/01/13 10:19 PM

I have a Carter AVS on my 390 AMC engine. When the car sits for a few days, it will not start - it will just crank all day. I then took off the breather and I manually give it the throttle by hand and look down through the carb I do not see any gas squirting. Its not getting gas...

I get a small cup of gas and pour it into the carb and it starts right up and stays running and I'm good to go.

The fuel pump is new, the line is clean, and there is a new filter. I see gas in filter too...so there is gas getting there. The carb is super clean and it was rebuilt a year ago.

Bizarre...could it be something like the needle/seat or float sticks and prevents gas from coming into the carb, but once the engine runs it shakes it loose, allowing gas into the bowl?

Posted By: wannadrag

Re: Carter Carb Question AVS - 07/01/13 10:52 PM

Quote:

I have a Carter AVS on my 390 AMC engine. When the car sits for a few days, it will not start - it will just crank all day. I then took off the breather and I manually give it the throttle by hand and look down through the carb I do not see any gas squirting. Its not getting gas...

I get a small cup of gas and pour it into the carb and it starts right up and stays running and I'm good to go.

The fuel pump is new, the line is clean, and there is a new filter. I see gas in filter too...so there is gas getting there. The carb is super clean and it was rebuilt a year ago.

Bizarre...could it be something like the needle/seat or float sticks and prevents gas from coming into the carb, but once the engine runs it shakes it loose, allowing gas into the bowl?

Not bizarre at all if you google it,it seems to be pretty common.I have a freshly rebuilt AVS and it does the same thing.Soemtimes after a couple hrs the carb will be dry.Some of the problem is the crap gas and some I think is heat soak for me.Did these carbs have any heat barrier between the carb and intake?

Posted By: Cab_Burge

Re: Carter Carb Question AVS - 07/01/13 10:57 PM

Two things may be happening, one is the fuel evaporating and the accelerator pump may be the wrong size, to small

Many of the over the counter cheaper rebuild kits come with the gaskets and accelerator pumps to fit many different carb application so the maufacturer doesn't have to have 12 different kits to fit all the AVS Carter carbs. made for OEM carbs. the other thing to check is the accelerator check valve sticking in the channel under the accelerator pump squirter

Pull the carb. off so you can tip it upside down over a clean white towel or white paper towels to see if it(brass check valve) drops out easily or not

Todays gas with Ethanol in it eats alumminum so it may be stuck in that passage

Posted By: superwrench

Re: Carter Carb Question AVS - 07/02/13 06:18 AM

Accelerator pump or circuit problem...assuming the fuel pump is up to snuff.
Even if the gas evaps over a few days, it should still start after 10 seconds and stabbing at the throttle a few times.
I have an old '54 pickup with a single barrel flathead six in it and the check ball will stick in the accelerator pump well. Sometimes a few good taps with a hammer and away she goes. If it gets started every day or so, it works fine.

Posted By: bigblock340power

Re: Carter Carb Question AVS - 07/02/13 12:32 PM

I'm having a similar problem with my Thermoquad. If I keep the truck in service everyday no problems. But let it sit for a few days/week, and it will not start for a few minutes. Put a cup of gas down the carb, and starts right up. I'm thinking crap gas (Oxygenated to the max, plus additives). Perhaps a weak fuel pump has something to do with it too. I'm going to get a dual action mechanical fuel pump today. I think with the crappy gas now a days, and the old stock fuel pump (that's only a few months old) is just not up to snuff.

Posted By: JohnRR

Re: Carter Carb Question AVS - 07/02/13 01:34 PM

There needs to be a sticky at the top of all forums wit ha tutorial for how and where to install electric fuel pumps ...

Posted By: ademon

Re: Carter Carb Question AVS - 07/02/13 04:43 PM

Quote:

I'm having a similar problem with my Thermoquad. If I keep the truck in service everyday no problems. But let it sit for a few days/week, and it will not start for a few minutes. Put a cup of gas down the carb, and starts right up. I'm thinking crap gas (Oxygenated to the max, plus additives). Perhaps a weak fuel pump has something to do with it too. I'm going to get a dual action mechanical fuel pump today. I think with the crappy gas now a days, and the old stock fuel pump (that's only a few months old) is just not up to snuff.

what's a dual action mechanical fuel pump?

Posted By: JohnRR

Re: Carter Carb Question AVS - 07/02/13 05:44 PM

Quote:

Quote:

I'm having a similar problem with my Thermoquad. If I keep the truck in service everyday no problems. But let it sit for a few days/week, and it will not start for a few minutes. Put a cup of gas down the carb, and starts right up. I'm thinking crap gas (Oxygenated to the max, plus additives). Perhaps a weak fuel pump has something to do with it too. I'm going to get a dual action mechanical fuel pump today. I think with the crappy gas now a days, and the old stock fuel pump (that's only a few months old) is just not up to snuff.

what's a dual action mechanical fuel pump?

Pumps on both the in and out movement of the arm

Posted By: Fastfrankie

Re: Carter Carb Question AVS - 07/02/13 07:33 PM

I attempted to start the car today. Nothing...no gas squirting either. I go take the hose off the carb and gas starts spraying out - there was built up pressure.

I took the top of the carb off and it seems that the needle and seat is sticking. When the float drops, sometimes the needle stays in there. If I blow into the gas port, air only blows out of the other side/float. The needle on the side closest to the drivers side stays in there.

I rebuilt this carb 2 years ago with a Pep Boys carb kit. I just ordered a new Borg Warner kit with new needles/seats.

I don't understand how its sticking - clean as a whistle and not much use at all - no visible wear. Maybe the carb kit was cheap...

Posted By: Moparteacher

Re: Carter Carb Question AVS - 07/02/13 07:46 PM

If the float drops too far the needle can bind. Also, the main wells on the bottom of the carb may be porous.

Posted By: RSNOMO

Re: Carter Carb Question AVS - 07/02/13 07:55 PM

Have you given the sticky N/S a shot of carb cleaner???

Posted By: superwrench

Re: Carter Carb Question AVS - 07/02/13 09:48 PM

I'm gonna throw this in there.......A few years ago I decided to give Aviation 100LL fuel a try. Can't say it helped a lot, but one thing I noticed was that after the car sat for a week or so, I either couldn't get fuel in the bowls, or on the other side of the coin...it would flood. Did some research and came to the conclusion that Av gas is too "Dry".....the needles would stick. Started using 94 pump gas again and the problem stopped. Just saying....