edelbrock avs2 650

I have a 89 suburban i converted it over to carbureted it starts fine when cold even at 0F outside but if it sits longer then 10-15 minutes i have to press the pedal down as i am cranking is this normal?

eldebrock 6psi fuel pump with gauge at outlet to confirm its 6psi

eldebrock phenolic spacer

eldebrock air gap

i used braided fuel line and insulated it with aluminum heat wrap tubes witch is good for 800+ degrees

i had a .101 jet with 7342 rod
now i have a .98 jet with 7037 rod

it runs fine even takes off well under acceleration

just gets annoying when you shut it of and then the wife is trying to start it in the drive through and has to start pushing the trottle down while cranking we even try to pump the pedal once before cranking even twice before cranking the only way it will start when hot is pressing the throttle in while cranking

i set my idle mixture screw 3/4 turned out from closed and have 50 mercury on idle

2awg battery cables all new even down to the starter and alternator engine turns over fast!

i figured it was the ethanol causing a boil off but i am now running 92 ethanol free and have been for the last few fill ups and the exhaust seems to to smell a lot better then before buts that’s the only noticeable difference sense changing over

engine was rebuilt has 50k miles with paper work so i know it was actually done hase a crane cam in it as well


if this is normal behavior for a edlebrock carb then i’m not worried about just want to make sure im not missing something

also have a cold case radiator with digital temp gauge the truck runs around 160 in the winter time bellow 30F and summer time 60F-100F the truck will run 180-200F closer to 200 when ac is on and it’s 90F+ out

What symptom is it giving while cranking, Cranking normally,just not starting?cranking slow and you open the throttle to allow it to turn faster? Is the engine warm when this happens? Is the choke open or closed when this happens?

always cranks fast no matter the temperature

Ricko1966 said:

What symptom is it giving while cranking, Cranking normally,just not starting?cranking slow and you open the throttle to allow it to turn faster? Is the engine warm when this happens? Is the choke open or closed when this happens?

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alls ways cranks fast no matter the temperature

choke is open

engine warm

I have the AVS2 on my K5. When the engine ist hot I have to push the pedal a little to get it running. Cold start is 2 pumps and it starts up immediately. I had the same behavior with a 1406 so I think that's normal. The members with more knowledge on carbs will share their wisdom with us.

I always have to push the gas pedal a little to start the truck , even if it's warm. If it's cold i push it to the floor to set the fast idle. It's an Eddy 1406 , pump, and regulator set at 5-6 PSI. If the truck sits more than a few days, I usually have to spray some starting fluid in it to fire her up.

Have run 3 and currently own 2 of the 600 Edelbrock marine versions on 5.7's with dual plane manifolds. They were/are similar to what you describe. They don't require the bump up for choke though as they use a fixed throttle.
Hot or cold, they get 2, 1/2 throttle shots and are started at about 1/4 throttle, then pulled back to idle as soon as they catch. Will probably spin for 5-6 seconds if sitting warm before catching if no shots are given.
The marine versions are all jetted for sea level and have found they like their idle screws set at 1 1/2 turns off their seats, give or take a 1/4 turn.
Not the same model carbs as yours, but similar characteristics.
I currently have one of them in my K30 for break-in this summer.

I have to pump mine about 20 times to start it cold. When it is warm, usually have to pump it a couple of times. It's not fuel injection. 1406, Edelbrock pump, air gap intake. For some reason they just wont hold fuel. I guess it evaporates. So I would say that yours is "normal".

Okay don't know if you can figure a work around after all you've done,but if there's no way to bleed pressure off of the carbureator supply line,when the engine is at rest. The expanding fuel in the line will blow the needle and seat open,over filling the bowl and causing a ricj mixture on a hot start,the extra fuel requires extra air,so you have to open the throttle. To clarify, this is a Qjet problem and I do not know if it is applicable to your AVS. The way I cured it on my qjet was used a factory 3 port pump as a junction,pump itself was inop. and being supplied by an electric pump. Shut your truck off hot,wait a few minutes and crack the line at the carb.see if there's still fuel pressure. If the pumps easy to get to crack line at the pump,don't let the line pressurize,tighten the line back up see if it starts normal then. IDK if you have some sort of return line,but if it was mine,it would, either a 3 port fuel pump or a 3 port fuel filter like a 60s big block nova.

Ricko1966 said:

Okay don't know if you can figure a work around after all you've done,but if there's no way to bleed pressure off of the carbureator supply line,when the engine is at rest. The expanding fuel in the line will blow the needle and seat open,over filling the bowl and causing a Rick mixture on a hot start,the extra fuel requires extra air,so you have to open the throttle. To clarify this is a Qjet problem and I do not know if it is applicable to your AVS. The way I cured it on my qjet was used a factory 3 port pump as a junction,pump itself was inop. and being supplied by an electric pump. Shut your truck off hot,wait a few minutes and crack the line at the carb.see if there's still fuel pressure.

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Interesting theory and makes sense, but doesn't the mechanical pump have a check valve on it's outlet? Just curious.. I am getting the same characteristics with my Edelbrocks whether fed with a mechanical or electric vane.

Buck69 said:

Interesting theory and makes sense, but doesn't the mechanical pump have a check valve on it's outlet? Just curious.. I am getting the same characteristics with my Edelbrocks whether fed with a mechanical or electric vane.

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A 2 port has a check valve and you'll have the same problem,a 3 port will bleed off to the tank.

An old seasoned mechanic told me once that a lot of carburetor problems are electrical.

Just curious, what is your timing set at?

jakewalter said:

An old seasoned mechanic told me once that a lot of carburetor problems are electrical.

Just curious, what is your timing set at?

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A lot of carb tuning problems are actually distributor. You dial in ignition first. Then carbureation

I was just coming on to say what the last 2 have said. Check your timing, too much advance can be hard starting when engine is hot.

Mogulmasher said:

I was just coming on to say what the last 2 have said. Check your timing, too much advance can be hard starting when engine is hot.

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Already covered like post 2. I was clarifying the post above mine for correct order on tuning. But I'm pretty sure he's blowing the needle and seat open on hot soak causing a rich condition

The edelbrocks are notorious for not liking high fuel pressure. 6Psi is the max spec, but really it should be more like 3-4Psi. It must be barely holding on against that 6Psi while running and once it sits long enough to heat soak the fuel line a bit it is flooding it out.