Fuel Issue
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Senior User
Joined: Sep 2014
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Fuel Issue
Hey fellas. I'm having a little carb problem. If I drop the hammer down more than a quarter of the way, my truck bogs down. It nearly dies and hesitates. However, if I gently accelerate while driving, it isn't near as bad, though it still happens a little bit. If I have it in park and push the pedal down slowly and smoothly, it winds all the way through the power band like it's brand new. The carb is a replacement I just put on (it didn't do this before, so I know it's the carb) and it is a junkyard edelbrock 1406.
I'm thinking one of the following:
Bad accelerator pump
To Rich
To Lean
My problem is, I don't know much about carbs. Any tips?
I'm thinking one of the following:
Bad accelerator pump
To Rich
To Lean
My problem is, I don't know much about carbs. Any tips?
Posting Guru
Joined: Aug 2010
Posts: 1,761
Likes: 8
From: Knoxville, TN
Is it puffing black smoke out the back? If not, it's probably too lean rather than too rich.
Did you rebuild the carb? Or is it a straight junkyard pull?
If not rebuilt, it's probably got some gummed up passages that are screwing up the mixture.
If rebuilt properly, best guess without further troubleshooting: either the jets aren't right (overall mixture too rich/lean), or the power valve isn't right (not enriching properly at high load). The accelerator pump gives a squirt even when you just barely blip the throttle - it probably isn't responsible for problems that happen only > 1/4 load.
Did you rebuild the carb? Or is it a straight junkyard pull?
If not rebuilt, it's probably got some gummed up passages that are screwing up the mixture.
If rebuilt properly, best guess without further troubleshooting: either the jets aren't right (overall mixture too rich/lean), or the power valve isn't right (not enriching properly at high load). The accelerator pump gives a squirt even when you just barely blip the throttle - it probably isn't responsible for problems that happen only > 1/4 load.
Elder User
Joined: Jan 2014
Posts: 898
Likes: 3
From: Chillicothe, IA
stolen from a site:
"
Q: I can’t get the “Bog” out of my mechanical secondary carburetor what’s wrong and how can I fix it?
The sole purpose of the accelerator pump system is to provide a combustible air/fuel ratio during hard acceleration, especially from idle, for the time it takes the main metering system, via the booster venturi, to respond to the increase in air velocity. When you mash the throttle opening the throttle plates, air responds instantaneously to the pressure drop (vacuum) generated by the engine through the intake manifold. Fuel on the other hand is too heavy and cannot respond as the air does. Assisting the engine during this transition carburetor engineers developed a hydraulic fuel delivery system to push fuel into the slug of incoming air to make a combustible mixture."
Carb Class: Giving the bog the boot
Not familiar with Edelbrock but i would bet there is as much info on rebuilding and tuning an Edelbrock carb as there is Holley.
Google is your friend.
"
Q: I can’t get the “Bog” out of my mechanical secondary carburetor what’s wrong and how can I fix it?
The sole purpose of the accelerator pump system is to provide a combustible air/fuel ratio during hard acceleration, especially from idle, for the time it takes the main metering system, via the booster venturi, to respond to the increase in air velocity. When you mash the throttle opening the throttle plates, air responds instantaneously to the pressure drop (vacuum) generated by the engine through the intake manifold. Fuel on the other hand is too heavy and cannot respond as the air does. Assisting the engine during this transition carburetor engineers developed a hydraulic fuel delivery system to push fuel into the slug of incoming air to make a combustible mixture."
Carb Class: Giving the bog the boot
Not familiar with Edelbrock but i would bet there is as much info on rebuilding and tuning an Edelbrock carb as there is Holley.
Google is your friend.
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Senior User
Joined: Sep 2014
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I don't see any black smoke, so I'll give richening it up a try. It is a straight junkyard carb, but I ran some cleaner through it. I googled/searched the issue, but unfortunately, everyone has a different "fix" for this problem, and nobody seems to agree on the same one. I hate to through parts at a carb that I would like to trade out for fuel injectors in the next couple years, without knowing it will fix it.
Elder User
Joined: Jan 2014
Posts: 898
Likes: 3
From: Chillicothe, IA
I would start with a rebuild. The kits are fairly inexpensive and usually come with most everything you need. My Holley kit came with new power valve, accelerator pump, floar valves and seats, all orings clips and gaskets needed. I bought a diaphragm for the vacuum actuator also just because. Make sure you shot carb cleaner and air through all the little holes to be sure there is no varnish or anything clogging stuff up. If you can let the parts soak in some good cleaner, great.
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