serious CARB question.

[beebster]

My truck ran great, so what do i do? I adjust the HEI,adjust the jets (mixture) and now when i get to 3rd gear it bogs out and dies.
It seems like it's flooding, so i replaced it with another q jet (they are both q jets) and the SAME thing! It bogs out and dies when it reaches third.
Got me pullin my hair out trying to figure it out.
I also noticed the wire to the HEI (Bat.) connector is just jammed in there, no proper connector.

any suggestions?

p. s . Its got an aftermarket (small) fuel filter in the fuel line from fuel pump to carb..

[gonzo6869]

If your are having the same problem with two different Carbs, then you can almost count the Carb itself out. Dose your Q-Jet have an electric choke? Other then 3rd gear dose it seem to be running good? Do you have a fuel pressure regulator? Last one, how old is your fuel pump?

[Sillyoldman]

I'd investigate the possibility of a vacuum leak.

[handsomerob]

As soon as it quits hop out and pull a plug and see what the plug tells ya, rich or lean . . . I'd start there myself.

[beebster]

actually they both ran fine for a few days when first installed, then it seems like they started flooding. I did change the original (rubber) fuel line this spring. I probably put i bigger diameter line, i'm pretty sure.
I'll install a fuel pressure regulator or just buy fuel line tomorrow.
I checked for vacuum leaks and got nothing, i ran it both lean and rich when each q jet was installed until i had em running right, then a couple days later. bogging (flooding i think) always in third.
also noticed when i turned off the truck, it would stay on and stumble and extra 2 seconds.

[gonzo6869]

Like I said before, I doubt that it is your carb, but have you checked the float levels lately. It’s weird that it only happens when you are in third, next time it happen, like said, check one of your plugs, also, take off the air cleaner and check the carb to see if it is still dumping fuel. Next suggestion is, do you still have the old parts from before your upgrades, if you do, you might want to try putting it back together the way it was before and see if your problem goes away.

[gonzo6869]

If you do buy a pressure regulator, go for the cheapest one for now. That way if it doesn't solve the problem, you’re not out much $$. If it fixes it, you can continue to use it, but plan on getting a good one eventually, they run about $75-$100 on up, a cheap one is in the 20's.
A smaller fuel line will not solve a pressure problem, or at least I don’t think it will.

[hilandr452]

Usually when it runs a few seconds after you shut it off, or "diesels", that's an indicator of bad timing. Have you checked the timing?



Dan

[Tkmadone]

I would definitely change out the fuel filter if you haven't already.

[beebster]

Ok now this is strange.
I removed the carb to look inside it, and as i said it's from a 79 corvette.
well, i cleaned it up and put it back on. then i noticed when i tried to start the truck my "pink" wire behind the distributor would catch on fire. Until it finally burned in two.

Well, it's obvious the distributor was wired in bad (as i said in previous post a wire going to "bat" was just shoved up there)
so per instruction on "hei" thread, I removed old "bat" wire and also the wire that ran to the starter.Then ran a 12 volt inline fused wire from "ign unfused" to "bat" and lo and behold problem gone.
truck now runs perfect again.
It seems all this carburator bogging was somehow due to the connection to the distributor.
If someone can explain this "lack" of power or dying in "third gear" because of the bad disributor wiring i'd love to hear it.

highlander452: yes, it was the timing keeping it on an extra 2 seconds, i adjusted and bam! problem gone.

You GUYS are something else, it's like having 10 buddies standing around my motor offering suggestions. Eventually it gets figured out. MUch appreciated.

[highperf4x4]

Actually timing doesn't cause an engine to diesel after you shut it off. Once you kill the switch, the dizzy has no fire. What causes dieseling is excessive carbon buildup in the cylinders from improper fire or poor mixture. The carbon will become a "hot spot" that causes fuel to continue to ignite similar to a diesel engine which fires by heat and compression alone after it starts hence the term "dieseling".

Bad timing or weak fire may have caused the carbon buildup though. One good thing about it is if your engine is dieseling, it usually indicates good compression.

If it starts to do it again in the future you can shut the motor off in gear and then put it into park. Run some Shell Super Unleaded in it for a while and it might help. It has an upper cylinder lubricant and cleaner in it already.

[beebster]

shell sounds like a good idea.
It stopped "dieselling" after i messed with the timing, it was too far advanced.

[highperf4x4]

Originally Posted by beebster

shell sounds like a good idea.
It stopped "dieselling" after i messed with the timing, it was too far advanced.

Yeah but remember, once you shut the switch off, you get no spark because there's no juice to the distributor.

[beebster]

hmmm.
good point.

[shocker]

any chance you had a wire or something else jammed into the mechanical weights of the dizzy preventing the advance from coming on?

[highperf4x4]

Anyway, if it starts dieseling again in the future, don't let it go too long before you pull the heads and clean out as much carbon as you can from the combustion chambers (mostly the valves) and the pistons. This excessive carbon buildup and hot spots are what cause you to burn a valve or a hole in a piston especially when you have a lean condition.

Glad you got your dizzy problem worked out though.