Carter AFB electric choke - heated element fail?

[CCCC]

(Latest problems noted in post #18))
Have never had to fix or replace an electric choke/element. Just removed this carb and cleaned inlets and needle/seat aspects because it would not take in fuel, even with 9 psi from pump (ethanol caused surface build-up on needle valves so they stuck) - re-installed and it fired up and ran great.

BUT, once warmed up it was very rich at idle and stalled. Took a look at the electric choke - it was smoking from under the adjustment cap and the choke baffle was mostly closed. Could the heated element in there have cooked and, if so, why? Would that be common?

With key on, still have 12v to the choke and across the two terminals. Nothing in the wiring was changed during the remove/re-install. Is an element burnout likely? Can a person replace whatever burned, or is a new unit needed?

Thanks for any insight.

[CCCC]

Will pop the cap off the choke mechanism today to see what may have cooked inside there. Still seeking thoughts/experiences with this.

[davepl]

Chokes are smoke operated. They even rhyme, if you notice. But once you let the smoke out they're no good anymore. Sounds like it's replacement time.

That's assuming it smoked like you're saying - if it just shorted "a little" somehow that might prevent it from working properly and heating the element, but that'd be replacement time too.

[Wrenchbender Ret]

Sounds like the coil is not grounding. If it has 2 terms. one should have a wire to ground. If it has one term. the edges of the black cup have to be grounded through the holdown screws.

[geezer#99]

Originally Posted by davepl

Chokes are smoke operated. They even rhyme, if you notice. But once you let the smoke out they're no good anymore. Sounds like it's replacement time.

That's assuming it smoked like you're saying - if it just shorted "a little" somehow that might prevent it from working properly and heating the element, but that'd be replacement time too.

What are you smokin' Dave??
And you owe me another keyboard!
Sprayed my 'puter laughin' so hard!!

[geezer#99]

Originally Posted by CCCC

Have never had to fix or replace an electric choke/element. Just removed this carb and cleaned inlets and needle/seat aspects because it would not take in fuel, even with 9 psi from pump (ethanol caused surface build-up on needle valves so they stuck) - re-installed and it fired up and ran great.

BUT, once warmed up it was very rich at idle and stalled. Took a look at the electric choke - it was smoking from under the adjustment cap and the choke baffle was mostly closed. Could the heated element in there have cooked and, if so, why? Would that be common?

With key on, still have 12v to the choke and across the two terminals. Nothing in the wiring was changed during the remove/re-install. Is an element burnout likely? Can a person replace whatever burned, or is a new unit needed?

Thanks for any insight.

You got too much fuel pressure!
Need a max of 5 psi.
It's flooding is why it idles rich.
And the smoke you saw was fuel vapor weeping thru the vacuum passage in the choke housing.
Fix the flooding and leave the choke alone.

[randy500]

You can just put power and ground to it and watch it heat up and the element unwind...you could also put an ammeter on it while doing so to see the amps it is drawing. 9psi is probably too much fuel pressure and if its flooding now you probably did something wrong with the carb cleaning, check the needle and seat and other carb adjustments such as secondary's hung open a little bit.

[CCCC]

Originally Posted by geezer#99

You got too much fuel pressure!
Need a max of 5 psi.
It's flooding is why it idles rich.
And the smoke you saw was fuel vapor weeping thru the vacuum passage in the choke housing.
Fix the flooding and leave the choke alone.

Thanks, geezer - your experience.insight may be solving a mystery for me. There was smoke coming from the choke chamber as well as from that edge of the carb air horn. It was surprising to read 9 PSI on the pressure gauge when checking the pump. Most of these Chev V8 pumps seem to show about 5, or maybe 6.

This pump came with the truck many years ago so don't know how or why its pressure would be higher than stock. And, the pump/carb/choke combo has worked great until those needle valves stuck and I then cleaned things up in there. But, can see how the better fuel flow into the bowls at higher pressure is enabling the flooding and rich idle.

Other than the gauge reading, how will I be able to tell from a part # etc. if it is a higher output or higher pressure rated pump? Have never seen a mechanical pump with a pressure adjustment on any of these trucks. Absent such adjustment, does a guy change the pump to a stock rated number, or put a pressure regulator in the line between pump and carb? Or, would lowering the float shut-off level in the bowls solve the flooding even with the 9 PSI?

Further advice/info desired. Thanks, again.

[CCCC]

Thanks, randy500 - had gone out earlier and done just as you suggested. Am thinking that the choke element may still be OK. Looks like a float level adjust may be the first logical step - also will check for secondary being too open at rest.

Still not sure what/if to do about the high FP pressure.

Good stuff guys. Other ideas?

[geezer#99]

You need a regulator.
I've seen stock pumps put out 9 psi.
And most others from 6 to 7. Good for a quadrajet but not a afb or eddy type carb. It's the dual needle/seats that is the problem.
Look for a reg that max's at 5.5.
https://www.summitracing.com/int/par...2518/overview/

[randy500]

This regulator is cheaper...you will need a gauge though and some fittings to hook it up.

I have never had a problem with too much fuel pressure on an edelbrock/carter but people do say that.

https://www.summitracing.com/parts/sum-g3032b/overview/

[geezer#99]

Originally Posted by randy500

This regulator is cheaper...you will need a gauge though and some fittings to hook it up.

I have never had a problem with too much fuel pressure on an edelbrock/carter but people do say that.

https://www.summitracing.com/parts/sum-g3032b/overview/

It might be cheaper but a lot harder to control your pressure at the bottom end of it's pressure rating.
THat's why I use ones rated up to 5.5 psi.

[CCCC]

geezer and randy - thanks much - this is the only Carter AFB I've ever had among all of the Q'jets, Edelbrocks and Holleys on these many old trucks, and the first time I've encountered "too high" fuel pump pressure. Plenty too low. Never too late to learn something, and you are teaching.

The Carter worked great for 12 years and now having taken it apart for cleaning, I like it. The dual inlet/float setup was a surprise, but explains why the engine started occasionally running on one bank once the needles became coated/sticky.

We're into a half blizzard this weekend in the high country and it's too cold to stay out in G3 to work on this thing, so I'll get after the pressure regulator and get back here once this thing is up and running. Thanks a bunch.

[CCCC]

I finally got the noted fuel pressure regulator as directed, installed it and started trying to figure out how to set/adjust it. Zero info/instructions came with the regulator. Since it only allows up to 5psi fuel pressure, I started running the adjustment screw inward until the pressure measured 4 psi twice. So, should be good to go - no more overpressure and engine should idle. Not so.

It now starts and runs strong and will idle OK if I set the RPMs up, but have not been able to work the idle mixture screws and idle speed adjuster down to a slow smooth idle - because the engine stops running after about 30 seconds - even at high idle. It simply shuts off as if it has run out of fuel, which I think is happening. When I re-start, there seems to no flooded effect - no smoke from the pipes.

So far, the smoothest idle I have gotten is with the mixture screws about 1 full turn outward from seated. Would 1 turn open seem to be normal for a Carter AFB at 8,000 ft. elevation?

Unless the fuel pump has gone wacky and is putting out 10 psi and then later not putting out enough fuel to run the engine, I am near stumped with my first ever CAFB.

Some of you folks are very experienced and wise on these issues. I will appreciate any info and insight. Thanks.

[geezer#99]

So when it quits after running for 30 seconds does it start right up? Turn the key and it starts or do you crank it a bunch while stomping on the gas pedal?

[CCCC]

geezer#99 - After it quits, I need to pump the pedal about three to five times until it starts - it falters a bit and then will rev up fine if kept at full throttle for a second or two.

[geezer#99]

Look in the carb when it quits.
You might still be flooding a bit.
You shouldn't see any fuel.

[CCCC]

New fuel pump still pegs the pressure gauge at 10 psi, so it may be even higher (Spectra Premium from Rock Auto - they say it is OEM equal. Hah!) However, the newly added pressure regulator will adjust output pressure from 2 to 5 psi. Had it set at 3 and 4 psi today when working on it.

Engine starts and runs easily at speed, but eventually/intermittently drags and acts like it is starving for fuel on acceleration or going uphill (feels like 50% and rough). I can see no evidence of flooding/unburned fuel smoke at exhaust. Temp wants to rise, so I am thinking lean.

And, it will not idle for more than 15 seconds or so (even at fast idle setting). When it dies, a wisp or two of blue smoke comes up through the air horn.

Have done a lot with Quadrajets but this is my first AFB, and am wondering if something wrong was done when I opened/cleaned it back there. Will remove and open it again tomorrow. So, what am I looking for as a problem source?

Might some feed to secondary be clogged? Is there a certain "best" setting for the dual floats to avoid flooding - and starving? Or ???

If you can cite a good article or thread on Carter AFB issues, or have solution ideas of your own, please post 'em. Maybe I should buy a kit and completely rebuild it. Is there a "best" kit and procedure?

Thanks for any thoughts or info. Not a rush job - there are other Chevs here and this one can sit - but winter is coming and a good running K20 can be helpful. Mostly though, I just want to get it "right" again and off my mind.

[geezer#99]

There's two settings for your floats.
Height and drop.
Check your float drop is set right.

What's your timing curve like?
Initial?
Mechanical?

[CCCC]

Once again, thanks geezer. I will go to an AFB write-up and find the proper float height and drop settings, and then set those correctly.

This engine has an HEI dist and ran beautifully for a long time before these fuel issues started, so I have not checked those timing factors for quite a while. Am doubting timing probs - but might this setup have developed some possible serious interactive issues between fuel feed and timing? When next I get it to idle long enough, I will check those.

Cold in that garage this AM - may get the AFB off later today.

[geezer#99]

Just remember that at higher elevations you need to set your float level lower and increase your initial timing.

[paul blair]

CCCC, You might have more than a fuel problem! Check the HEI cap and see what condition the rotor contact is. I have seen the contact completely burnt away causing hard starting and rough running, at least you will know if the cap is good--my 2 cents.

[CCCC]

Thanks geezer and paul - you are both right on.

geezer - We have been here at 8,000 ft. elevation for 18 years and normally I factor that issue into carb float settings - need to get back in there to check everything and correct anything I might have messed up in that cleaning/re-set.

I normally run a bit more advance due to elevation, but seems like the optimal degrees before TDC has varied with the different engines. Paul - certainly will check the rotor contact and other contacts as well when I look into the timing.

Have been trying to get a re-worked C20 going and off the lift (need to drive it to civilization Tuesday for a windshield replacement and tire changes) - that and unusually cold morning/evening temp conditions have taken attention away from this 69 K20 carb (or other) problem.

It's a good thing these are not big issues in life right now. Thanks for your thoughts - will be back here when I know something significant.