bowl vent leaking gas [Archive] - El Camino Central Forum : Chevrolet El Camino Forums

: bowl vent leaking gas

02-14-2006, 03:04 PM
This is on my original DualJet carb... I rebuilt it not long ago, set everything by the book, and used all new hoses, etc. Today I noticed gas running down the front of my carb. I pulled off the bowl vent hose and had lots of liquid gas spill out. When the car is running there's not gas pouring out or anything like that, but I don't think I should have this much liquid just from splashing. I do have a spring clamp holding the vent hose on tight. Anyone run into this problem before?

02-14-2006, 06:38 PM
The bowl vent is purely a vent. If you have gas leaking from the vent then it sounds like your float is set too high or the needle valve is hanging up and not stopping the flow of gas into the bowl. I know the old Rochester 2V where noted for the needle hanging up and causing flooding.

02-15-2006, 03:33 PM
That's what has me concerned. I know the charcoal canister should not be getting any liquid gas down the vapor line, and so far it hasn't gotten that far because the hoses go over the a/c compressor. After emptying the liquid yesterday, I took it out today and when I got home I only had a drop or two at the top of the vapor hose.

Sorry I forgot to mention this is on my 1980 M2ME carb. I had set the float, and the needle is new. I have not noticed any flooding problems when idling, but I think I may take the air horn off and have a look.

Is it possible I'm getting some spill when I come down a steep hill, like an off ramp?

02-15-2006, 04:54 PM
Is the float sinking? When you pull the air horn, remove the float and shake it to see if there's any gas in it.

02-15-2006, 05:20 PM
No it isn't sinking, it has the plastic/foam type of float. I have also seen it floating just fine, and the fuel level is fine. There's no indication that the float system is failing. I will check again to be sure.

Is the air horn gasket avalable by itself, or can I pull it and then use the same gasket?

02-16-2006, 04:37 AM
The black plastic floats have been known to absorb fuel and become heavy. They will still float but not like they should. Try replacing the float, they are available seperate from the rebuild kit. Also you should be able to reuse the top airhorn gasket.

02-16-2006, 04:23 PM
Thanks for the replies. I'll take a look inside my carb this weekend.

I was thinking possibly the needle clip slipped into one of those holes in the float bracket, or maybe you're right that something has gone wrong with the float. Is there any way to actually check the float, or is seeing it floating at the proper level good enough?

02-16-2006, 04:52 PM
The easiest way to check the float is to have your old one and a new one. You will easily tell the difference in weight when you have them in your hand.

02-17-2006, 11:17 AM
You might be on to something with the old float... since you mention it, I remember when I pulled the carb apart the fuel level was too high and I bent the float bracket back down. Maybe it has taken on some gas and is too heavy, but still floats enough to keep the engine from flooding. I can certainly see how that would mess things up.

I have also noticed the past few months my mileage is bad, and considering it's only a 6 cyl it shouldn't be. Checked or replaced everything else, I didn't think it was the carb since I had already rebuilt it.

The whole plastic float idea is new to me... I'm used to the "real" brass floats that either work or sink :)

02-23-2006, 02:28 PM
I finally got around to replacing the float yesterday. Holding the old and new floats I couldn't tell too much difference, the old one was maybe a little bit heavier.

I set the new float up and took it out for a drive today. What a big difference! The engine runs smoother, responds better, and not one drop of gas in the vapor line after a 45 minute drive. I hope the economy goes up too... I will have to see how that does after my next fill up.

Maybe I'll get a little closer to that EPA estimated 26 mpg :-D

Thanks again for all the replies, I'll never ignore a plastic float again!


02-28-2006, 06:44 AM
"... EPA-estimated 26 mpg..." ??????? They estimated THAT good mileage for an '80 Elky with, what V6, the 229 or 200?? My '79 has the 200 with 3-speed manual and I've yet to break 20 mpg, even on the highway with no hot-dogging at all. It's been a disappointment insofar as fuel mileage is concerned (not to mention gutless, as well). I had to rebuild the carb soon after I got it. It tended to flood out. And dumbshooey here didn't bother to replace the float. Since then, I've continued having problems from time to time, particularly before the carb gets thoroughly warmed up on cold mornings. I have NEVER been able to keep it running when first started without continually punching the pedal, even though the choke seems set right; usually, it stalls two-three times, minimum, before it'll keep running without a foot on the throttle. And in between stalls, it's idling at 1100-1400 rpm. Once I do get it on the road, and before it's completely warmed up, the engine often will bog at low rpm as if the throttle plates are too far open; backing off on the throttle usually gets it to recover and it moves off again.

Also, I've never been able to get the idle speed consistent, and it's usually around 1000-1100 even when fully warmed up. Since this 200 is so gutless, that's sorta good as it keeps me from stalling it when trying to get moving without giving it much throttle from a standstill.

But now, after reading your experience, I bet all my trials and tribulations are due to the plastic float. I just received another '79 carb, same number and all, and will have to rebuild that one, it's so dirty. I'll replace the float on it, too, this time.

One question: when you rebuilt your carb (was its number 17089110, by any chance?? same as my '79, then), did you just leave that little valve-thingy in the fuel bowl and didn't remove it, just like the CSM suggests and the carb kit instructions forget to state?? Or did you count the number of turns as you removed it so you could put it back in the same place?? I counted the number of turns of mine, then flat forgot to write it down :oops: I've since thought that valve to be the cause of my poor mileage and lousy cold temp operating experience.

02-28-2006, 05:45 PM
Yeah, the factory brochure all claimed 26 mpg on the highway. Of course you have to remember in 1980 highway speed was 55 mph. I've never seen any better than 21mpg with my 229 with very careful driving, usually no more than 19 to 20 mpg combined city/highway driving. Kind of dissapointing, I've often wondered if a high-flow air filter would help any. I've done just about everything else--including a new high flow cat and a cold air intake hose... it's still better than my '96 Impala SS on the highway (don't ask about city driving!)

My carb is number ----148, but they're all basically the same. Do you mean the idle air bleed that's in front of the metering rods? No, that is not something I have ever touched. However, that should only affect idle and part throttle mixture, not highway cruising.

I had the same issues starting my 229 before rebuilding everything. Check that the EFE valve works, the ThermAC closes when the engine is cold, that the high idle linkages are not gummed up, and that all the vacuum lines/switches are correct. Also check the choke pulloff. Factory starting procedure is to press gas to floor twice slowly, then crank. It should run at 1700 rpm until you kick it down.

02-28-2006, 06:24 PM
I have an '84 Elky with 229 and TH200C that got 31 mpg on the highway when I first got it a cupla years ago. But it was running super lean at that time. I don't know what it's been getting since I rebuilt the carb a cupla years back, I haven't driven it much due to severe frame rot and my son took it to college most of last year. I believe it's been doing generally around 18 mpg city/highway.

And I've got an '83 Malibu wagon with 229 and TH350C. That's NEVER done better than 17 mpg even on the highway, despite all my tuneup efforts. It's done as poorly as 11 mpg city/highway in cold weather and often only gives around 14 mpg. I've since rebuilt the front end, new tires, and swapped the '84 Elky's 31 mpg carb onto it but then my son took it back to college. No real idea what it's been doing since then.

In comparision, my 1988 Crapice wagon with Olds 307 usually gets no worse than 13 mpg in the coldest weather, even sitting in the parking lot at work during smoke breaks. On the highway, it'll give 21 mpg. In the summer with spirited driving, city/highway mileage goes up to 16-18 mpg depending how many ricers I have to run over :lol:

No, I don't mean the Idle Air Bleed Valve (IABV). On the pre-CCC DualJets, there was a little valve in the bottom of the fuel bowl that's shown in the CSM but I forget what it's called. Dedicated reading of the CSM will eventually unearth the statements that valve is factory-tuned and not to touch it :oops: The CSM gives no instructions whatsoever how to reset it if you do :mad:

Both of my 229s start with a single press of the pedal to the floor. They idle very much like my 1988 Olds 307 except for the increased V6 vibration. But this '79 200 in my Elky is something else entirely. While it starts easily with one press, then goes to 1200 or so, it stays there only a few seconds then dies abruptly, unless you punch the heck outta the pedal. It'll then start immediately without touching the pedal, idle at 1200 or so for somewhat longer, then die again unless you punch it. On the cold mornings we've had these last two weeks, it does that 4 or 5 times and if I try to get it moving outta the driveway, it takes some serious pedal wobbling to keep it going. Yet, the choke is about where it outta be. The pulloff seems to be good but I outta check it again, since this thing backfires sometimes if I punch it too suddenly once it's moving and it's still cold; cudda broken the diaphragm ;o(

EFE valve?? HA. Those rot away on dang near every northern car.

Too dang cold out there to play with anything right now :evil:

On your high-flow air filter: try reversing the lid of the air cleaner to expose the sides of the element :-D That's good for almost half a second in the quarter mile on the big wagon :D

02-28-2006, 06:53 PM
Is there any other adjustment is inside the float bowl? I'm thinking of the one dead center in the bowl, adjustable through a plugged hole in the air horn. That's the one the factory book says never to adjust. I thought it was called the idle air bleed, but I'll have to look again.

The '84 probably did a lot better with CCC controlling the mixture. I have an ad for an '81 Malibu 229 (computer and overdrive) that says EPA esimated 28 mpg highway.

You might try adjusting the choke pulloff just 1 or 2 turns out, so the choke doesn't open as wide right away. That helped a lot on starting mine, I didn't bother with the measured setting. Maybe you need to turn up the fast idle speed screw? Should say on the EPA sticker what to set that to.

I've seen that air cleaner trick before... but then how will I get my temperature controlled air intake? :-D

02-28-2006, 07:21 PM
>Is there any other adjustment is inside the float bowl? I'm thinking of the
>one dead center in the bowl, adjustable through a plugged hole in the air
>horn. That's the one the factory book says never to adjust. I thought it was
>called the idle air bleed, but I'll have to look again.

There are two adjustments that control how far the primary needles can travel: the lean stop screw, and the rich stop screw, which, on later carbs, was combined with the Idle Air Bleed Valve. ALL of these can be accessed through holes in the air horn. If you look back at that web site with the e-Qjet pictures, the first pic illustrates where those access holes are.

Although the CSM states the IABV is factory-adjusted and not to fool with it, Thexton makes a set of CCC carburetor adjustment tools including one with which to reset the IABV, as well as the lean stop screw inside the fuel bowl. Using those gages, you can remove those parts to boil out the carb and rebuild it. And in fact, if you DO NOT remove the IABV and you dunk the air horn into carb cleaner for an hour, the carb cleaner will eat the two rubber O-rings that are on the IABV. Furthermore, NEW O-rings come in every e-Qjet and DualJet carb rebuild kit. So yes, Virginia: even though the CSM states NOT to remove the IABV, you can, and you can install new O-rings on it, and you can reset it using the Thexton gages. Their use is described on that web page:

In fact, carbs that have several hundred thousand miles on them have to have the IABV reset to compensate for wear on its stainless steel pintle valve. This also helps compensate for throttle shaft bushing wear but not entirely. Most e-Qjets I've seen with that many miles could use new shaft bushings installed but I've been able to rebuild a dozen and retune them to acceptable performance, including passing emissions.

>The '84 probably did a lot better with CCC controlling the mixture. I
>have an ad for an '81 Malibu 229 (computer and overdrive) that says
>EPA esimated 28 mpg highway.

DANG.... hard to believe. BTW, the '83 and '84 Malibus and Elkies with 229s were exactly the same, engine-wise. They even used exactly the same carbs, with the same PNs. I have not been able to find any real difference between my '84 and my '83 other than the '84 Elky didn't have AC, while the '83 Malibu wagon did.

Thanks for the tip on the pulloff; I'll just have to try that this weekend. Ain't bout to go out there after I get home at dark in the cold, I'll wait till the sun's up on Saturday :-)

And as for the thermac/reversed lid trick: I don't like to run my lid reversed like that in the winter, anyway, due to all the road sand blowing all over the place. After last winter, my Crapice's engine compartment looked like I'd run the Baja 1000 :evil:

03-01-2006, 10:24 AM
Well no wonder I don't know what you're talking about :-D I've been talking about my M2ME, and you're rebuilding an E2ME! I've never owned a vehicle with an electronic carb, so I can't even begin to guess how the adjustments get made to the mixture limits.

The carb rebuild kit I used had a decimial approximation of the choke opening, I'm sure you know it should be measured with an angle gauge. My engine would start and rev up to 1700 for a few seconds, then stumble and stall. Another crank would get it running fine. I adjusted that choke pulloff a couple turns and that problem hasn't occured since.

I'll have to see what my mileage is like after this week with the new float. I'm kind of aiming to get 22mpg, but that may be too optimistic. I know the heated air cleaner was used to help emissions and driveablility, does heated air also increase economy? I had added the cold air hose which did help summer economy, but the air cleaner sensor will always mix in hot air to keep it 100 degrees. Maybe I would be better off with hot engine air.

I thought all 5th gens shared the A-body platform with Malibu and Monte Carlo, no?

03-01-2006, 06:32 PM
No, I was talking about the M2ME on my '79 200CID Elky. And I ran across the name of that valve in the fuel bowl: APT. Probly means Adjustable Partial Throttle.

I dunno how I got sidetracked into talking bout the electric carbs, other than I'm in three other threads, all of which concern e-Qjets :oops:

Yeah, heated air helps atomize fuel. Raw fuel in the cylinders doesn't burn, it just goes out the exhaust valves without giving up it energy. I'm not a physicist and can't rember my college chemistry but IIRC, at some temperature, because air density decreases with increased temperature (it expands), the amount of oxygen in a given volume of air starts decreasing so again, there's not enough oxygen to combust all the fuel and you're running rich again. That's why racers have to rejet several times throughout a long day as the temperature rises then decreases again at night.

I'm not sure what you're talking bout concerning A-bodies. Ours were called A-bodies until 1983 when GM started calling some FWD body style the A-body and renamed ours, the G-body. It was only a name change, the platforms remained the same. But you do know, right, that the 5th gen Elky has a longer wheelbase than all other A/G-bodies, including the wagons? All the passenger vehicles are 108" but our Elkies are 116". That's the same wheelbase as my fullsized 1988 Crapice station wagon 8O

03-01-2006, 07:09 PM
That sounds like the part... I read about it once somewhere, is that the mixture adjustment for the idle transfer slot? I know it's very critical for emissions, and you're right that the factory manual does not even mention how it gets adjusted.

I've heard similar things about the air temp. The colder the air the denser it is, so with cold air you get more oxygen in the cylinders and can burn more, and get some more power, but then there's the problem with fuel atomization with cold air. I doubt that any of it makes a real difference with a low compression V6, but I did notice the engine ran noticably smoother in hot weather with the cold air intake.

> I'm not sure what you're talking about concerning A-bodies

I was just commenting on the engine combos from when you said:

> the '83 and '84 Malibus and Elkies with 229s were exactly the same, engine-wise

I've never been able to follow all the GM body designations, but I know most of the late '70s and forward Elky, Malibu, and Monte used the same engines, wiring, accessories, etc. Camero and Caprice, too, since they're all covered in the same service manual.