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Corvair cutting out :/


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Hello all

I have had a 65 Corvair for a little over a year now and its driven amazing up until about a week ago. It will sputter when I drive and often stalls out just sitting at stop lights in neutral (manual) My first thought was a fuel delivery issue but i'm not really sure, i don't have a whole lot of knowledge yet being 17 y/o and no one at home knows old cars. Any help or ideas are very appreciated!

Thank you very much

Ryan 

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Open the chokes on each of the carbs and goose the throttle, are you getting two strong streams of fuel in each carb?  If so, you do not have a fuel issue...  There is a rubber fuel line just inside the DS rear wheel well where the main steel line from the tank attaches to the steel line in the engine compartment.  Is that rubber hose in good flexible shape and not cracked or sucking air?  This is a good place to install an inline fuel filter.  Look at these two things first and report back...  Good luck!  Greg

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1 minute ago, 63RedBrier said:

Open the chokes on each of the carbs and goose the throttle, are you getting two strong streams of fuel in each carb?  If so, you do not have a fuel issue...  There is a rubber fuel line just inside the DS rear wheel well where the main steel line from the tank attaches to the steel line in the engine compartment.  Is that rubber hose in good flexible shape and not cracked or sucking air?  This is a good place to install an inline fuel filter.  Look at these two things first and report back...  Good luck!  Greg

I will check both of those! Thank you

2 thoughts just came up,

If there was a slight fuel delivery problem could the bowls not refill quick enough causing it to die? Also do you know where the fuel filters would be? its the 110hp, 2 carb model

 

Thank you for the help

Ryan

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Sitting idling and cutting out? Cutting out around corners?

 

I would be looking at water in the fuel first. Try some Drygas/Heet. Some of the 60's/70's? Dodges and others had the fuel filler out on the rear fender facing up slightly and were bad about allowing rain in.

 

I've seen people replace carburetors, change fuel filters etc etc and a two dollar bottle of Heet fixed it.

 

My Dad always said "carburetors get 90% of the blame and they are 10% of the cause"

 

-Ron

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 Stock fuel filters are sintered bronze and located just under the carburetor inlet nuts.

 

Unusual to have two clog at the same time. Time to buy tools. Need a 7/16” flare nut wrench for the fuel line and a 1” open end wrench to hold the fuel nut while loosening the line. If you tighten the fuel line without holding the inlet nut, the nut will loosen while driving down the road making a fuel leak, very dangerous! The fuel from the right carburetor will run right past the distributor with all that arcing and sparking going on inside. 

 

But before all that, and after checking for the two streams from the accelerator pumps, check the points clearance, if you are still running points. Typical for them to close up.

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 Vacuum leak can also cause it to lean out particularly at idle. What is it reading ? Vacuum gauges are very handy.

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1 minute ago, John348 said:

I recall reading some TSB's that there was a vapor lock problem in extreme heat, was it really hot out? 

I don't think it would be cracked fuel line that would be an under load situation 

Now that you mention it, its only bad when it gets hot. It is aircooled, that could be it. 

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23 minutes ago, padgett said:

Vacuum leak can also cause it to lean out particularly at idle.

The place for vacuum to leak is the balance tube rubber hoses. They are 3/8” ID about 2” long, one at the base of each carburetor on the forward side.  If loose or making a sucking sound, buy a section of 3/8” fuel line at the store and cut to fit. Might have to remove bolt at the middle of the balance tube to fit them in. Middle as in forward of the center of the fan, where the air cleaner stanchion bolts to the fan housing (Turkey Roaster in Corvair Speak), assuming you  do not have air conditioning, as that is a different air cleaner system on 1965.

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"It happens when it's hot?" if so also check that the vents on the bottom rear of the engine are opening fully, if closed the flow across the heads is restricted. They tend to stick if unused.

(shown closed)

ductflapclosed.jpg

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1 minute ago, Locomobile said:

It starts right back up and runs about the same length of time? And it does this repeatedly? That sounds like a plugged fuel filter, as somebody already suggested above.

I was afraid of that. Yes that description is right on. Corvair fuel filters sound a bit more difficult because theyre built into the carb as Frank DuVal said 

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As Frank wrote, it would be unlikely that both are stopped up and stopping the engine at the same time, one engine bank would still be trying to run (very poorly). There may be another inline filter from the tank, or possibly it's stopped up inside the fuel tank. It sounds like the fuel flow is restricted.

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1 minute ago, Locomobile said:

As Frank wrote, it would be unlikely that both are stopped up and stopping the engine at the same time, one engine bank would still be trying to run (very poorly). There may be another inline filter from the tank, or possibly it's stopped up inside the fuel tank. It sounds like the fuel flow is restricted.

That is true. Its stuttered a few times but recovered almost like one bank is shutting down for a moment. Will inspect both carbs to be safe. Thank you so much for your help! 

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5 hours ago, padgett said:

 Vacuum leak can also cause it to lean out particularly at idle. What is it reading ? Vacuum gauges are very handy.

you really can't set the idle properly on a corvair without a vacuum gauge. you match the readings of each carb to snych the idle speeds of each. good post

 

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3 hours ago, Duff71Riv said:

Corvair fuel filters sound a bit more difficult because theyre built into the carb as Frank DuVal said 

Not at all, young friend. A 1" open-end wrench and a correct-size line wrench (aka flare wrench) makes this a reasonably simple job. Just don't crossthread the fittings or overtighten the filter housing in the pot metal carb, and you'll do fine.

 

You're at the right age to start accumulating tools. Swap meets and flea markets are a good place to find quality tools for not much money. I'm perfectly happy using a well-cared-for older tool, esp if it says MADE IN USA on it!

 

You still got that Riv, bud? For a 17yo you have awesome taste in cars!

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7 hours ago, rocketraider said:

Not at all, young friend. A 1" open-end wrench and a correct-size line wrench (aka flare wrench) makes this a reasonably simple job. Just don't crossthread the fittings or overtighten the filter housing in the pot metal carb, and you'll do fine.

 

You're at the right age to start accumulating tools. Swap meets and flea markets are a good place to find quality tools for not much money. I'm perfectly happy using a well-cared-for older tool, esp if it says MADE IN USA on it!

 

You still got that Riv, bud? For a 17yo you have awesome taste in cars!

Thank you! Yes I do I just did a water pump and radiator on it actually. Thank you for the information I see its easier than I thought. Certainly easier than the 24 pushrod tube seals i did over summer break haha. I have my great grandfathers old tool kit I found in the trunk of the riviera. A lot of hand me downs from parents friends/grandparents friends, they're nice tools tho. Any tool I don't have my auto teacher definitely has, hes taken me under his wing a bit 

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and don't loose the spring behind the filter. A lot of the QJs had the filter there also but are very small. Racers usually left them out and went to the clear plastic ones or large cannister types.

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30 minutes ago, padgett said:

and don't loose the spring behind the filter. A lot of the QJs had the filter there also but are very small. Racers usually left them out and went to the clear plastic ones or large cannister types.

 

POI: Corvair's did not use Quadra-Jets or QJ's as you refer to them. 

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A trick I learned from a GM Zone service manager was, once you got new filters installed at the carb inlet, put an inline filter on suction side of the fuel pump. Catches crud before it gets to the carb filter so those last much longer, and doesn't affect fuel delivery in normal driving. Less you're boogering around with those carb filter inlet housings, less chance of messing up threads and having a leak or worse a ruined carburetor.

 

I use clear plastic ones so I can do visual on them, and they stay full of fuel so I don't worry about starvation. And I'm lucky enough to have never had one plug on me!

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39 minutes ago, John348 said:

 

POI: Corvair's did not use Quadra-Jets or QJ's as you refer to them. 

No, but all Rochester carbs after early 50s had that design fuel filter inlet housing, whether it was paper element, sintered bronze or in case of 4GC, a fine mesh brass screen. I think where Padgett was going is the spring, if equipped, is needed to keep the filter element tight against the filter housing so it doesn't bypass fuel.

 

I bought a reman QJet thru Holley's ProShop years ago. I tore it down for clean/rebuild in late 2017 and found two things that surprised and irked me.

 

Although the inlet spring was there, they had put the short paper filter in a LONG filter housing. No way was that filter not bypassing. I'm convinced the suction side filter kept that carb functioning all those years.

 

2nd thing was I had specified an electric choke as my choke heat tube was toast. That choke never worked well no matter how I set it and in subfreezing temps would never kick off fast idle, after 30 miles or more of driving. Teardown revealed HPS had put an electric choke coil for a 2GC on it, which works opposite the way one for a QJet does. Put the correct choke coil on it and after 17 yrs of half working, that engine cold-started the way it should. 

 

'Course shortly after, the rear end took a dump...

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50 minutes ago, rocketraider said:

I use clear plastic ones so I can do visual on them, and they stay full of fuel so I don't worry about starvation. And I'm lucky enough to have never had one plug on me!

 

I think in this case the easiest thing to do is place a clear in line filter in the system to see if fuel is still being delivered when the vehicle stalls, if so then test for spark. I remember replacing a fuel tank on a Corvair and it was a rather nasty job with a lot of stuff in the way.

Edited by John348 (see edit history)
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Just now, John348 said:

 

I think in this case the easiest thing to do is place a clear in line filter in the system to see if fuel is still being delivered when the vehicle stalls, is so then test for spark. I remember replacing a fuel tank on a Corvair and it was a rather nasty job with a lot of stuff in the way.

It has a new tank and sending unit as of 2019, but I will do that clear filter thats smart, I can see if it flows

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Ryan. While you're checking points etc, look close at the inside of the distributor cap, making sure it's clean, no cracks and no carbon tracks. Remove and wash in hot soapy water if you see anything questionable. A hairdryer will dry it out good before reinstalling. Mark the spark plug cables and firing order before you take it apart to make reinstallation easy. Check the plug cables with an ohmmeter while you're in there; more than 15,000 ohms resistance per foot of length is stretching things with points ignition (and you're increasing your skillset 😎).

 

Then, since you say it's doing this after it heats up, the ignition coil is also suspect as Locomobile mentioned esp if it's the 55 year old original. It can be tested with the ohmmeter. I'm guessing Corvair uses a regular GM 12v external-resistance coil? John or Padgett?

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Try a Fiero: the gas tank is in the console and the pump in the tank. My lift has a 33" wide open space in the middle just in case.

"POI: Corvair's did not use Quadra-Jets or QJ's as you refer to them" Was talking about using the same small filter in the inlet, however my 65 Corsa did have a single QJ replacing the four one-barrels.  Could take heavy cornering on Blue Streaks without missing a beat. Was a popular option back then.

 

ps Yes regular 12v coil. However my last Monza (one with the dual CHTs) had a Pertronix ignition and special coil. Recommended. Periodically am tempted to get another Corsa with 4-speed. Rear engines are cool in hot weather.

 

 

 

 

Edited by padgett (see edit history)
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20 minutes ago, padgett said:

Try a Fiero: the gas tank is in the console and the pump in the tank. My lift has a 33" wide open space in the middle just in case.

"POI: Corvair's did not use Quadra-Jets or QJ's as you refer to them" Was talking about using the same small filter in the inlet, however my 65 Corsa did have a single QJ replacing the four one-barrels.  Could take heavy cornering on Blue Streaks without missing a beat. Was a popular option back then.

 

Are we talking about Fiero's? 

 

So your Corvair was modified?

 

 I am sorry I should have been more clear with my post, GM did not install Quadra Jets on Corvair's 

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Put the fuel filter in the rubber hose connection between the two steel lines just behind the left rear wheel.

 

I install WIX 33032 metal filters in that position. Might have to bend steel lines slightly, but that's usually it. You can run a plastic one there for troubleshooting, but I would replace with metal, since it is subject to road debris flying up there.

 

DO NOT put any rubber lines in the engine compartment. And certainly no plastic fuel filter there. Why? Because when the belt flies off, it will grab the rubber lines, crack open the plastic fuel filter and spill fuel over the hot engine! I've seen the results, NOT pretty!😲

 

Yes, I know, the turbo models have a small 3/16" rubber return line off the factory fuel filter on some models. But this rubber hose and filter is mounted away from everything up next to the firewall and shrouded by air clearer brackets.

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After Padgett said that, I had to go look. The 'Vairs with four barrels were very interesting. Then I found one with SIX carbs, idling at 500rpm and muttering, that snapped the tach from idle to 5k like immediately!🤯

 

I was impressed. Young Ryan- stuff like that is why 17yo should not look at car porn sites!

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13 hours ago, rocketraider said:

Not at all, young friend. A 1" open-end wrench and a correct-size line wrench (aka flare wrench) makes this a reasonably simple job. Just don't crossthread the fittings or overtighten the filter housing in the pot metal carb, and you'll do fine.

 

You're at the right age to start accumulating tools.

 

Yep, what I said.😉 And yes to your warning of crossthreading and stripping the big nut.

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2 minutes ago, Frank DuVal said:

 

The Webbers where you slice the intake manifold off and adapt the triples? They run real good, better than the Quadrajet mounted up in the air. Example:

 

s-l300.jpg

Man that would be cool. I actually have a running 289 from a friends 70 mustang he pulled out and he said i should drop it in the corvair but finding a transaxle adapter and adopting a water cooled engine into it might be difficult. -- fun to think about tho!

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Update: the points cap and rotor look brand new, pretty sure old owner replaced them. After looking at the carbs, the filter replacement doesn't look bad at all! I have two filters and the appropriate gaskets shipping from Mikescorvairparts and bought a clear glass filter for the rubber fuel junction behind the left rear tire as Mr. DuVal said and also purchased a bottle of HEET just in case there is water in the tank. Thank you everyone for your help! 

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