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Another #$^&%$# YH carb problem
Posted by: Tom Turbo ()
Date: February 04, 2018 09:10AM

The problem is my '63 turbo starts and runs fine, but when I shut it off hot it is difficult to restart, acting as if it's flooded. It is possible the fuel is boiling or at least somehow overflowing into the intake? This carb has been rebuilt according to Bob Helm's book so it's possible something is wrong internally but where to look is the question.

If it don't go, chrome it!
Stroker McGurk, 1961.

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Re: Another #$^&%$# YH carb problem
Posted by: steve c goodman ()
Date: February 04, 2018 09:42AM

Do you live in an area that uses oxygenated fuel?

best wishes, Steve
Rear Engine Spec. Inc. Golden, Colo.

1962 spyder 3.0L turbo---1965 Crown V8
1967 monza 110/4---1968 monza 110/4
1971 amante gt 110/4
CORSA/RMC/PPCC

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Re: Another #$^&%$# YH carb problem
Posted by: Tom Turbo ()
Date: February 04, 2018 09:52AM

If oxygenated means alky fuel, yes, 10% alchohol.

If it don't go, chrome it!
Stroker McGurk, 1961.

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Re: Another #$^&%$# YH carb problem
Posted by: MattNall ()
Date: February 04, 2018 09:55AM

No... oxygenated is different than ETHANOL

Oxy fuels boil easier... and run leaner when all is working normal.





MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
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..............................110-PG.................................................Webered-Turbo

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Re: Another #$^&%$# YH carb problem
Posted by: Tom Turbo ()
Date: February 04, 2018 10:03AM

Since I don't run oxygenated fuel it must a a mechanical problem. I he know the choke is fully open since I popped out the air cleaner. I get it started with a shot of starting ethyr but that's not a good solution. I don't know where else to look for a problem outside of redoing the carb.

If it don't go, chrome it!
Stroker McGurk, 1961.

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Re: Another #$^&%$# YH carb problem
Posted by: jjohnsonjo ()
Date: February 04, 2018 11:41AM

I often thought mine was running rich and that's why it wouldn't start when parked a while after being HOT. I have a fuel pressure gauge located on my regulator. One day I noticed there was NO "0" fuel pressure at a hot start. It would take several minutes of fast idle to get fuel pressure as the cooler fuel worked it way back through the return line. Tried two new fuel pumps and checked all the hoses and connections. Solution, add an in line electric fuel pump and run it for a few minutes after a hot start. I also use it for cold starts.

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2013 KIA Optima SX turbo-AKA ZIPPY (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa

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Re: Another #$^&%$# YH carb problem
Date: February 04, 2018 12:00PM

To comply with Federal mandates, most areas use Ethanol as an Oxygen enhancement for gasoline.
So, for most of us the term "oxygenated" means at least 10% Ethanol is added to the gasoline at the refinery. This does make the gasoline less volatile and the jets need to be larger in a carbureted engine.


Dan Davis ~ Pierce County, WA ~ CORSA Western Director + Corvairs NW + North Cascades Corvairs + Corvanatics
1966 Corsa Turbo coupe ~ ~ 1966 140 Corsa ~ ~ 1965 Monza 140/4 'Vert Sierra Tan/Fawn ~ 1964 Monza 'Vert (SOLD) ~ 1960 Monza Ermine White/Red PG ++ ~ 1965 Monza 140/4 Evening Orchid w/ ivory/black interior ~ 1962 Monza Wagon 102/4 ~ 1963 Rampside/Scamper ~ 1963 Red/Greenbrier ~ 1969 Ultra Van #468

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Re: Another #$^&%$# YH carb problem
Posted by: Dan ()
Date: February 04, 2018 01:17PM

When I was having trouble with mine Steve "Guru" Goodman recommended thai I first disassemble it and make sure it has all the correct parts in it. There is a chart in Bob Helt's book that shows all the part numbers for jets, metering rods ect. Mine had a mish mash of parts in it and when I corrected that it ran better than ever before. Another tip Steve gave me was to replace the rubber tube between the turbo and the manifold. Mine was hard as stone and was leaking vacuum. Good luck!

Dan
Chandler, AZ
1966 Corsa Turbo Convertible
[corvaircenter.com]

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Re: Another #$^&%$# YH carb problem
Posted by: Tom Turbo ()
Date: February 04, 2018 01:41PM

Earlier Matt said oxygenated fuel is different than ethanol which was a surprise because methane, for instance, carries it's own oxygen and makes a louder bang.
If I understand your message it agrees with my understanding, but how does that effect my problem with hot starts?

If it don't go, chrome it!
Stroker McGurk, 1961.

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Re: Another #$^&%$# YH carb problem
Posted by: jjohnsonjo ()
Date: February 04, 2018 02:27PM

Boiling point of a liquid. When this carb was designed boiling point for gas was over 300F, todays gas is less than 200F. Now add to that the way our fuel pumps work. They create a partial vacuum to draw gas from the tank. When you reduce the atmospheric pressure that lowers the boiling point even more. Now the pump is trying to suck vapors and then compress them. Add to that the heat that is stored in a turbo engine and a fuel pump sitting right on top of it.

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2013 KIA Optima SX turbo-AKA ZIPPY (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa

Image and video hosting by TinyPic

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Re: Another #$^&%$# YH carb problem
Posted by: jjohnsonjo ()
Date: February 04, 2018 03:04PM

[www.militarytrader.com]

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2013 KIA Optima SX turbo-AKA ZIPPY (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa

Image and video hosting by TinyPic

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Re: Another #$^&%$# YH carb problem
Posted by: steve c goodman ()
Date: February 04, 2018 04:14PM

Reid Vaporization Pressure (RVP). In the 50s/60s it was listed on gas pumps.

These days the oxygen is boiled away by temps after engine shut down and
all that is left is liquid gasoline in the ports/intake runners. Treat your start-up procedure as if the engine is flooded because it is. Open and hold throttle to allow air into the intake system. On my turbo and my customers around here I have them turn off the electric pump during hot start up too. As soon as engine is running turn pump back on of course.

best wishes, Steve
Rear Engine Spec. Inc. Golden, Colo.

1962 spyder 3.0L turbo---1965 Crown V8
1967 monza 110/4---1968 monza 110/4
1971 amante gt 110/4
CORSA/RMC/PPCC

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Re: Another #$^&%$# YH carb problem
Posted by: Tom Turbo ()
Date: February 04, 2018 05:08PM

I'll try holding the unloader open as you suggest. If necessary I'll go to and electric fuel pump. Thanks for the help.

If it don't go, chrome it!
Stroker McGurk, 1961.

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Re: Another #$^&%$# YH carb problem
Posted by: Nickshu ()
Date: February 04, 2018 05:42PM

What works for me is when starting hot or warm first crank the engine for a few revolutions while not touching the gas pedal. This blows excess fuel out. Then press and hold the pedal about 1/3 down and crank until it starts.

The 24 degrees static timing doesn't help on turbo engines. Running the Safeguard ignition system with 20 degrees cranking retard makes a huge difference in hot start for me. Safeguard is sold by American Pi (Ray Sedman).

Nick
_______________________________________________________________________
1964 Monza Spyder Convertible #435 - Rotisserie restored - Check out my restoration thread here: [corvaircenter.com]
Recreational Mechanic/CORSA Member/COG Supporting Member/US Navy Veteran
Northern Colorado, USA



Edited 1 time(s). Last edit at 02/04/2018 05:42PM by Nickshu.

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Re: Another #$^&%$# YH carb problem
Posted by: Tom Turbo ()
Date: February 05, 2018 02:23AM

Since you are at a higher altitude than I am in coastal Texas the procedure may be a little different. What would you suggest for 130 ft above sea level?

If it don't go, chrome it!
Stroker McGurk, 1961.

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Re: Another #$^&%$# YH carb problem
Posted by: jjohnsonjo ()
Date: February 05, 2018 05:24AM

I just hold mine at 1/4 throttle and crank, then let stabilize while holding at a fast idle.

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2013 KIA Optima SX turbo-AKA ZIPPY (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa

Image and video hosting by TinyPic

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Re: Another #$^&%$# YH carb problem
Posted by: Nickshu ()
Date: February 05, 2018 06:25AM

Tom Turbo Wrote:
-------------------------------------------------------
> Since you are at a higher altitude than I am in
> coastal Texas the procedure may be a little
> different. What would you suggest for 130 ft above
> sea level?

I would think if anything it would be harder to start at altitude and easier at sea level.

Is the rest of your engine sorted out perfectly? The YH is pretty sensitive to vacuum leaks, poor compression, etc. Ignition system optimized? As some have said 90% of carburetor problems are electrical.

Another common source of flooding on the YH is a warped accelerator pump cover. Sanding it flat and/or doubling up on the accelerator pump (cutting an extra one to double the outside edges) can solve this issue.

One other thing that can happen on Turbos when hot is if you are using a gas cap that can only vent inwards, but not outwards (any gas cap made after 1970) you can get flooding problems when hot. Especially when the tank is 3/4 full or higher. The pressurized fuel in the tank will force itself back up the turbo fuel return and flood your carb. Get an original fuel cap or drill holes in a new one....or even better disassemble a new one and remove the one way valve. Some new ones are riveted together but the one I got from Clarks just had metal tangs that I just and to bend to get it apart, then reassemble w/ the breather valve removed.

Also check to ensure your fuel return line is clear. If it's blocked this can also cause hot flooding.

Nick
_______________________________________________________________________
1964 Monza Spyder Convertible #435 - Rotisserie restored - Check out my restoration thread here: [corvaircenter.com]
Recreational Mechanic/CORSA Member/COG Supporting Member/US Navy Veteran
Northern Colorado, USA



Edited 2 time(s). Last edit at 02/05/2018 06:31AM by Nickshu.

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Re: Another #$^&%$# YH carb problem
Posted by: Tom Turbo ()
Date: February 05, 2018 03:57PM

Thanks for the good advice. Sure gives me more weekend projects but they might solve the problem.

If it don't go, chrome it!
Stroker McGurk, 1961.

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Re: Another #$^&%$# YH carb problem
Posted by: JimBrandberg ()
Date: February 07, 2018 05:43AM

Sometimes they need an inverted 3/4 float height instead of 5/8. Sometimes the clue is fuel present at the carburetor inlet after you turn the engine off hot, it might dribble down the air cleaner connection onto the shrouding.
Sometimes the WOT choke unloader link needs to be bent to give it some more action. Sometimes there is mayhem or worn parts within the choke housing.
I believe #$^&%$# YH carb is a common name for them but they can often be put right, sometimes it's difficult to charge for all the time it takes.
I usually leave the carb in place and just remove the top when diddling with the float, that 3/8 nut in the back (front of the engine) can be a pesky little bugger.
Of course reducing the amount of fuel available in the bowl could have ramifications at the other end of the spectrum, going lean at WOT high RPM pull under boost isn't good, so some compromise might be necessary.
Jim Brandberg
Isanti, MN
CorvairRepair.com

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