PartTimeGenius

When the Vette sits for two or more days without being driven, I have to pump the pi$$ out of it to get it to start. Just wondering if it's just mine or if that's not too uncommon.

Avette4me

Sounds like a automatic choke problem to me. My '80 starts really well - even in 0 degrees.

Due to other problems, I am sending mine to Lars (of this forum) for an overhaul. He comes highly recommended.

page62

It's called carb leakdown. Very common. To fix, you have to remove the carb and epoxy a couple of specific points. Someone else will chime in and provide better instructions than I can.

I didn't know Lars was still doing carb rebuilds...I thought he retired from doing that.

Avette4me

I stand corrected - in fact, I've even read about leak down in the shop manual - shoulda known :bb

Got an e-mail reply from him on Friday - perhaps I better hurry before he quits! :leaving:


[Modified by Avette4me, 5:11 PM 1/13/2003]

lars

There are several causes for the carb to leak down, causing the problem you describe:

1. Leaking primary or secondary well plugs. This is the most often-discussed cause for this, but it's the least common reason. It is actually very UNcommon for the well plugs to leak on a Q-Jet, but they certainly have a bad rap. To test for this, simply pull the carb off the engine and set it on your workbench. Fill the float bowl with fuel (about a shot glass of gas down through the vent tube sticking up in front of the choke). Let it sit for a while, and then look at the bottom of the carb: The primary well plugs are visible between the primary throttle bores and slightly forward. If there's no fuel dripping, the plugs are fine. If the plugs are wet, you need to repair them.

I see people smearing 5-minute epoxy all over the plugs to seal them up. This does not work for more than a few days. With the engine heat making things expand and contract, the epoxy coating quickly cracks and starts leaking again. To positively fix leaking primary well plugs, you need to drill the centers of the plugs out and tap the wells for a 10-32 thread. You then go over to Lowe's hardware and you buy 2 countersunk socket head cap screws ("allen wrench screws"), 10-32 thread x 1/4" long. Coat the threads on these screws with epoxy, and then screw these into the wells. This will positively seal the wells.

But before you do this, check the wells as noted to see if they're leaking - I'll bet they're not...

2. Make sure you have the correct check-valve in-carb filter installed, and make sure your filter spring is not missing. The later-model Q-Jets with a fuel return line from the fuel pump used a fuel filter with a cehck valve to prevent fuel from draining back out of the float bowl, down to the fuel pump, and back through the fuel return line. If you have removed you in-carb filter and installed an in-line filter, you need to fix this: Trash that in-line filter and re-install the correct in-carb filter with the checkvalve. And make darned sure the spring is installed, or the fuel will flow right by the filter.

3. Make sure your needle and seat are in good shape. A leaky needle/seat will allow the fuel to leak back out of the carb.

4. If you have a bad fuel pump with a leaky chack valve, fuel will siphon out of your carb, down the line, and rught back to the tank. If your fuel pump is old, replace it with a good quality stock-type pump.

5. If you have gasoline in your area with Ethanol added "to reduce emissions," you have a problem. Alcohol has a higher vapor pressure than gasoline, so it will readily evaporate out of the vented Q-Jet float bowl after a few days. The ethanol doesn't cause a problem with the new fuel injected cars due to the tank-mounted fuel pump and the lack of a vented float bowl. But these new fuels in our old, vented carbs tends to disappear. Not much you can do about this...

Good luck tracking down the problems. Tag me back if you need assistance.

Turbo-Jet

the next time it sits for 2 days, remove the air horn and see how much fuel is in the bowl. doubt it is evaporating this time of year, so there should be plenty. if not, then the well plugs may be leaking, or the fuel is draining back out the inlet line. i will post a pic of the plugs later tonight.

Yeller81

On my 81 it takes about 3 tries to get it to fire in the mornings when it has sat overnight Give it a few pumps on the accelerator crank a few seconds repeat a couple of times and boom fires right up . This routine is just for the mornings after she has sat all night. Fires right up the rest of the day first try.
Maybe this a Anti Theft feature ????????
Maybe this is a Normal thing .
:steering:

Turbo-Jet

here is my Q-Jet with both sets of fuel well plugs sealed with epoxy. has worked for 2+ years




[Modified by Turbo-Jet, 7:58 PM 1/14/2003]

Scott A

Mine is the exact same way.

SharkByte

My 81 has a similar problem after sitting all night... Pump the gas twice, twist the key and Vrooom, rumble rumble rumble, idle smooths out, shift to reverse to back out of my parking space and she dies. Twist the key and she fires right back up and runs perfect for the rest of the day.

It always dies the first time I shift it into gear each day. Anyone got an idea whats causing that?