What causes the the Q to siphon itself empty..... Ever since I put my motor back in I got to reprime the carb...After It sits a for some time... a week or so plus... Both of my Q's do this... I did put a NOS Lift pump at the time of rebuild... Before the rebuild Im very sure it was a 2 pumps it fired right up.... with the old pump... At first I thought I was evaporating. Then I started my other 67 300 2jet sits for the same amount of time, Even longer like month +++..2 pumps and she fires right up..... I know there is a fuel filter with a one way valve in it..... Never used one.. Im headed to NAPA see if they got one...
Im going to give this a try.. https://www.ecwid.com/store/everyday-performance/Quadrajet-Fuel-Anti-Drainback-kit-p71544525
Oh well looks like snow&rain in the forecast not going to worry about it.. But I think its normal for the Qjet to drain back after a few days of sitting..
I put one of those K&N air filters on my F100, the one with the filter material in the lid as well. Now I have to crank it quite a bit before it fills the bowl up, pretty sure it's evaporating! I realize this is apples to oranges!!
Harold I can see evaporating. I get my gas from Nelson's Across from Les Schwabs. in Arlington.. And IIRC it always started way faster before.... that was 2 years.... Plus its the rainy season.. ah what month isn't it rainy season in this part of the Jordon rd
I don't think I see this with mine. Usually one pump to the floor to set the choke and then crank and it fires. If it's been sitting for weeks it might take 5-10 seconds (I assume this is due to evaporation from the bowl also).
Mine is like that too. After 2-3 days, the fuel in the bowl is gone. I have a squeeze bottle that I keep full of non ethanol fuel. I fill the bowl through the vent.
If it's been sitting for weeks it might take 5-10 seconds I'll buy that answer... reason Its been raining so much here not really driving it on daily type basis.. Maybe I'll just start it Thursday just to start it..
Old service manual indicates that fuel naturally evaporates out of the bowl through the bowl vent after a few days. Also wells can leak. But I have replaced the well plugs with those new ones with rubber gaskets, but didn't see any difference. Also, if you have the fuel return line on an AC car, the fuel can siphon out of the line. If mine sits for a couple weeks, it takes 5-10 secs of cranking to get going.
My Q-jet has been rebuilt twice, 1st time by John Osborne, second time by Jim Weise. Pretty sure the well plugs have been sealed.
What gets me is the 2jet on the 300 motor 2 pumps after sitting for weeks... So I thought I had a problem.. I'll start the motor in the day or 2 see what happens.. Thanks for all the help.
To other Carb motor I got is on the chevy 350 in the boat on it I allways run it out of fuel via a gas shut off valve.... So no comparison there.
Nice I got a few gallons of 87 cornless generator gas... Empty oil quart, Screw on funnel cap off some gear lube jug,, 6'' of vacuum hose.... Im set..
Once the fuel bowl is full, does it start to your satisfaction? After its sat a long time, have you worked the throttle to see if fuel sprays? Ethanol fuel does evaporate easily, you may have a faulty accelerator pump, faulty needle/seat. If it cranks long at any time, could be ignition related (air gap for pick up), maybe the carb isn’t right for your combo. Just throwing ideas out...
