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#1
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Is this normal for a Q-jet?
I normally run Holleys on my cars but since this particular car is a matching #,s 4 speed 69 GTO Im running a Q-jet on it to keep it original. The problem Im having is if the car sits for more than 2 days the fuel bowl is empty and I have to prime the carb or wear out my starter cranking it to fill it back up. I had sent this carb to Cliff to put in the screw in plugs in the wells so hopefully its not draining out when shut off. My Holley equipped cars can go over a week and still have fuel in them to start.
Is this normal for Q-jets?
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#2
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I have found the same thing with QJs and to a lesser degree with my AFBs.Tom
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#3
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10 seconds on starter may seem like an eternity before start compared to a modern fuel injected car with a closed to atmosphere fuel system and a start button.
Not uncommon with todays fuel evoparates out of fuel bowl in a couple of days. Should not take more than 10 seconds on starter for fuel pump to fill the bowl. I would say normal for a carb with center located small fuel bowl. IIRC this is mentioned in the owners manual. BTW, 1969 and later Q-jets seldom if ever leaks thru the bottom plugs like the 1968 and earlier unit were plagued with. FWIW |
#4
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Quote:
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#5
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My car sits for months and starts rite up. Something is wrong.
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🧩 Burds Parts, Finding those Hard to Find PCs, no Fisher Price Toys Here Just Say No To 8” Flakes pause pause F ire B irds 🇮🇱 |
#6
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With a Quadrajet?
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461 Stroker Built by Me - |
#7
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I installed a small electric inline pump 5 psi That pushes fuel to the original mechanical pump in my 68 GTO. Thought I would need it to ward off vapor lock. But since installed, only use it for 4 second prime before starting. Starter Never cranks more than 4 seconds before starting after a week. No excessive pressure pushing past carb inlet even with both pumps operating.
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#8
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Quote:
Z man, do you recall what electric pump you used? Where did you mount it? Inline or parallel with the fuel line?
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Ed 1968 GTO (Thanks Mom) 2006 Silverado 2007 Cadillac SRX 2015 Chevy Express 2024 Cadillac LYRIQ |
#9
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The pump is mounted above the foward face of the fuel tank on the frame of the car. I cut the fuel feed line there and spliced in the pump. Line in line out. You need to run power to it and have an on/off switch near the dash. Many of the small pumps only put out 5 to 7 psi . they will last eight years or better as you’re not using it constantly . You shouldn’t have to worry about excess pressure forcing fuel past your inlet valve. One pointI should mention if your using this to offset the effects of starvation or vaporlock, you should also install a check valve to force the pressurized fuel to the carb . You can hear my pump ticking as it pumps before startup. Please wrap yours with a hose/ etc if you don’t want the noise.
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#10
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Yes, today's gas will evaporate out of the bowl in a few days. It also has a low temperature boiling point which causes issues with vapor lock and vaporization after switching the car off and trying to restart it after it sits a few minutes. I deal with it with customers constantly with carbureted cars.
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62' Lemans, Nostalgia Super Stock, 541 CI, IA2 block, billet 4.5" crank, Ross, Wide port Edelbrocks, Gustram intake, 2 4150 style BLP carbs, 2.10 Turbo 400, 9" w/4:30 gears, 8.76 @153, 3100lbs |
#11
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I was never able to fix that on my 79 and it got really annoying. I had the plugs in both the big and small wells, the float adjusted, and a new one of Cliff's kits. Nothing helped.
Finally, I went to a Sniper QJ which has been great. Still have to wait for a fuel prime though.
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1979 TATA Extreme TKO .64 Hedman elite; Pypes 2.5; Borla XS; MSD 6A; Edelbrock intake; open scoop; Sniper Q-jet; Powermaster 150; 4 core radiator/Mark VIII fan; RobbMc mini starter; subframe connectors; solid body mounts; fiberglass rear springs; poly sway bar and link bushings; 81 master; D52’s; Blazer disks; 225/60 & 235/60 17's TrueContact's; relays for PW, PDL, lights; keyless entry |
#12
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Yes, the fuel can evaporate over time, but shouldn't take that long to restart. Couple things to check. When you park the car, hot. Take the air cleaner off and look into the carburetor after it sits for 10-15 minutes. If you see fuel dripping out of the center of the venturi, an air bleed is plugged and the bowl is siphoning itself empty. Also look into the manifold below the throttle plates to see if it's wet. Does the car smell like gas when it sits hot?
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The Following User Says Thank You to mgarblik For This Useful Post: | ||
#13
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Quote:
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#14
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I know you are trying to keep the car original, but that issue with QJs is one of the reasons we went to electric fuel pumps on our cars. Just flip the switch for a few seconds and fill the bowl before cranking.
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69 Bird w/1970 400 block(409 cubes), #64 heads, hyd. roller, Q-jet by Jeff E., original interior, ps, pdb, th350, and 3.73 gears. Pump gas, street driven muscle. 3800 lbs. race weight. Best, 11.39 @118, my son's car. 79 T/A w/463, Scat crank, Eagle rods, Icon pistons, Lunati solid roller, 262/270, KRE 325 heads, Northwind intake, QF950 carb, full interior, ps, pdb, th350, and 3.73 gears. Pump gas, 3650 lbs. race weight. 10.68 @ 126 so far... no tuning yet. |
The Following 3 Users Say Thank You to prostreet64 For This Useful Post: | ||
#15
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This 100% - I think ?? ethanol evaporates faster too? I try my best to not run 10%ethanol gas in any old car or power tools/chainsaw.
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#16
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100% gas is readily available in Oklahoma, it's all I use, in everything...
My TA sits for long periods between starts/runs. I turn the key for about 5 seconds WITHOUT touching the gas pedal, then pump the pedal twice, spin engine 5 more seconds. It usually starts. Getting gas to the carb is the first priority... Some folks turn the key and visciously pump the gas pedal, trying to starts. This seems to be a formula for flooding, usually to me...
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1977 Black Trans Am 180 HP Auto, essentially base model T/A. I'm the original owner, purchased May 7, 1977. Shut it off Shut it off Buddy, I just shut your Prius down... |
#17
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Well after I read mgarblik post I took the car for a long drive, after I primed the carb, and got it nice and warmed up. I let it set for 15 minutes and looked down the carb. No dripping. It looked dry. I already thought about an electric pump but Im going to let the next owner deal with it. But I will inform whoever buys it that's its a typical problem with todays fuel and the thimble sized fuel bowl that Q-jets have. The thing that's a bit of a bummer is that of all the Q-jet Pontiacs I have owned this carb runs the best hands down.
Thanks for the replies everyone.
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http://www.machdevelopment.com/album...775/527566.htm |
#18
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I have the same issue with my 68K original mile Can Am, but only on a cold start after it has been sitting for weeks, so I attribute it to the fuel evaporating. Hot starts are no issue.
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Just a blind squirrel looking for a nut. |
#19
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Empty fuel bowl(s) after sitting a few days is normal.
LONG periods of cranking to re-fill the bowl or having to prime it is not. The fuel bowl should re-fill quickly and engine roar to life after 1-2 cycles of cranking for 4-5 seconds. If not there is something else going on keeping the fuel from returning to the fuel bowl. I see this a lot. Could be as simple as a loose hose clamp on a rubber line, or defective mechanical pump, etc.......
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If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
#20
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I had the same problem with my '68 ('74 q-jet) for years until I recently rebuilt it...and I mean to the point that I would get a small bottle and pour gas down the vent tube.
It can now sit for months and it takes no more than 8~10 seconds of cranking. This last build was the first time I decided to re-install the choke as well. I attributed at least some of the change to that.
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Greg Reid Palmetto, Georgia |
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