How long does your Q-jet hold fuel in the bowl?

[AuroraGirl]

Then the conversation turns to what fuc$%n wore ain't working. Puter box still workin? Do I have to drop the tank because the fuel pump quit? Which of these cheap ass china made relay fuse thingys broke? etc...etc... Grin.

Oh you’d love the backseat of my Aurora lol

 

[wanderinthru]

Oh you’d love the backseat of my Aurora lol

Would I now? Guess you would have to prove that!!?? Lol.

This tread is useless without pictures.

 

[SirRobyn0]

fuel pump

I have dealt with this problem that actually is intensified by cold weather. IN cold weather I experience pretty much full drain back to the tank and in warm weather it lasts upward a month easy. In the lines. Remember when dry it takes a bit of cranking to get fuel to the carb to then you have to pump to get starteed. can be a bitch in -30 degrees.

What did I do? Not much, I just replaced my fuel filter with a quality one (wix metal) and put a check valve in after the filter
It will still drain back over time but its significantly slower in my opinion
my pump still works fine so i figured to do that. The internal seals probably not so well, it sat dry for years and a lot of stale gas been sitting in it too.

also im a dirty ******* liar, i put the check valve in before my filter. wonder if that makes much difference. hmm..

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also I read that a qjet can have a filter with a check valve if you purchase one (at the base of the carb, the little guy that can be short or long filtration media) but i have not had any experience on this.

Ok I'm going to preface this by saying I only skimmed the responses but I think I can help you out.

This could be a lot things, but you should be able to fix it without anything after market. The Q-jet varied some though the years with emissions so there are some variables. Assuming the welch plugs are sealed up the other thing to look at is the bowl vent. If it's wide open or not connected to the charcoal canister the fuel in the bowl will evaporate off faster.

I do agree that the edelbrock will loose it's fuel a little faster.

With all that said a good fuel pump should be able to put gas in the carb pretty quickly. I've got an old Cadillac that sits for months on end and it's start typically on the first try, cause it's got a good strong pump.

 

[SquareRoot]

I’d like to see EFI fix this:

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LS Swap.

 

[SquareRoot]

Would I now? Guess you would have to prove that!!?? Lol.

This tread is useless without pictures.

 

[Itali83]

Back on topic…..


Look what I got by accident today. A fuel filter for the quadrajet that has a built in check valve. Pretty sweet. I’ll be putting this in soon to try out. I was going to buy an external check valve but no longer need to.

ben.

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[wanderinthru]

Back on topic…..


Look what I got by accident today. A fuel filter for the quadrajet that has a built in check valve. Pretty sweet. I’ll be putting this in soon to try out. I was going to buy an external check valve but no longer need to.

ben.

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Hope it works. Bet you a nickel it don't. Thats a bet I wouldn't mind loosing.

 

[AuroraGirl]

Be careful fram filters are known to catch some shade

 

[C10MixMaster]

In the summer time in AZ the float bowl will go dry from simple evaporation , mine will go dry overnight and I have verified the well plugs do not leak. If your fuel pump is loosing its prime then the pump is bad. The float bowls on a Holley are HUGE compared to a Qjet probably about 10x bigger. So it last about 10x longer.

 

[59840Surfer]

I just run a boost pump full time, as close to the tank as possible. Turn on the key ... hear the pump clatter a few moments and then go silent ... start engine.

The Fram filters with the check valve? We always tossed them out or poked it out of the filter. They were troublesome and hurt stock vehicle performance.

In hot weather the pump on the engine is sucking fuel in hot steel lines at least six feet long with under vehicle heat from the exhaust and radiator fan blowing preheated air under there too ... and that lowers the vapor pressure (boiling point) of the fuel ... so I always found myself on the ragged edge of vapor lock in SoCal and Southern Arizona, so a boost pump was an absolute.

Just sitting in traffic, idling, even the tarmac is radiating egg-cooking heat up under the chassis too. Triple threat!

With check valves in two pumps, the Q-Jet still boils fuel away at shut down and there's always internal leaks (which I may or may not have) ... helping too to dry out the carb, so it's not just a drain back problem.

More than likely it's a lot of the things above, colluding to make starts harder and longer, but drainback ... is likely only in the lines 'cause the columnar suction is broken by the needle and seat so that's not even anecdotal evidence of that happenstance.

I just quit fighting it and with the added boost pump, I think I've minimized crank time and its probably good now as a get away car.

 

[AuroraGirl]

I just run a boost pump full time, as close to the tank as possible. Turn on the key ... hear the pump clatter a few moments and then go silent ... start engine.

The Fram filters with the check valve? We always tossed them out or poked it out of the filter. They were troublesome and hurt stock vehicle performance.

In hot weather the pump on the engine is sucking fuel in hot steel lines at least six feet long with under vehicle heat from the exhaust and radiator fan blowing preheated air under there too ... and that lowers the vapor pressure (boiling point) of the fuel ... so I always found myself on the ragged edge of vapor lock in SoCal and Southern Arizona, so a boost pump was an absolute.

Just sitting in traffic, idling, even the tarmac is radiating egg-cooking heat up under the chassis too. Triple threat!

With check valves in two pumps, the Q-Jet still boils fuel away at shut down and there's always internal leaks (which I may or may not have) ... helping too to dry out the carb, so it's not just a drain back problem.

More than likely it's a lot of the things above, colluding to make starts harder and longer, but drainback ... is likely only in the lines 'cause the columnar suction is broken by the needle and seat so that's not even anecdotal evidence of that happenstance.

I just quit fighting it and with the added boost pump, I think I've minimized crank time and its probably good now as a get away car.

I won’t say I don’t have leaky gas lines because I haven’t looked since I i replaced tank but there was older rubber sections, never know. Bud I don’t smell gas so I didn’t care. But. I did notice a decrease with check valve. Idk

 

[Matt69olds]

Hope it works. Bet you a nickel it don't. Thats a bet I wouldn't mind loosing.

Not to mention the check valves are VERY restrictive.

 

[Matt69olds]

When I had the Q-Jet on my Olds it would start at the touch of the key if it say for a couple days. After 3-4 days (the hotter the weather, the less time) I would have to crank it a few seconds before it would start.

It was definitely a problem with gas evaporation. If you pour a little gas in the vent, it would start immediately. And to verify the well plugs weren’t leaking I pulled the carb and set it on a homemade holding fixture on the workbench. I capped the fuel line fitting, carefully filled the float bowl, snd let it sit overnight. The news paper under the carb was absolutely dry, with no wrinkles or smeared ink from gas dripping.

Another clue that it’s today’s fuel, I could wait until the engine is completely cooled off, then fill the float bowl. As long as the engine was cold and the float bowl was filled I could come back to the car weeks later abd it would start immediately.

What’s strange is my dads 455 Olds powered 81 GMC will start almost immediately, regardless of how long it sits. I don’t understand why, the engine in the truck is absolutely stock, including the huge cast iron intake manifold. I figured the carb sitting on 80 pounds of hot cast iron would evaporate gas far faster than the engine in my car.

 

[59840Surfer]

I'm willing to bet there's a lot to be included in the missing gas theory is the size of the engine compartment.

My K5 has an engine in it that I can stand alongside it and possibly even close the hood too.

It can hold a fuel charge overnight pretty well - but somehow if I try to restart it every 15 minutes or so (I have a reason to do that when I'm dragging trees out of the forest for firewood) - I have a lot of trouble because it always is starting flooded - I can see the black smoke when it finally fires, coming out the tailpipe in my rear view mirror.

What I believe is that the fuel is boiling and filling the intake runners and making it very hard to restart with an extended crank-time.

I know the well plugs are intact and not leaking since I put the TOMCO kit in that carb over 30 years ago and it has always eventually started - like I said I can always fall back on the boost pump --- but pulling firewood, I just wish it could pump the vapors and raw gas back into the tank so it would be easier to start.

btw: this trouble was worse in SoCal no matter the season - although high altitudes over 8K make it a lot worse.

I believe what it all comes down to is the boiling point of gasoline and vagaries of that in different brands and fuel mixes.

 

[Itali83]

Yeah I totally agree with the gas evaporation. Just wondering how long others are getting before extended cranking. I do believe my Holley lasts longer because the bowl is significantly larger than the Q-jet’s.

I’m probably going to add a clickety clackity pump so I can fill the bowl before trying to start. There’s nothing I hate more than having to crank something for a long period when other times it’ll just fire at the touch of the key.

Ben.