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

[Itali83]

What I’m getting at is how many days does your q-jet hold fuel so when you go to start it and pump the throttle, it’s actually squirting fuel? My 82 with a Holley will last literally the better part of a month before I have extended cranking to get fuel to the bowl and accelerator pump. My 86 with an edelbrock lasts just more than a week. So far my 76 with a freshly rebuilt, and epoxied well plugs lasts about 3 days. So, what’s up with that?


Ben

 

[AuroraGirl]

What I’m getting at is how many days does your q-jet hold fuel so when you go to start it and pump the throttle, it’s actually squirting fuel? My 82 with a Holley will last literally the better part of a month before I have extended cranking to get fuel to the bowl and accelerator pump. My 86 with an edelbrock lasts just more than a week. So far my 76 with a freshly rebuilt, and epoxied well plugs lasts about 3 days. So, what’s up with that?


Ben

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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[AuroraGirl]

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.

 

[wanderinthru]

I would say with todays gas, it has more to do with the temp of the engine when you turn it off. Put an Elderbrock on my 75 a while ago, (The Q jet just blew up, and I had the Elderbrock on the shelf) but, it's setting on the cast iron intake, with no insulator spacer..didn't have that laying around. That thing will be bone dry with in seconds of turning it off, and has to cool down before it will start back. Though, just use it around the yard here, never warms up, it can sit for days and fire before it turns over.

Edit to add. With a Q jet or Elderbrock, having an air gap between the fuel inlet, float plunger, and fuel level in the bowl. It would be scientifically awful hard for the gas to siphon back out of the bowl. Are am I missing something?

 

[Itali83]

I could try a check valve to see if that helps. The new needle and seat is the “window” style so if a little fuel does boil off (which I believe it does) then when the float drops, the rest of the fuel can easily drain back through the opening in the bottom of the seat fitting/insert thingy. Maybe I will try that.

Ben

 

[Itali83]

Here’s the difference between stock and “high flow needle seat”. Stock fuel would have to defy gravity and jump up to flow back out the needle. New style can run out the side window area. That’s what came in my kit, I didn’t order it specifically for more power or anything. This may be the culprit.

Ben

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[Itali83]

I would say with todays gas, it has more to do with the temp of the engine when you turn it off. Put an Elderbrock on my 75 a while ago, (The Q jet just blew up, and I had the Elderbrock on the shelf) but, it's setting on the cast iron intake, with no insulator spacer..didn't have that laying around. That thing will be bone dry with in seconds of turning it off, and has to cool down before it will start back. Though, just use it around the yard here, never warms up, it can sit for days and fire before it turns over.

Edit to add. With a Q jet or Elderbrock, having an air gap between the fuel inlet, float plunger, and fuel level in the bowl. It would be scientifically awful hard for the gas to siphon back out of the bowl. Are am I missing something?

I thought the same exact thing about flow back but then I pictured the new style needle seat and am thinking it could actually be a possibility.

Ben

 

[wanderinthru]

I thought the same exact thing about flow back but then I pictured the new style needle seat and am thinking it could actually be a possibility.

Ben

By no means am I saying it don't happen, I just can't see how. Using an Oklahoma credit card, aka siphon there can be no interuption. So the air above the float would cancel the siphon, with the fuel leaving the top of the bowl. Plus the head pressure, where the fuel would be re entering the fuel tank at the bottom??

If you remember life before ethenol, this didn't happen.

Did not see your new needle/plunger. Not sure what I'm seeing as I look at it. If the seat is down in the bowl, below the fuel level. Then yes the fuel could flow back to the tank.

 

[SquareRoot]

EFI. Nullifies these theoretical conversations.

 

[AuroraGirl]

EFI. Nullifies these theoretical conversations. [/QUOTEefi fuel pumps can be weak and leak back and lose their prime.
Check mate, lib

 

[AuroraGirl]

I’d like to see EFI fix this:

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[wanderinthru]

I’d like to see EFI fix this:

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That will require a LS swap, or at least a big block????

 

[AuroraGirl]

That will require a LS swap, or at least a big block????

At least a big block

 

[wanderinthru]

EFI. Nullifies these theoretical conversations.

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.

 

[idahovette]

My engine in my K20 is sick(V7) so I don't run it very often. I have to crank and pump for quite awhile before it fires...and smokes. I just use it as my workout for that particular day. Never fails to start, just tests the battery and the starter. Not really concerned