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Old 06-28-2004, 07:51 PM
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Any Q-jet experts?

My recently rebuilt q-jet spills fuel from the throttle plate staft after the engine is shut off and occasionally floods out when driving. It's on a '76 K5 Blazer. I rebuilt it myself and everything seemed to be pretty simple. I matched the gaskets, changed the needle and seat, accelerator pump diaphram, float. The truck runs a lot better than it did before the rebuild. Some of the passages were clogged with gunk and the pump diaphram was hardened and severly cracked. The first time the flooding happened I opened the carb back up and found that the little clip that attaches the float to the needle had come off and was just dangeling so I took it off completely since there was not one on it before I did the rubuild. That was not the problem. It's still flooding and when I was doing some rerouting of some wires today I noticed that when I shut the engine off fuel started to spiew out from the throttle plate shaft, mainly on the primary passanger side and on the secondary driver side.

Does anybody have any ideas?

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Old 06-28-2004, 08:04 PM
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Check the float height, also check the fuel pressure, when you shut it down make sure it`s not holding pressure, if it is holding pressure after shut down, check over the vent lines. also check the needle and seat assembly for trash, make sure the rubber tip is still on the tip of the needle.
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Old 06-28-2004, 08:15 PM
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The throttle plate shafts probably needs new bushings. You can buy a kit for this.
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Old 06-28-2004, 08:44 PM
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Worn throttle shaft will not cause flooding.

The little clip needs to be put on the needle right, and check the float and see if it is saturated.

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Old 06-28-2004, 08:47 PM
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Q-jets are usually pretty simple to fix but as mentioned, new throttleshaft bushings are often needed. The throttle shaft bushings were bad because all the forces are in the same direction. You can sometimes eliminate yours wearing prematurely by moving the return springs to pull foreward instead of pulling on the shaft rearward the same as the throttle cable.. I would also put the clip back on the float.
I have seen similiar problems before that were caused by fuel, in the steel line between the pump and carb, perculating due to heat soak after the engine shuts off.
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Old 06-28-2004, 09:07 PM
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Had the same problem, bought a 4.5psi holley regulator and the problem went away.

Then I had to tear the engine apart cause it failed a compression check (not related)
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Old 06-28-2004, 09:18 PM
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Yeah I forgot to mention that I cured mine with a fuel pressure regulator too. It was on a Ford 300 and I had it down to about 1.5 psi before it started starving a little on hard pull, put it back to 1.7 and it was happy and the problem solved.
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Old 06-28-2004, 10:23 PM
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Flood

Doc here


Get a Bush kit, And Replace it . Check the Float Level. Did you Dunk the Carb in cleaner , or just install new parts?

On the Very Bottom of the Main Bowls above the throttle plate There are Two Cast Dimples That are Filled With epoxy are these leaking or the one on the right side? If so clean ane reapply new epoxy.

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Old 06-28-2004, 10:44 PM
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Re: Flood

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Originally posted by docvette
Doc here

On the Very Bottom of the Main Bowls above the throttle plate There are Two Cast Dimples That are Filled With epoxy are these leaking or the one on the right side? If so clean ane reapply new epoxy.

Doc

Doc, are you refering to what I would describe as soft plugs? I thought they looked like they were made from lead. I thought those areas were dead sections in the carb. I forgot to put them in upon initial reassimbly but remembered them before I started the truck. I put them back in their og spots but they are not as tight in their holes. If those bowls are for containing fuel instead of dead space like I assumed, this may be where my problem is.
Every now and then the truck is hard to start like the carb is dry.

I soaked all of the major components in carb cleaner for cleaning then blew everything out. Who likes handeling dirty parts more than once?
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Old 06-28-2004, 11:20 PM
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Soft Plugs

Doc here:

I rebuilt Mine 3 months ago, Mine were Epoxy filled Leaded Soft Plugs (But the Carb was a Reman installed last year, So they might add the epoxy in reman.)

The Plug on the LEFT side of mine was leaking after dipping it, So I had to pull it and epoxy it again, I believe, but am not sure These are part of the circuit going to, or coming from, the Primary pump well bottom, BUT as I said before, I'm not sure of that. I do know in fact these are not Dry, as mine leaked!

So that might be the problem, BTW, Mine was always dry too, took 10 to 15 cranks to get it going on an overnight engine...

Sounds like maybe the same thing.

Amen on the Dirty Parts!

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Old 06-29-2004, 01:01 AM
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Re-epoxying the well plugs has been thouight to be a fix for the dry bowl hard strart for years. It may be true but the problem was thought to be solved later by the addition of the little check valve in the fuel filter. Make sure you do both.
And my take on the soaking cleaner, I absolutly can't stand to be around the stuff anymore and I just use a can of Berryman's B-12 with the little red straw on the nozzle. Spray it through all the passages and clean off the outside too. Then use the air to blow it dry. If your carb is real greasy just use regular parts solvent and a brush to clean it first.
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Old 06-29-2004, 01:11 AM
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Carb Cleaner

[color=lightblue]Doc here

Right on about the Carb Cleaner...Willowbilly! I get Sick for Days around that stuff! Maybe it's our Age... Ya think?

Anyway I did mine EXACTLY the way you outlined and had the same results as with the dip 4 cans of Spray cleaner Vs a Gallon of toxic waste... Gimme The spray Can!

Doc
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Old 06-29-2004, 01:33 AM
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Could be Doc, when I was a kid I used to stick my hand in the bucket. Now I don't even like to get the smell of gasoline on me but nothing is as putrid as carb dip. When I last used it back in the 80s I would scrub the hide off my hands and still wake up in the night from the smell of it on me. I had a friend with a cyl. head shop and he had a barrel of it to dip all the aluminum heads in. I got to where I couldn't go visit his shop because the smell would get in my clothes. He always had all these red blotches and blisters all over his hands and fore arms. After he got out of the business it all cleared up.
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Old 06-29-2004, 03:32 AM
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Carb dip

[color=lightblue]Doc again

Same here, That stuff is so toxic and So Permeating, It's a wonder you can still Buy it...

If I get it on my Skin, It Dies and flakes off for like a week, turns the skin BRIGHT red (This can't be a good sign) And literally Makes Me feel at 8 PM like a review of my lunch is forthcoming...

Whenever anybody asks me about using the stuff, I always Say, Get a BIG bucket, Apron, Gloves and Respirator with eyewear, Find a spot Way Way Way away from the house / Garage Because if you Spill just a few OZ of it on the floor you'll Smell it for months! Dump all your stuff afterwards Including the dip...Cuz You don't want any of it hanging around.

Maybe in OUR younger Days, We Didn't take notice so much, But now adays I don't even run my Car (s) Near the house cuz I hate the Smell of The Exhaust Filling the house... (So do my neighbors , along with the Vibrations from the Flow masters..)

Another one is Engine Degreaser... If I have to, I only do it on Hot Summer Days, So I can leave the windows open over the next 500 miles or so, until it dissipates..


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Old 06-29-2004, 05:43 AM
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There was a GM bulletin in the late sixties about those leaking soft plugs.

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