loosing prime in carb
May 14th, 2012, 05:21 PM
#1
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loosing prime in carb
i have a 73 hurst olds and my quadrajet is loosing prime. carb has been rebuilt and plugs have been epoxied new fuel pump and have check all gas lines for leaks NONE!
any help would be appreciated.
Thanks
Keith
any help would be appreciated.
Thanks
Keith
May 14th, 2012, 06:42 PM
#2
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Posts: 116
have you tried adjusting your choke? My quadrajet was taking 30 pumps and a lot of turning over to start,I adjusted the choke, turning counterclockwise towards the rear of motor and now it starts normal. I am assuming you have a electric choke.
May 15th, 2012, 05:44 PM
#4
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The fuel filter is located in the carb, correct. I will pull it and check it.
I had it professionally rebuilt? I will pull the filter. They could have put one in without a check valve. Any one have a picture of what one would look like?
thanks
K
I had it professionally rebuilt? I will pull the filter. They could have put one in without a check valve. Any one have a picture of what one would look like?
thanks
K
May 15th, 2012, 07:22 PM
#5
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Are you uncertain?
No check valve = plain metal filter end with a hole in the middle.
Check valve = metal filter end with a hole in the middle that has a grey rubber plug in it.
Ya can't miss it.
- Eric
No check valve = plain metal filter end with a hole in the middle.
Check valve = metal filter end with a hole in the middle that has a grey rubber plug in it.
Ya can't miss it.
- Eric
May 17th, 2012, 03:28 AM
#8
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Is it actually empty? That is, have you actually seen that there is no fuel in it at all?
If so, how long does it take for it to become empty?
Completely empty would be very unusual, as the fuel would have to either entirely evaporate up through the vent tube, or completely leak out through a hole or other leak in the casting (and plugs are not generally leaky in '73 carbs, and you say yours were epoxied for good measure, so there would have to be an actual hole somewhere).
- Eric
If so, how long does it take for it to become empty?
Completely empty would be very unusual, as the fuel would have to either entirely evaporate up through the vent tube, or completely leak out through a hole or other leak in the casting (and plugs are not generally leaky in '73 carbs, and you say yours were epoxied for good measure, so there would have to be an actual hole somewhere).
- Eric
May 17th, 2012, 08:26 AM
#9
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Location: ID
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I have this problem, and I'm convinced that it is evaporation. QJets have a small fuel bowl, so it doesn't take long to disappear. I've set the carb on cardboard, and filled up the bowl. Came back a few days or week later and it was empty, and NO sign of seepage on the cardboard. Thinking of electric fuel pump.
May 17th, 2012, 04:16 PM
#10
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Is it actually empty? That is, have you actually seen that there is no fuel in it at all?
If so, how long does it take for it to become empty?
Completely empty would be very unusual, as the fuel would have to either entirely evaporate up through the vent tube, or completely leak out through a hole or other leak in the casting (and plugs are not generally leaky in '73 carbs, and you say yours were epoxied for good measure, so there would have to be an actual hole somewhere).
- Eric
If so, how long does it take for it to become empty?
Completely empty would be very unusual, as the fuel would have to either entirely evaporate up through the vent tube, or completely leak out through a hole or other leak in the casting (and plugs are not generally leaky in '73 carbs, and you say yours were epoxied for good measure, so there would have to be an actual hole somewhere).
- Eric
May 17th, 2012, 06:35 PM
#11
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Hmmmmm...
Ida know. 3-4 days seems like an awful short time for full to completely empty.
If you'd said 2 weeks I'd have said that was within normal limits.
I wonder whether it would be worth the trouble to fashion a small plug to fit in the vent tube to reduce evaporation.
Have you checked for leaks by removing your carb and filling it with something very volatile, like acetone, and seeing if the bottom gets wet?
- Eric
Ida know. 3-4 days seems like an awful short time for full to completely empty.
If you'd said 2 weeks I'd have said that was within normal limits.
I wonder whether it would be worth the trouble to fashion a small plug to fit in the vent tube to reduce evaporation.
Have you checked for leaks by removing your carb and filling it with something very volatile, like acetone, and seeing if the bottom gets wet?
- Eric
May 18th, 2012, 10:18 AM
#12
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does the car smell of gas strongly after you run it, shut it down, and let it sit for a half hour? alcohol is what i use to check for leaks overnight. i'm leaning towards percolation here. how is your fuel pump pressure and volume? sometimes, those rubber check valves in the filters stick closed, i've seen that often enough that i quit using them.
bill
bill
May 18th, 2012, 10:41 AM
#13
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I'm a changed man now, though.
Though I won't guarantee that it will work for this poster, for the price, I'd give it a try.
- Eric
May 18th, 2012, 05:18 PM
#14
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Before I changed my car from needing literally 60 seconds of cranking (or 300 seconds of finding the gas can, opening the hood, removing the air cleaner cover, pouring half a cup of gas down the carb, and then putting it all away) to start after 4 days, to needing 5 seconds of cranking to start after two weeks, by installing one of those check valves, I would have given the same advice.
I'm a changed man now, though.
Though I won't guarantee that it will work for this poster, for the price, I'd give it a try.
- Eric
I'm a changed man now, though.
Though I won't guarantee that it will work for this poster, for the price, I'd give it a try.
- Eric
thanks
k
May 18th, 2012, 05:54 PM
#15
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they're installed at the time of filter manufacturing. go to your local auto parts store and ask for a filter for your application, they'll probably show 2 numbers, 1 of them will likely have the check valve. before you install the filter, manually push the white nylon check valve in to break the bond it's likely formed.
bill
bill
May 18th, 2012, 06:51 PM
#16
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This one ought to do it:
It's a Fram CG3389.
You will notice the black rubber on the bottom edge - that's a check valve. If you don't like the way it works, you can just pull it off and throw it away.
This cross references to:
- Eric
It's a Fram CG3389.
You will notice the black rubber on the bottom edge - that's a check valve. If you don't like the way it works, you can just pull it off and throw it away.
This cross references to:
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May 19th, 2012, 05:37 AM
#20
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No.
This is the "long" filter.
The '69 takes the "short" filter.
I don't know whether they make a short filter with the valve, but you could always buy a long one and pop the valve into a short filter.
Just look at the cards on the rack at the auto parts store and pick out the one that looks right.
- Eric
This is the "long" filter.
The '69 takes the "short" filter.
I don't know whether they make a short filter with the valve, but you could always buy a long one and pop the valve into a short filter.
Just look at the cards on the rack at the auto parts store and pick out the one that looks right.
- Eric
Last edited by MDchanic; May 19th, 2012 at 05:39 AM.
May 19th, 2012, 04:13 PM
#22
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I don't understand how a fuel filter with a check is going to keep gas in the carb, I don't think the gas is jumping up out of the bowl back through the needle and seat, there is already (per-say) 2 check valves in the fuel pump which should be stopping fuel movement when shut down.
This really sounds like a peculation problem from heat sinking to me. I'd block the heat to the manifold, use a low temp thermostat, and add an insulator of some sort under the carb and use gas that has no alcohol in it if possible. This is what I did to my car to get rid of this problem and it worked, you can leave it sit for 2 weeks and it starts with one pump of the peddle, it starts no matter if it's cold or hot.
I'd almost bet money it's a combination of heat and cheap gas that's causing this problem. IMHO!
This really sounds like a peculation problem from heat sinking to me. I'd block the heat to the manifold, use a low temp thermostat, and add an insulator of some sort under the carb and use gas that has no alcohol in it if possible. This is what I did to my car to get rid of this problem and it worked, you can leave it sit for 2 weeks and it starts with one pump of the peddle, it starts no matter if it's cold or hot.
I'd almost bet money it's a combination of heat and cheap gas that's causing this problem. IMHO!
May 19th, 2012, 06:07 PM
#24
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I agree, I know of no reason why it should work, but it seems to have worked, so I'm just passing that piece of information along to the rest of you.
For four bucks, it seems to me to be worth a try.
- Eric
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