Missing Gas Mystery
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Freshman User
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Missing Gas Mystery
Subject: 1980 F100 300 I-6. Problem: park it overnight and it's crank, crank, crank...until the fuel bowl refills. It doesn't do it in cold weather. Now that the weather is warmer, it's back to the old cycle. I've had this carb apart many times and can see no way for gravity drain. It must be boiling the gas out???? Had the same problem last summer. Replaced fuel pump....no change.
A friend says that it's being syphoned out and it's a vent problem. I'm inclined to think this may be the case. As it seems that the problem doesn't appear...unless the truck sits overnight... Just call me perplexed.
A friend says that it's being syphoned out and it's a vent problem. I'm inclined to think this may be the case. As it seems that the problem doesn't appear...unless the truck sits overnight... Just call me perplexed.
Elder User
Joined: Nov 1999
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Missing Gas Mystery
Could indeed be siphoning. My 80 does the same thing. It's been that way ever since someone changed from dual tanks to single in order to put the current body on. There are hose down there I don't want to mess with, but I installed a see-through filter and as soon as the engine is shut off, the gasoline disappears.
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Joined: Jan 2001
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From: Nebraska
Missing Gas Mystery
[font size="1" color="#FF0000"]LAST EDITED ON 15-May-01 AT 07:52 PM (EST)[/font][p]Does it start right up if you pump the gas pedal a few times first? Mine has been this way ever since a new carb last year but starts fine after I pump it a few times.
1986 F-150 4x4 300 I6 NP435
1986 F-150 4x4 300 I6 NP435
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Freshman User
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Missing Gas Mystery
>Does it start right up if
>you pump the gas pedal
>a few times first?
No. Yah gotta crank, crank, crank. It's like the fuel bowl is totally empty. Just like you ran outta gas and then try to start it. I'd say it takes 20 seconds of cranking to get it started. During cold weather, just push the gas pedal enough to let choke reset and it starts right up. I'm going to leave the gas cap off tonight and see if anything changes.
>you pump the gas pedal
>a few times first?
No. Yah gotta crank, crank, crank. It's like the fuel bowl is totally empty. Just like you ran outta gas and then try to start it. I'd say it takes 20 seconds of cranking to get it started. During cold weather, just push the gas pedal enough to let choke reset and it starts right up. I'm going to leave the gas cap off tonight and see if anything changes.
Senior User
Joined: Mar 2001
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Missing Gas Mystery
Two possibilities.
1) Accelerator pump needs replacing on the carb. If that's not it, then
2) Replace the mechanical fuel pump with an electric one. With this fix you would turn the key on and wait for the bowl to fill. Shouldn't take more than a few seconds.
1) Accelerator pump needs replacing on the carb. If that's not it, then
2) Replace the mechanical fuel pump with an electric one. With this fix you would turn the key on and wait for the bowl to fill. Shouldn't take more than a few seconds.
