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Author Topic: Sudden gas overflow problem  (Read 2600 times)

Offline tommyboombotz

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Sudden gas overflow problem
« on: April 03, 2019, 05:32:21 AM »
Good Morning Everyone! Ive got an 87 R10 long bed with dual tanks, and the truck runs fine. Lately I've been noticing that the passenger side gas tank has been leaking gas from the filler. I will drive around town for a bit, then when i get home, I notice there is a uncomfortable amount of gas leaking from the filler. When I open the gas cap, (Its has a push button to vent gas prior to opening if thats any help), gas starts to just pour out. I know theres maybe only 4 or 5 gallons of gas in that passenger tank, but the gas is all the way to to the top of the filler. Now this doesn't happen on the driver side, only the passenger side. Any ideas whats going on? Truck runs just fine otherwise.

Thanks in advance,
Tom
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Offline Captain Swampy

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Re: Sudden gas overflow problem
« Reply #1 on: April 03, 2019, 06:32:57 AM »
The switching valve probably needs replacing.
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Offline Irish_Alley

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Re: Sudden gas overflow problem
« Reply #2 on: April 03, 2019, 01:29:48 PM »
i know ford had an issue where the valve would pull from one tank but the return would go to the other side. it would overfill the tank and flood the engine causing it to run real poor. but ive never heard of a chevy do it. my question is if you do switch tanks does it still do this? and is the tank full now even though you think theres only 4 or so gallons?
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Offline VileZambonie

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Re: Sudden gas overflow problem
« Reply #3 on: April 03, 2019, 04:20:59 PM »
You probably have the lines plumbed in incorrectly. 1/4" Teed vent, 5/16 return, 3/8" feed. Check the canister hose routing as well. Refer to the diagrams in the technical forum.
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Offline bedwards

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Re: Sudden gas overflow problem
« Reply #4 on: April 03, 2019, 07:43:05 PM »
I just went through this with a 85' with dual tanks. The valve was either not switching all the way or leaking inside. The truck literally pumped gas from the driver side to the passenger side and ran it over to the tune of 2-3 gallons. As if this weren't dangerous enough, it also filled up the vent lines to the canister until it was flooding the carb.
It gave me a pretty good scare when all that fuel kept flowing from the passenger tank.
A new valve cured the problem. I have driven it to work for the last two days and it is back to normal.
here is the post:
http://forum.73-87chevytrucks.com/smforum/index.php?topic=37300.0

good luck
« Last Edit: April 03, 2019, 07:51:10 PM by bedwards »
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Offline tommyboombotz

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Re: Sudden gas overflow problem
« Reply #5 on: April 04, 2019, 05:52:41 AM »
Quote from: VileZambonie on April 03, 2019, 04:20:59 PM
You probably have the lines plumbed in incorrectly. 1/4" Teed vent, 5/16 return, 3/8" feed. Check the canister hose routing as well. Refer to the diagrams in the technical forum.

I thought that too, but its correct, its been running fine for months, this just started happening maybe a few days ago.
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Offline tommyboombotz

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Re: Sudden gas overflow problem
« Reply #6 on: April 04, 2019, 05:56:27 AM »
Quote from: bedwards on April 03, 2019, 07:43:05 PM
I just went through this with a 85' with dual tanks. The valve was either not switching all the way or leaking inside. The truck literally pumped gas from the driver side to the passenger side and ran it over to the tune of 2-3 gallons. As if this weren't dangerous enough, it also filled up the vent lines to the canister until it was flooding the carb.
It gave me a pretty good scare when all that fuel kept flowing from the passenger tank.
A new valve cured the problem. I have driven it to work for the last two days and it is back to normal.
here is the post:
http://forum.73-87chevytrucks.com/smforum/index.php?topic=37300.0

good luck

I honestly havent tried switching to the passenger side tank. I'll give it a go this afternoon.

Either way, Im just going to buy a new valve today and see if that fixes the problem.

Thanks,
Botz
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Offline tommyboombotz

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Re: Sudden gas overflow problem
« Reply #7 on: April 08, 2019, 05:10:13 AM »
Turns out it was the valve! I ordered a brand new AC Delco one from the Rock. I switched from the driver side tank to the passenger tank, drove it all weekend, and no leaking issues. As soon as the new one comes i'll throw it in. Thank you everyone for the input.

Botz
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