Installed new gas tank fills slow! Why?


Old 04-09-10, 08:26 AM
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Join Date: Nov 2008
Location: mid-ohio
Posts: 40
Question Installed new gas tank fills slow! Why?

Hi All,
I just installed a brand new gas tank in my 1985 Pontiac Parisienne. I had a leak about half way up on the old one. The problem I am having is when I put gas in I can hear it filling up the tube and then BOOSH it blows out around the pump nozzle ! Well I tried it again with the same result BOOSH all over the ground . By the time I tried it the third time the lady at the station was getting pissed because she had to come out and spread the oil dry :Take One:. Well I finally filled it by just barely squeezing the handle, keep in mind this is a 24 gallon tank, and this big boat can drink gas faster than I was able to fill it :NWhining:.
OK here are the facts: Brand new tank with filltube already welded on, brand new sender gaskit and nut, brand new rubber fuel and vent lines. Removal and installation went very well . So what the heck is going on .
In typing this I got an Idea! Perhaps the vent tube is plugged somewhere and the old tank was venting through the rust hole during filling. Sooo when we replaced the tank we also plugged the "vent" (rust hole). What do you think? If you think can you give me a good starting point for finding the plug in the return or vent line? As always you guys are great and I appreciate and applaud any ideas you are willing to share!
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Old 04-09-10, 09:16 AM
mickblock's Avatar
Join Date: Feb 2009
Location: Calumet Township, Indiana
Posts: 616
Is is at all possible that the saftety shutoff or regulator was out of order on the nozzle you used?

A properly working fuel nozzle should have just snapped shut. NOT go BOOSH.

You say that you can hear the fillerneck fill up before spilling over.

Other than that I'm just thinking kink or blockage.
Was this new part ever shipped?

Can you describe the sound again? lol!
Old 04-09-10, 09:48 AM
Join Date: Mar 2009
Location: Texas
Posts: 1,051
If the new tank is exactly formed and shaped the same as the old one, including the fuel inlet tube, (it may not be) and there are no kinks in the inlet hose it sounds like a venting problem could be causing this. Have you tried to disconnect the Evap canister temporarly to see if there is any difference for example. That system and device if original is getting well up there in age.

Several years ago, poor tank design caused fuel kick back on some cars so that is why I am wondering about your new after market tank if nothing else obvious can be found. It could be this simple.
Old 04-09-10, 10:22 AM
Join Date: Oct 2008
Posts: 1,312
This is a problem with the EVAP system. Look for kinks in hoses.

Also probably unrelated to your problem, but worth mentioning, repeated "topping off" of the gas tank can cause the charcoal canister of the EVAP system to fill with gas. Then you also have this filling problem. Could it be the old tank was venting out the leak?

Anyway as fuel pours into the tank, air needs to be able to flow out the EVAP system.

Note there are probably solenoid valves on the EVAP system and it can be somewhat complex. If all else fails, you can order a factory service manual set of books from or your dealer and this would have complete detailed troubleshooting instructions for this problem.
Old 04-17-10, 08:31 AM
Thread Starter
Join Date: Nov 2008
Location: mid-ohio
Posts: 40
Thanks for your suggestions. The pump nozzle did shut off, too late to stop the surge of gas.
I pulled the vent line off the evap canister, took the cap off the tank, and tried to blow through. No luck. Hooked a small compressor to the line to try and blow out a "plug". It took 20 psi before I heard air moving into tank. Disconnected compressor and tried to blow again still no luck. I hate to have to replace the whole metal line but I can see no other option. Do you have any more suggestions?
Old 04-17-10, 08:39 AM
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Location: Calumet Township, Indiana
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When you put gas into the tank to get to the gas station how did that go?
Old 04-17-10, 05:26 PM
Join Date: Feb 2005
Location: USA
Posts: 1,396
Like this...BOOSH!
Sorry, couldn't resist.
Old 04-19-10, 12:01 PM
Thread Starter
Join Date: Nov 2008
Location: mid-ohio
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My son only put in a couple of gallons. He was using a funnel so the tank could have been venting through the fill tube. Slow rate of fill in a large fill pipe. No indication of BOOSH in my future.
The problem is definately a blocked vent line. The question we have now is; should we try to clear it (run a wire down through) or just throw in the towel and replace?
Old 04-19-10, 04:33 PM
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Compressed air won't do the trick? that would get around bends more easily than a wire.

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