HELP!!!! before I shoot the truck - The 1947 - Present Chevrolet & GMC Truck Message Board Network

fast71 · 10-10-2004, 09:09 PM

I was having problems with trash in my carb ,rust,so I changed the fuel tank.
I got one out of a 68 model. now my truck is a 71 so we know there is a difference in tanks.Well here is my problem , this tank is building pressure cuasing the rear float on my Holley to hang. Now i know the first thing is a vented Cap ,I have done that. I have gone as far as to make sure the cap wasnt stopped up by blowing air thru the the vent.It is still building pressure.Help Please.

chickenwing · 10-10-2004, 09:34 PM

Could you go to a vented sending unit and run the vent line parallel to the fuel line out of the cab?

Tx Firefighter · 10-10-2004, 10:00 PM

If you're getting pressure, the cap isn't venting. I don't care if you tested it or not, it's obviously not venting.

A new cap is 5 bucks at any parts store.

Don't get the universal one, they look like crap. Tell the parts guy at the counter that you want a Stant brand one. They come in a box off the shelf behind the counter.

They look like the original one too.

fast71 · 10-10-2004, 10:17 PM

I should have also mentioned . I work at Advance Auto parts and I'm on my 2nd cap. thats the reason I mentioned that I have even tested the caps. I have 2 now if anyone needs an extra

.
Thanks for the answer but that is not working. Oh it was a stant #11623.I looked to see if there was a different part # and it listed another but it was for over 7500gvw and it didnt look the same as what goes on my tank. I'm soory I forgot to mention that i have tried that .

Tx Firefighter · 10-10-2004, 10:26 PM

Look at it this way, the cap vents to keep the tank from building up pressure. For some reason, your cap isn't venting. I mean, it has to be right?

Try driving it without the cap to see if the problem goes away.

fast71 · 10-10-2004, 10:28 PM

could it be the vent spring is to tight.or stiff to let the pressure go.

Tx Firefighter · 10-10-2004, 10:35 PM

So, does the catalog list different caps for 68 and 71 trucks?

The 71 used a closed sytem as I remeber with a charcoal canister. The 71 cap shouldn't be vented. It's purpose was to contain all the vapors of the fuel to keep them from getting into the environment. The 71 tank should have the vent line deal that ran up into the cab corner didn't it? A big loop.....

The 68 tank didn't use the cansiter, the cap should be vented.

10-10-2004, 09:34 PM	#2
chickenwing Lovin' Life in Miss.! Join Date: Mar 2004 Location: Puckett, Mississippi Posts: 1,937	Could you go to a vented sending unit and run the vent line parallel to the fuel line out of the cab? __________________ The truck... you hear that? No really, you did hear that?!!!

10-10-2004, 10:00 PM	#3
Tx Firefighter Watch out for your cornhole ! Join Date: Jun 2003 Location: Azle, Texas Posts: 14,162	If you're getting pressure, the cap isn't venting. I don't care if you tested it or not, it's obviously not venting. A new cap is 5 bucks at any parts store. Don't get the universal one, they look like crap. Tell the parts guy at the counter that you want a Stant brand one. They come in a box off the shelf behind the counter. They look like the original one too. __________________ I'm on the Instagram- @Gearhead_Kevin

10-10-2004, 10:17 PM	#4
fast71 Drive it like U stole it Join Date: Mar 2000 Location: tunnel hill ,GA /Chatt,TN Posts: 956	I should have also mentioned . I work at Advance Auto parts and I'm on my 2nd cap. thats the reason I mentioned that I have even tested the caps. I have 2 now if anyone needs an extra . Thanks for the answer but that is not working. Oh it was a stant #11623.I looked to see if there was a different part # and it listed another but it was for over 7500gvw and it didnt look the same as what goes on my tank. I'm soory I forgot to mention that i have tried that . __________________ 71 custom 10 swb 72 nova ss 72 nova custom 87 s10 96 burb 94 camry 53 5 window 3100

10-10-2004, 10:28 PM	#6
fast71 Drive it like U stole it Join Date: Mar 2000 Location: tunnel hill ,GA /Chatt,TN Posts: 956	could it be the vent spring is to tight.or stiff to let the pressure go. __________________ 71 custom 10 swb 72 nova ss 72 nova custom 87 s10 96 burb 94 camry 53 5 window 3100

10-10-2004, 10:35 PM	#7
Tx Firefighter Watch out for your cornhole ! Join Date: Jun 2003 Location: Azle, Texas Posts: 14,162	So, does the catalog list different caps for 68 and 71 trucks? The 71 used a closed sytem as I remeber with a charcoal canister. The 71 cap shouldn't be vented. It's purpose was to contain all the vapors of the fuel to keep them from getting into the environment. The 71 tank should have the vent line deal that ran up into the cab corner didn't it? A big loop..... The 68 tank didn't use the cansiter, the cap should be vented. __________________ I'm on the Instagram- @Gearhead_Kevin

10-10-2004, 09:09 PM	#1
fast71 Drive it like U stole it Join Date: Mar 2000 Location: tunnel hill ,GA /Chatt,TN Posts: 956	HELP!!!! before I shoot the truck I was having problems with trash in my carb ,rust,so I changed the fuel tank. I got one out of a 68 model. now my truck is a 71 so we know there is a difference in tanks.Well here is my problem , this tank is building pressure cuasing the rear float on my Holley to hang. Now i know the first thing is a vented Cap ,I have done that. I have gone as far as to make sure the cap wasnt stopped up by blowing air thru the the vent.It is still building pressure.Help Please. __________________ 71 custom 10 swb 72 nova ss 72 nova custom 87 s10 96 burb 94 camry 53 5 window 3100

10-10-2004, 10:26 PM	#5
Tx Firefighter Watch out for your cornhole ! Join Date: Jun 2003 Location: Azle, Texas Posts: 14,162	Look at it this way, the cap vents to keep the tank from building up pressure. For some reason, your cap isn't venting. I mean, it has to be right? Try driving it without the cap to see if the problem goes away.



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