gas cap leaking

[madmaxx57]

as the title says..my gas cap is cracked..didnt realize it was leaking until we launched at the track...i put on the gas cap from 99 chevy 2500..it still spilled too and about 1/2 track i hear the tank pop..died at about 1000ft..on the return road i took it off and drove back to the pits..the same cap we put a walmart bag (yea i know) over the cap to help seal it (over the threaded part)..no leaks but again off at 1000ft....i noticed the flap on the tank inlet is gone...this is a sumped stock tank one fuel line to the mech. pump...will a regular 78 malibu cap solve this or is it the missing flap causing most of the problem.. 3/4 of a tank of fuel..1.7s 60 ft..thanks

 

[LS6 Tommy]

Sounds like you need to vent the tank. did you cap or plug the charcoal cannister line?

Tommy

 

[madmaxx57]

all that is gone. top of the tank is routed back to itself..i'm thinking a regular vented cap will still leak from the fuel running up filler..my cracked cap is vented..i'm going to get a new vented one tomm to try it i was just wondering if anyone has had this issue before..with the cap sealed it obviously sucks the tank down..this is a street/strip ride with all excess baggage removed..lol..car runs fine with the cracked cap it just leaks..which the track officials kinda frown on..lol

 

[LS6 Tommy]

You need to use the factory vapor line port to vent. Adding a vent to the stock gas cap will almost always leak.

Tommy

 

[melloelky]

You need to use the factory vapor line port to vent. Adding a vent to the stock gas cap will almost always leak.

Tommy

so if all that oe stuff is gone,whats the fix for this?one of the lines coming outta top of the sender can be used to vent the tank?or will that emit fumes having an open line?didn't phillip loop his vent to a small k&n looking filter?hmmmmm :-k

 

[LS6 Tommy]

My fix for race cars is a small breather filter & a check valve on the stock vapor return line port on the tank so it never gets into a negative pressure condition & you don't vent fuel vapor out. That's more or less how the old vented caps worked. If you wanna be sneaky & look stock, you can probably mod the charcoal cannister to do the same thing. That's probably what I'll do.

Tommy

 

[melloelky]

My fix for race cars is a small breather filter & a check valve on the stock vapor return line port on the tank so it never gets into a negative pressure condition & you don't vent fuel vapor out. That's more or less how the old vented caps worked. If you wanna be sneaky & look stock, you can probably mod the charcoal cannister to do the same thing. That's probably what I'll do.

Tommy

a check valve and a filter?hmmm are these check valves anything special?

 

[grizwald]

i used one of the little plastic vents that are used on diff housings pushed into a short piece of rubber hose, hooked to the sender. no problems so far.

 

[melloelky]

i used one of the little plastic vents that are used on diff housings pushed into a short piece of rubber hose, hooked to the sender. no problems so far.

yea :-k

 

[grizwald]

something like this one.....

http://www.summitracing.com/parts/RNB-14689/?rtype=10