Fuel coming out of my vent tube

[DarrinWI]

For the 5.3 swap in my El Camino I bought the 4.3 tbi fuel tank and the tbi sender from Dixie Restorations. I have an issue where gas pours out of my vent tube. I’m using the 3/8” line for supply, the 5/16” line for the return and the 1/4” for the vent. The car sat for a day or two and vented about 5 gallons of gas.

I dropped the tank today looking for a fuel starvation issue (ended up being having no gas in the tank) and put everything back together. I added about 10 gallons of gas and on the test drive I smelled fuel when stopped at a light. When I pulled into my driveway I can see the trail down the street.

Any insight into the issue? TIA

 

[1320chevy]

For the 5.3 swap in my El Camino I bought the 4.3 tbi fuel tank and the tbi sender from Dixie Restorations. I have an issue where gas pours out of my vent tube. I’m using the 3/8” line for supply, the 5/16” line for the return and the 1/4” for the vent. The car sat for a day or two and vented about 5 gallons of gas.

I dropped the tank today looking for a fuel starvation issue (ended up being having no gas in the tank) and put everything back together. I added about 10 gallons of gas and on the test drive I smelled fuel when stopped at a light. When I pulled into my driveway I can see the trail down the street.

Any insight into the issue? TIA

No answer, but, is the tank under pressure while the engine is running? (remove the gas cap... does it "woosh" ?

 

[DarrinWI]

No answer, but, is the tank under pressure while the engine is running? (remove the gas cap... does it "woosh" ?

It did the day that it spit all the fuel out. I don’t have the cap on tight currently.

 

[ELCAM]

The 1/4 inch is the return and goes half way down. If it is covered with gas and is used as the vent will build pressure and flow gas out the vent anytime the tank is over about 1/2 full.

5/16 is the shortest tube into the tank.

Change to 1/4 as the return and 5/16 as vent.

 

[DarrinWI]

The 1/4 inch is the return and goes half way down. If it is covered with gas and is used as the vent will build pressure and flow gas out the vent anytime the tank is over about 1/2 full.

5/16 is the shortest tube into the tank.

Change to 1/4 as the return and 5/16 as vent.

Thank you. I should have paid attention to the tube lengths inside the tank.

 

[Built6spdMCSS]

Let me show you how to fix that..
See the slit with the red circle around it?

 

[Built6spdMCSS]

The 1/4 inch is the return and goes half way down. If it is covered with gas and is used as the vent will build pressure and flow gas out the vent anytime the tank is over about 1/2 full.

5/16 is the shortest tube into the tank.

Change to 1/4 as the return and 5/16 as vent.

Negative.

My picture above it the proper fix. 1/4" return with these newer engines is not enough. Drill out the restriction on the 5/16" and it works fine. It's drilled out in my pic, been working since 2010 with no issues.

Here is that little restriction before I drilled it with the baffle cut off.

 

[DarrinWI]

Negative.

My picture above it the proper fix. 1/4" return with these newer engines is not enough. Drill out the restriction on the 5/16" and it works fine. It's drilled out in my pic, been working since 2010 with no issues.

Here is that little restriction before I drilled it with the baffle cut off.

View attachment 224075

Thanks for the tip. So I’m clear, the restrictor is in the 5/16 tube which is the factory vent, but I’m using as the return. Drilling this out should stop the fuel from coming out of my 1/4” line?

 

[Built6spdMCSS]

Thanks for the tip. So I’m clear, the restrictor is in the 5/16 tube which is the factory vent, but I’m using as the return. Drilling this out should stop the fuel from coming out of my 1/4” line?

Do you still have that restrictor in place? If so the return is barely working. Fuel pressure is spiking I bet, hope you have a regulator.

Putting a slit or drilling a hole in the 1/4" tube very close to the top like I did will help it vent, look close at them pics and think about how it works then you will see why I did what I did.

 

[DarrinWI]

Do you still have that restrictor in place? If so the return is barely working. Fuel pressure is spiking I bet, hope you have a regulator.

Putting a slot or drilling a hole in the 1/4" tube very close to the top like I did will help it vent, look close at them pics and think about how it works then you will see why I did what I did.

I was going back and forth between your pics and ones I took today. It makes sense now. Yes, that restrictor is in place. I have a regulator but was going to chase down a cause of high fuel pressure. I think I’ve found it now. Thank you for sharing your knowledge and experience.