[Goohead]

hey gang, hoping someone can give me a hand, dropped in a zl1 in take pump, install was easy, but seem to have an issue now where the tank wont take gas, I think it has to do with the vent or fill valve or evap system.

took out pump a 2nd time to make sure my leveler was all set and it was and I wasn't filling up to passed full by accident.

Check to make sure the lines are not kinked and they are all find. From what I am reading it might be this line on coming out of the pump that is responsible for tell the pump when to stop filling. But I thought this was an Evap related line?

When I disconnect it fuel is releases, is this normal? or did I drop this line in fuel inside of the tank and now it is causing the issue. or is it related the 2nd crossover pump? not sure what is going on here, any help is appreciated

please see pic below which I borrowed from another post. The line with fuel in it is highlighted below (evap line?) and where the connector is to the underside of the fuel tank top and associated hose inside the tank itself w orange connector

[ctrlz]

I suspect that fitting where evap/vent connects to the fuel pump has an anti-rollover valve, which prevents a fuel leak in a rollover. It either got stuck or broken.
That green fitting could contain a ball check valve.
Just a guess for now.
I will check the repair manual.

EDIT: see fuel limit vent valve below

DESCRIPTION AND OPERATION > EVAPORATIVE EMISSION CONTROL SYSTEM
DESCRIPTION > EVAP SYSTEM COMPONENTS

The EVAP system consists of the following components:

EVAP Purge Solenoid Valve

The EVAP purge solenoid valve controls the flow of vapors from the EVAP system to the intake manifold.
The purge solenoid valve opens when commanded ON by the ECM. This normally closed valve is pulse
width modulated (PWM) by the ECM to precisely control the flow of fuel vapor to the engine. The valve
will also be opened during some portions of the EVAP testing when the engine is running, allowing engine
vacuum to enter the EVAP system.

Purge Tube Check Valve

NOTE:
The presence of this one-way check valve prevents pressure testing the EVAP system for
leaks at the EVAP canister purge tube connector.

Turbocharged vehicles have a check valve in the purge tube between the EVAP purge solenoid valve
and the intake manifold to prevent pressurization of the EVAP system under boost conditions. Some
applications may have this check valve between the EVAP purge solenoid valve and the EVAP canister.

EVAP Canister

The canister is filled with carbon pellets used to absorb and store fuel vapors. Fuel vapor is stored in the
canister until the ECM determines that the vapor can be consumed in the normal combustion process.

Vapor Recirculation Tube

A vapor path between the fuel fill pipe and the vapor tube to the carbon canister is necessary for Vehicle
Onboard Diagnostics to fully diagnose the EVAP system. It also accommodates service diagnostic
procedures by allowing the entire EVAP system to be diagnosed from either end of the system.
The On-Board Refueling Vapor Recovery System is an on-board vehicle system designed to recover
fuel vapors during the vehicle refueling operation. The flow of liquid fuel down the fuel filler pipe provides
a liquid seal which prevents vapor from leaving the fuel filler pipe. An EVAP pipe transports the fuel vapor
to the EVAP canister for use by the engine.

Fuel Tank Pressure Sensor

The fuel tank pressure sensor measures the difference between the pressure or vacuum in the fuel tank
and outside air pressure. Depending on the vehicle, the sensor can be located in the vapor space on top
of the fuel tank, in the vapor tube between the canister and the tank, or on the EVAP canister. A high fuel
tank pressure sensor voltage indicates a low fuel tank pressure or vacuum. A low fuel tank pressure
sensor voltage indicates a high fuel tank pressure.

Fuel Fill Pipe Check Valve

The check valve on the fuel fill pipe is there to prevent spit-back during refueling.

EVAP Vent Solenoid Valve

The EVAP vent solenoid valve controls fresh airflow into the EVAP canister. The valve is normally open.
The canister vent solenoid valve is closed only during EVAP system tests performed by the ECM like
large leak and engine off natural vacuum test.

Fuel Fill Cap

The fuel fill cap is equipped with a seal and a vacuum relief valve and is tethered. A torque-limiting
device prevents the cap from being over tightened. To install the cap, turn the cap clockwise until you
hear clicks. This indicates that the cap is correctly torqued and fully seated. A built-in device indicates
that the fuel filler cap is fully seated. A fuel filler cap that is not fully seated may cause a malfunction in
the emission system.

Capless Fuel Fill

Some vehicles may have a capless fuel fill design behind a locking fuel door. There is no fuel fill cap to
remove. One just fully inserts the fuel nozzle into the fill neck, making sure it latches before refueling.
Flapper valves close to seal this interface once the fill nozzle is removed.

Fill Limit Vent Valve

This acts as a shut off valve during refueling. This will vary based on fuel tank design. The fuel limit vent
valve has the following functions:
The fuel limit vent valve is located on the inside top of the fuel tank
This valve is not serviced separately
Controls the fuel tank fill level by closing the primary vent from the fuel tank and forcing the fuel fill
nozzle to shut off.
Prevents liquid fuel from exiting the fuel tank via the EVAP pipe to the canister.
Provides fuel-spillage protection in the event of a vehicle rollover by closing the vapor path from

the tank to the EVAP canister.

[Goohead]

Thanks man if you have anything on the repair manual that can help please let me know. I took off that line off as a whole and there was no issues with the line itself or any kind of check value in the line, underneath the pump the line with the orange fitting I can’t tell if it should or should not have touched fuel, but I do remember dropping it in the fuel tank by accident and having to pull it back out

[ctrlz]

Here's a picture of one of these. Not sure what exactly it looks like on the Camaro.
https://www.eaton.com/us/en-us/catal...ent-valve.html

[Goohead]

so on this tank, that valve is I think in the tank. the brown/black plug goes to the bottom of the fuel pump, goes to a line that follows to the filler neck, and inside the tank goes to some kind of valve and stops, there is another line that goes from that "valve" to another value on the opposite side of the tank and is on the top of the tank, I think that is the problem, when I take off this line, there is fuel in it but I am sure there is suppose to be fuel there...

(there are 2 additional lines that also hold fuel and goes from 1 side to another on the tanks)

[ctrlz]

I think your problem is most likely in the fill vent valve. The second place is the evap solenoid. I saw accounts in other forums where people managed to overfill their fuel tanks and liquid gas got into the charcoal canister, and charcoal eventually made its way into the evap lines and clogged the solenoid.

In both cases people managed to clear lines and unstick vent valves using compressed air. Obviously you have to be quite careful using compressed air around gasoline. You don't want to pressurize the tank. And you don't want to create any kind of fuel/air geyser blowing out of a line that would be inflammable.

Some of those valves you describe are probably related to the system which balances the fuel levels across the saddle tank. They are really venturis which work off a pressure differential to move the fuel. description below:

DESCRIPTION AND OPERATION > FUEL SYSTEM DESCRIPTION > FUEL SYSTEM
OVERVIEW

The fuel system is an electronic returnless on-demand design. A returnless fuel system reduces the
internal temperature of the fuel tank by not returning hot fuel from the engine to the fuel tank. Reducing
the internal temperature of the fuel tank results in lower evaporative emissions.
An electric turbine style fuel pump attaches to the primary fuel tank fuel pump module inside the fuel tank.
The fuel pump supplies fuel through the fuel feed pipe to the high pressure fuel pump. The high pressure
fuel pump supplies fuel to a variable-pressure fuel rail. Fuel enters the combustion chamber through
precision multi-hole fuel injectors. The high pressure fuel pump, fuel rail pressure, fuel injection timing,
and injection duration are controlled by the engine control module (ECM).
The primary fuel tank fuel pump module also contains a primary jet pump and a secondary jet pump. Fuel
pump flow loss, caused by vapor expulsion in the pump inlet chamber, is diverted to the primary jet pump
and the secondary jet pump through a restrictive orifice located on the pump cover. The primary jet pump
fills the reservoir of the primary fuel tank fuel pump module. The secondary jet pump creates a venturi
action which causes the fuel to be drawn from the secondary side of the fuel tank, through the fuel

transfer pipe, to the primary side of the fuel tank.

[Goohead]

Thanks Craig,

So finally figured it out. For anyone else that has this issue here are some thought:
Drain the tank, problem I had was the evap related line (brown/orange plug) going to the bottom of the pump runs to a fuel fill valve. Rushing I dropped this line in the tank with fuel, which could have been avoided if you drain the tank. Even if you let the fuel drip out of fitting, there will still be some left, and you have to turn the tank sideways to get out. This was my issue I though I drained it.

Leveler/floater might get stuck on one of the 3 lines that connect to the pump, or a 4th line that runs to the right side of the tank. Make sure to check to see if the floater has full travel without hitting one of these lines. It’s kind of tight so you have to reach in and use your hand and manually move it up and down. If you feel any resistance other than the liquid, even if it’s a little, it might be hitting one of the hoses and you might want to reposition the hoses.

Lastly it is good to just check the Ohms on the lever travel from top to bottom using a multimeter before installing on the new pump. At bottom it ~251, forgot what top was but you can check it against the transfer pump on the other side of the tank.

All in all, bad engineering designs, but hope this helps anyone else with the same issue

[ctrlz]

So, if I understand correctly, a slug of liquid fuel found a low spot in a vent line that should contain only air? And this prevented the tank from venting when you tried to refill it?


These systems with no gas cap have to vent through the EVAP lines and charcoal canister because it is illegal to vent directly to atmosphere.


Nice work. Glad you got it running! And no expensive parts to buy!

[Goohead]

Craig, exactly. The in tank system versus out of tank routing makes servicing a pain.

Appreciate all the help brother!

[Joshinator99]

Good info fellas. I’m sure this will happen to someone else at some point too! Great that the answer will be here.

[BDPhoto519]

On this same topic then...

When installing a new intake manifold such as the HIRam without an evap port provision some people choose to rig up the EVAP solenoid to function still with an added vacuum line and some just cap off the hard line at the firewall and disable the solenoid/codes with HP Tuners.

After reading this, aside from being frowned upon by the emissions police there's really no need to hookup the evap solenoid it seems in the effort to KISS the new intake setup and avoid more lines and potential vacuum leaks. But if you just cap it at the firewall how do the vapors get vented to atmosphere? Also not sure if venting fuel vapors into the engine bay without a cap seems like a great idea either.

Suggestions?

[ctrlz]

Originally Posted by BDPhoto519

But if you just cap it at the firewall how do the vapors get vented to atmosphere? Also not sure if venting fuel vapors into the engine bay without a cap seems like a great idea either.

Suggestions?

After reading about the OP's problem, I think I have a good idea of where all the evap components are, and how they work. I was contemplating a long post describing all this.

But, for now, my answer to your question.
If you disable the purge cycle and cap the purge line by the firewall, the vapors will saturate the charcoal canister and most likely liquid will form in there and degrade the charcoal. This is not good, particularly if you ever want to use the system again.

The charcoal canister sits behind the right rear wheel.
When the tank is being fueled, vapors exit through the fill vent valve (which is inside the gas tank at the top). They travel through a vent tube (also inside the tank) where they make a connection at the fuel pump to the line which leads to the charcoal canister. This line travels over the right rear wheel well, and near the top actually splits in a Y. One leg connects to the fuel fill tube allowing some vapor to be drawn back into the fill tube where it can condense into liquid and drain into the tank. The remainder of vapor goes to the canister where it gets adsorbed by charcoal until the next purge cycle. The Y-split allows Chevy to use a smaller canister.

If you disable purge by HP tuners and cap the line up front. I doubt much vapor would get into the engine bay.
During purge, the purge solenoid by the intake manifold is opened. There is a vent solenoid on the charcoal canister that is also opened. With both solenoids open, there is a clear path to pull the vapors out of the charcoal, into the intake, and let fresh air in. The vent solenoid at the charcoal canister connects to a vent tube with a breather filter that arches up over the right rear wheel well, so the system can never suck up any water or debris during purge, as the canister sits pretty low.

If the evap solenoid is not connected to the charcoal canister or the intake, I don't think it needs a vacuum line.

I don't know why there would be no provision for hooking this up. it's pretty hard to delete all the components to save weight. And purge only runs rarely. there are real emission benefits to using it. So I say use it if you can't get any performance from not using it.

[BDPhoto519]

Thanks Ctrlz, I appreciate the detailed reply and explaining the entire system. I've never really taken the time to learn the detailed ins and outs of the emission systems despite working on cars for a long time now.

Your info helped alot!

Originally Posted by ctrlz

After reading about the OP's problem, I think I have a good idea of where all the evap components are, and how they work. I was contemplating a long post describing all this.

But, for now, my answer to your question.
If you disable the purge cycle and cap the purge line by the firewall, the vapors will saturate the charcoal canister and most likely liquid will form in there and degrade the charcoal. This is not good, particularly if you ever want to use the system again.

The charcoal canister sits behind the right rear wheel.
When the tank is being fueled, vapors exit through the fill vent valve (which is inside the gas tank at the top). They travel through a vent tube (also inside the tank) where they make a connection at the fuel pump to the line which leads to the charcoal canister. This line travels over the right rear wheel well, and near the top actually splits in a Y. One leg connects to the fuel fill tube allowing some vapor to be drawn back into the fill tube where it can condense into liquid and drain into the tank. The remainder of vapor goes to the canister where it gets adsorbed by charcoal until the next purge cycle. The Y-split allows Chevy to use a smaller canister.

If you disable purge by HP tuners and cap the line up front. I doubt much vapor would get into the engine bay.
During purge, the purge solenoid by the intake manifold is opened. There is a vent solenoid on the charcoal canister that is also opened. With both solenoids open, there is a clear path to pull the vapors out of the charcoal, into the intake, and let fresh air in. The vent solenoid at the charcoal canister connects to a vent tube with a breather filter that arches up over the right rear wheel well, so the system can never suck up any water or debris during purge, as the canister sits pretty low.

If the evap solenoid is not connected to the charcoal canister or the intake, I don't think it needs a vacuum line.

I don't know why there would be no provision for hooking this up. it's pretty hard to delete all the components to save weight. And purge only runs rarely. there are real emission benefits to using it. So I say use it if you can't get any performance from not using it.