Diagnosis And Testing - Hard To Fill With Fuel

Courtesy of CHRYSLER GROUP, LLC

Courtesy of CHRYSLER GROUP, LLC

Courtesy of CHRYSLER GROUP, LLC

We are all familiar with the handle we squeeze to get fuel to exit the nozzle. The shut off is created by an aspirator or sensing port located underneath the end of the nozzle and when fuel covers the sensing port, the nozzle shuts off.

When the fuel pump nozzle is placed in the filler cup and triggered on, fuel flows down the fill pipe. Air from the outside of the filler cup is also drawn into the filler cup due to vacuum created by the fuel flow. The air and fuel flow into the fuel tank through the Inlet Check Valve (ICV), the valve that is welded to the fuel tank and creates the connection between the fill hose and fuel tank shell. Fuel displaces the vapor in the fuel tank, fuel vapor and the entrained air from the outside flow out of the fuel tank through the Fill Limit Vent Valve (FLVV) or a Control Valve (CV) if so equipped. The Control Valve has an internal component (diaphragm) that communicates with atmosphere through the recirculation line when the fuel cap is removed prior to refueling. The recirculation line must be free of debris, liquid or any other type of blockage in order to create the communication link. The confirmation of this link will permit the diaphragm to rise off of the main venting orifice allowing fuel vapor to exit the fuel tank.

That fuel vapor flows from the FLVV / CV through the canister line and into the evaporative canister where the hydrocarbons attach to the charcoal in the evaporative canister and fresh air exits the evaporative canister. The fresh air travels past the Evaporative System Integrity Monitor (ESIM) and through the air line and exiting the fuel system through the fresh air filter. Once the fuel level reaches full, there is a refueling float in the FLVV / CV which closes the main vapor venting orifice. The closure of this orifice prevents fuel vapor from exiting the fuel tank. The pressure in the fuel tank rises rapidly and fuel fills the filler pipe. When the fuel hits the aspirator valve in the fuel fill nozzle the fuel flow is shut off.

Every element that fuel and vapor flow through results in additional back pressure during refueling. When functioning properly, the back pressure is low enough that the fuel in the filler pipe does not rise high enough to cover the sensing port and shut off the refueling nozzle.

When a hard to fill condition is present, something has happened to cause an increase in system back pressure. The back pressure rises to the point where the fuel height in the filler pipe covers the aspirator and shuts off the fuel nozzle, or the customer can only get fuel into the tank at a very slow rate due to the additional back pressure restriction.

The "Hard to Fill" diagnostic procedure focuses on trying to efficiently identify what has created the increase in back pressure creating the hard to fill condition.

There can also be problems with fuel station nozzles and operator procedure, such as not putting the nozzle into the filler pipe properly. This can result in a hard to fill condition where constant fuel flow is not able to be established. As the customer gets used to their vehicle, the owner typically figures out the proper nozzle insertion. An issue with the fuel pump nozzle would be intermittent when they pull up to a pump with a bad nozzle, unless they always refuel at the same station / same pump and it happens to have a bad nozzle.

DIAGNOSTIC PROCEDURE 

1. Verbally confirm customer complaint.
   • Has the vehicle always had the "Hard to fill fuel" issue, or is it recent?
   • Does it occur on all fill ups or is it intermittent?
   • Is the issue only on high flow and is it okay on low flow of the fuel pump?
   • When the customer fills their vehicle, does the fuel pump shut-off after a few seconds, or after a few gallons?
     1. If the answer to this question is after a few seconds, proceed to Step 2.
     2. If the answer to this question is after a few gallons, proceed to Step 3.
2. Nozzle Sensitivity  - The customer could be experiencing a known nozzle sensitivity issue due to various types and conditions of nozzles, nozzle insertion variation, as well as differences in gas pump flow rates. Before replacing any parts  , please follow the steps in this service information to help determine if this is the case.

   As information, shutoff is created by an aspirator or sensing port located inside the end of the nozzle. When fuel covers the sensing port, the nozzle shuts off.

   • If possible, verbally ask the customer:
     1. What station and pump number do the premature shutoff(s) occur at?
     2. How often do the premature shutoffs occur? (Immediate shutoffs would indicate the customer is experiencing the nozzle sensitivity issue)
   • If possible, take the customer to the gas station and gas pump to demonstrate the premature shutoff condition.
     1. Make sure that the fuel nozzle is being fully inserted to open both doors of the capless unit and try to fill the vehicle with fuel.
     2. If premature shutoffs occur in step "a", back up the nozzle approximately 1/2 " and determine if the premature shutoffs continue to occur.
     3. If premature shutoffs occur in step "b", rotate the nozzle to multiple angular positions and determine if the premature shutoffs continue to occur.

     If you or the customer can refuel the vehicle without premature shutoffs by repositioning the nozzle as described above, then the customer is experiencing the nozzle sensitivity issue and no parts should be replaced on their vehicle.

     Please explain to the customer that this is a known issue and recommend that they try different nozzle insertions depths and angular orientations, along with trying different pumps within the same gas station until a permanent corrective action is implemented and available (~4th quarter 2017).

     If following the procedure above does not resolve the customers concerns, then proceed to Step 3.

3. Scan and record any fuel related P Codes.
   • Were any problems found?
   • No  - Continue to Step 4.
   • Yes  - Address P code and proceed to Step 11 - Fuel Fill Verification.
4. Capless Fill Cup Check  - (if the vehicle has a capped fill cup please proceed to step 5) check the fill house, fill door and capless fill cup area for any type of contamination (dirt, dust, etc.). Visually examine the capless fill cup and confirm with an emergency funnel or a fill nozzle that the external door, internal door and nozzle flow guide are present and functioning correctly. The insertion of the tool used to examine the capless fill cup should pass the first and second door with very little resistance or difficulty. The ability to determine the presence of the nozzle flow guide will be difficult. The implementation of the nozzle flow guide was launched on April 11th, 2016. If the vehicle build date is before this date the filler tube assembly does not have a nozzle flow guide.
   • Were any problems found?
   • No  - continue to step 4
   • Yes  - for a capless fill cup issue, replace the entire fill pipe assembly, document the issue with the capless fill cup on the repair order and proceed to Step 11 - Fuel Fill Verification
5. Line Check  - Put vehicle up on hoist and examine visually, by feel or mirror to look for a kink, bend, or twist condition in the Fill Hose, Air Line, Recirculation Line, or Canister Line. Check that the Air Line is connected to both the ESIM and the Air Filter.
   • Were any problems found?
   • No  - Continue to Step 5
   • Yes  - For a disconnected Air Line, replace the ESIM and Canister and proceed to Step 11. For a kink, bend or twist, straighten or replace as necessary, document on the repair order, and proceed to Step 10 - Fuel Fill Verification
6. Air Filter Check  - Disconnect the air filter and tap it on a table to determine if the air filter is dirty or plugged.
   • Were any problems found?
   • No  - Continue to Step 6
   • Yes  - Replace Air Filter. Remove the gas cap and tap it on the table to see if it is dirty and replace it if it is. Proceed to Step 11 - Fuel Fill Verification
7. Recirculation Line Check  - Remove the recirculation line from the fill neck and remove the large fill hose at the fuel tank. The gas cap should still be on. Blow air into the recirculation line and air with no contamination should flow freely out of the fill large fill hose.
   • Were any problems found?
   • No  - Continue to Step 7
   • Yes  - Replace fuel filler neck and proceed to Step 11 - Fuel Fill Verification
8. Fuel Tank Inlet Check Valve (ICV) Check  - The fill hose should already be removed from the ICV. Visually look inside the ICV for an obstruction. If obstructed, remove the object if possible. Using a long thin object (not a screwdriver) that will not damage the seal on the check valve or the anti-siphon features inside the ICV, push the object into the ICV to verify that it is free of obstruction. There is a spring behind it, so there will be a little resistance, but it should move freely and not be sticky.
   • Were any problems found?
   • No  - Continue to Step 8
   • Yes  - If an obstruction was found, but the ICV moves freely proceed to Step 11 Fuel Fill Verification. If the ICV does not move freely, replace the fuel tank and proceed to Step 11 - Fuel Fill Verification
9. Reassemble the components removed in earlier steps.
10. EVAP System Check  - Disconnect the canister line on the fuel tank multifunction control valve (MFCV). Take the vehicle to the gas station and determine if it fills cleanly.
    • Fuel tank fills clean - Replace the evaporative canister and ESIM assembly and refuel to verify problem solved.
    • Still Hard to Fill - Return to Step 2 - Nozzle Sensitivity
11. Fuel Fill Verification  - Take the vehicle to the gas station and determine if it fills cleanly.
    • Fuel tank fills clean - Problem found and complete
    • Still Hard to Fill - Return above to the step below where you found an issue and continue diagnostic.