GC/MS Wont Run in Splitless Mode but Runs in Split Mode

What are the inlet and column configurations, flow rates, pressures, and timing setpoints?  The fastest way to share that is to copy/paste the contents of the file   acqmeth.txt    that lives underneath your specific   Our_Run_Method_Name.M   subdirectory in Windows Explorer.

The 7890A Troubleshooting manual is available G3430-90017.pdf (agilent.com)

Page 97...

Please run the SS Split Vent Restriction Test, page 157, and the Inlet Trap Check, page 155.

Thanks for the comments I have pasted the requested information below:

This is a new one for us as our lab has been running these instruments for 20+ years and can't ever  remember this as a problem. We run trace level organics and almost always  splitless, we tried the split method and was surprised to see it worked fine while the splitless still hangs up.  

We have dual columns set up on the back inlet with one running to the MS and one running to an FID and are using a double tapered, splitless, inlet liner.   Here's one method:

I also went ahead and ran the inlet trap check with a flow rate of 400 mL/min and it resulted in a inlet pressure of 0.946 psi, which seems lower than what it should be based on the values provided in the manual for a clean split flow path.  We were again using a double tapered, splitless, inlet liner. Would this have an impact even though we are having issues in splitless mode?   I also went ahead and ran an inlet leak test and it is resulted in a total flow of 0 compared to the column at 3.61.  Is this pointing towards a flow restriction in a gas line? Thanks!

Recommendations:

Increase the Oven Temperature equilibration time from 0.5 minutes to 1 to 1.5 minutes. The GC oven walls need more time to cool down from 300° C back to 50° C to be ready for the next run. This affects run-to-run reproducibility.

The starting inlet pressure is only 1.7232 psi of hydrogen - which is less than the >5 psi minimum for decent flow/pressure control. This also means that column 2 flow is only 0.318 ml/min - in a 0.32 mmid column that is far below the optimal linear velocity for good chromatography. 

This 1.7232 psi is for 1.6 ml/min of hydrogen carrier gas flow into the MS. The system's pumping speed for hydrogen is only 60% that for helium. The optimal flow into the ion source using hydrogen is 0.4 to 1.0 ml/min.

The Gas saver is set to 20 ml/min after 2 minutes - AND the Purge flow to split vent is set to 45 ml/min at 2 minutes.  So the Spltless liner purge flow doesn't happen, the inlet just goes to Gas Saver mode at 20 ml/min.  2 minutes for Purge Flow to Split Vent is long with the column flows you have configured anyway. The liner volume is ~800µL and at your current flows, 1.6+0.32= 1.92, the liner is swept in ~ 25 seconds so the typical Purge Flow to Split Vent time for Splitless for that would be like 50 at 0.5 minutes.

When did you switch to hydrogen carrier gas?  Do you use tanks or a hydrogen generator?

The inlet test results in the manual were written with helium in use. 400 ml/min of hydrogen is easier to push than 400 ml/min of helium so the lower pressure in the trap test is typical.  During the inlet leak test if total flow went to zero there was no flow in the inlet.   What is your hydrogen supply pressure?  Are there traps on the line?  If you use a hydrogen generator is there moisture in the supply lines - that can damage the electronic pressure control modules.

What parts are being used to install two columns to the inlet?  Remove both columns, reinstall only the one to the MS, configure and save a method with those parameters, and check again.

This column configuration is an issue using hydrogen carrier gas.  I would recommend that with hydrogen carrier gas you change to 2 x  20m×180µm columns with column 1 at 0.9 ml/min, 7.7939 psi inlet, and column 2 would be 0.5157 ml/min, good for a 180µm column.

Recommendations:

Increase the Oven Temperature equilibration time from 0.5 minutes to 1 to 1.5 minutes. The GC oven walls need more time to cool down from 300° C back to 50° C to be ready for the next run. This affects run-to-run reproducibility.

The starting inlet pressure is only 1.7232 psi of hydrogen - which is less than the >5 psi minimum for decent flow/pressure control. This also means that column 2 flow is only 0.318 ml/min - in a 0.32 mmid column that is far below the optimal linear velocity for good chromatography. 

This 1.7232 psi is for 1.6 ml/min of hydrogen carrier gas flow into the MS. The system's pumping speed for hydrogen is only 60% that for helium. The optimal flow into the ion source using hydrogen is 0.4 to 1.0 ml/min.

The Gas saver is set to 20 ml/min after 2 minutes - AND the Purge flow to split vent is set to 45 ml/min at 2 minutes.  So the Spltless liner purge flow doesn't happen, the inlet just goes to Gas Saver mode at 20 ml/min.  2 minutes for Purge Flow to Split Vent is long with the column flows you have configured anyway. The liner volume is ~800µL and at your current flows, 1.6+0.32= 1.92, the liner is swept in ~ 25 seconds so the typical Purge Flow to Split Vent time for Splitless for that would be like 50 at 0.5 minutes.

When did you switch to hydrogen carrier gas?  Do you use tanks or a hydrogen generator?

The inlet test results in the manual were written with helium in use. 400 ml/min of hydrogen is easier to push than 400 ml/min of helium so the lower pressure in the trap test is typical.  During the inlet leak test if total flow went to zero there was no flow in the inlet.   What is your hydrogen supply pressure?  Are there traps on the line?  If you use a hydrogen generator is there moisture in the supply lines - that can damage the electronic pressure control modules.

What parts are being used to install two columns to the inlet?  Remove both columns, reinstall only the one to the MS, configure and save a method with those parameters, and check again.

This column configuration is an issue using hydrogen carrier gas.  I would recommend that with hydrogen carrier gas you change to 2 x  20m×180µm columns with column 1 at 0.9 ml/min, 7.7939 psi inlet, and column 2 would be 0.5157 ml/min, good for a 180µm column.