Shop Vac Not Suctioning Well? (11 Causes & 11 Solutions!)

Shop Vac Not Suctioning Well (Causes & Solutions)

There can be disappointments when your Shop-vac seems not to be doing one of its most important jobs- Suction. This problem could be present as irregular noise and the inability to pick up dirt at all or pick it up well enough.

A shop vac not suctioning well can be caused by issues ranging from dirty primary or secondary filters, and clogs at some strategic parts of the hose to dirty suction blades.

In this article, you’ll understand the possible reasons why your shop vac is not suctioning well. We would also look at solutions and other important things regarding shop vac suction.

Shop Vac Not Suctioning Well

Shop-vac is one of the best investments you will make if you have a lot of work that suits its function in your shop or even at home. The poor suction power of your vacuum can be annoying and needs to be immediately taken care of.

11 Reasons Why Your Shop Vac Has Poor Suction

Several reasons why the shop vac has issues with suction are related to clogs. Below are some of those reasons:

1- Dirty Air Filter

This could be the primary or secondary filter. When the air filters are full of dust and debris, air can’t get through leading to poor suction.

The secondary filter getting clogged is dependent on the primary filter. When the primary filter has holes or tears, it allows larger particles to get to the secondary filter thereby clogging it and blocking the airflow.

So, check both primary and secondary filters.

2- Plastic Bag Getting in the Way

The plastic bag is used to help collect finer dust and help keep the filter clean. When it’s full, it can get in the way of the entrance port and cause the shop vac to lose suction.

3- Blocked Hose

When a hose is blocked, air cannot pass through and there would definitely be no suction.

The two ends of the hose are most often the culprit, but dirt can also get lodged along the hose walls (inside) and prevent suction.

Water bottle covers can easily get lodged in the u-shaped end of the hose that fits into the shop vac tank, while materials like socks can block the other end.

4- Filled Tank

When the shop vac is filled during a cleaning process, the dirt blocks the suction portal leading to poor or no suction.

5- Bad Motor

A bad motor can be caused by dust getting into and clogging it, the shop vac getting rained on and water damaging the motor or, other electrical reasons.

When the motor is bad, the shop vac definitely loses suction.

6- Dirty Impeller/Fan

The fans are located on the head of the shop vac, the area where you also find the motor.

Dirt, debris, and congealed dust can cause the fan to malfunction, causing minimal or no suction. The fan can also lose a screw and this can cause it to malfunction.

7- Holes in the Hose

When there are holes along the length of the hose, the air is lost from those holes and therefore suction will be minimal.

8- Bad Compressor

The compressor is supposed to compress air getting into the vac. But when the compressor is bad, it can make the shop vac lose suction power.

9- Bad/Old Seal

The seal can be found at the rim of the inner side of the bucket cover or shop vac head. It is whitish and rubbery.

When it gets old, it can slack and cause air to escape from the shop vac even when it’s tightly closed. The air loss ultimately leads to poor suction.

10- Shop Vac Getting Wet

If a shop vac gets rained on, the water could mix with the dust piled in the filter, forming congealed masses that clog the filters, making it difficult to vacuum.

Rainwater can also seep into the shop vac and damage the motor and other important parts.

11- Dents on Lid Rim

Dents lodging on the rim of the lid can cause the shop vac not to close properly, leak out air, and lose suction.

Problems Caused by Shop Vac Not Suctioning Well

1- The motor will be weakened because it is trying to do more work than it should. If used in this state for a long time, the motor can go bad, adding to the issue at hand.

2- There would be more noise, as the motor is revving up, which can be very annoying to you and your neighbors.

3- Time and money will be wasted on replacing filters and bags, and using the services of an electrician.

How to Fix Suction on Shop Vac?

1- Dirty Filters: Open up the shop vac and take out the primary and secondary filters.

For Secondary Filter:

These can be seen just after the primary filter, towards the part that houses the motor.

Clean the secondary filter by gently dislodging the dirt trapped on it and then rinse with water and allow to air dry thoroughly.

For Primary Filter:

 Paper Filter: Tap it inside the shop vac, in a trash can, or outside. If it’s very dusty, run an air hose or water hose through it. Leave to air dry for a day or use a hairdryer on medium heat to thoroughly dry it.

Foam Filter: You can also tap it on a firm surface or rinse it with water. Squeeze out as much water as possible from the filter, then leave on a warm flat surface to air dry for a day or use a hairdryer on medium heat if you cannot wait 24 hours.

Putting a bag in the shop vac while using helps to keep the filters clean. Also using dust deputy helps eliminate filter clogging and suction loss.

2- For Plastic Bags Getting in the Way: The bag usually gets in the way when it’s full, so ensure you check and empty the bag often.

3- Blocked Hose: Try running the shop vac without the hose to determine if it is a hose problem. If it is a hose problem, then take the following steps:

a. Check the head of the hose attached to the shop vac and dislodge any materials there.

b. Check the other head that picks up dirt, as cotton materials and plastics can block it.

c. Check along the length of the hose by flashing a light from one end. If you can’t see the light at the other end, then it’s clogged. A few long pokes and shakes can get stuck dirt out.

Also, run water with a garden hose through the disconnected hose to get out all the crud.

4- Bad Motor: When a motor is bad, you would hear a different sound than usual coming from the shop vac.

a. If you can, disassemble the motor area and remove dust around the vents (if they are clogged).

b. If it was caused by rain or water, tip the shop vac over and allow it to air dry for 24 hours or use compressed air to dry the motor compartment.

c. It could also be that the motor is old and needs replacement.

5- Dirty Impeller/Fan: Remove the cowl (the protective covering for the engine) to reveal the impeller. These often have several blades spaced closely together.

If there are no major blockages around the impeller, probe the inside of the segments with a strip of wire to push out any dirt lodged there.

Take the impeller to the sink and wash and dry thoroughly and put it back in the shop vac.

6- Dents on Lid Rim: This can be brushed out or hammered out if it’s a strongly lodged dent.

7- Full Tank: Always empty the shop vac after each use or during use when you are working with large waste.

8- Bad/Old Seal: This can be solved by buying a weather stripping and fixing it around the circumference of the lid’s inner rim.

9- Got Wet: Take out the filters, clean and air-dry or with compressed air. Disassemble the rest of the shop vac and dry with compressed air, or tip the shop vac upside down and let dry for 24 hours.

10- Holes in the Hose: Flashing light into the hose will reveal the areas with holes. Seal the holes up with gum or tape or you can as well buy a new hose.

11- Bad Compressor: You might want to consider changing the compressor if it cannot be fixed.

Shop Vac Not Picking up Water (Reasons+ Solutions!)

In addition to the above reasons why a shop vac would not perform well, there could be additional reasons when dealing with water as shop vacs are also used in cleaning pools.

Some of these reasons and their solutions are:

1- There is a check valve that acts to block the suction portal when the shop vac is filled with water. So, if your shop vac stops picking up water, it might be full and needs emptying.

2- Sometimes without the shop vac being full, the check valve can tip and give the impression of being full, which stops suction.

Either take out the check valve ball or put a 10lbs weight lifting plate in the bottom of the vacuum. It changes the center of gravity and makes the valve more stable.

3- The u-shaped part where the hose fits into the shop vac might be turned in the wrong direction.

There are different directions for wet and dry use. Check your user manual for the correct direction for wet use.

4- You might be using the wrong type of filter. Check that you are using the right filter to avoid unnecessary clogging.


Many people abandon or trash their shop vacs because of poor or no suction. Most of the suction issues as you have read are linked to poor maintenance and inadequate information.

You can save yourself some bucks by always checking your user manual for troubleshoots, and carrying out routine cleaning and maintenance on your shop vac

2 thoughts on “Shop Vac Not Suctioning Well? (11 Causes & 11 Solutions!)”

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