Troubleshooting Vacuum & Pump Issues

In this video, we’re going to review some simple troubleshooting procedures you can use to diagnose and fix pump issues your truck may be experiencing while out in the field.

Low Suction:

The first few troubleshooting tips we’ll review in this video revolve around having minimal suction on your truck. If you’re experiencing a complete loss of suction, please skip ahead to the “No Suction” troubleshooting tips.

Possible Issue #1: Low RPMs

A common pump issue that can often occur on older trucks with older vacuum pumps is low suction. Unlike the newer trucks in our fleet, they are not equipped with an automatic PTO governor which throttles the engine up automatically when the PTO is engaged.

To rectify this issue on older trucks, we’ll need to put the truck in park with the parking brake on. We’ll then activate the truck’s PTO. Next, we’ll make sure our foot is off the gas and enable the cruise control by pressing the cruise button on the top left of the steering wheel. We’ll then press the set button at the top right of the steering wheel. Lastly we’ll hold the bottom right button to turn up the RPMs. A good rule of thumb is to keep the trucks RPM between 1000 – 1100 RPMS. Once we’ve locked in the RPMs, you should have the appropriate amount of suction for the job. If that doesn’t work though, we’ll continue on…

Possible Issue #2: Both Valves on Truck Open

After we’ve established the correct RPMs for our pump, the next thing we’ll check is to make sure we don’t have two inlet valves open at the same time. If both valves are open the suction power is cut in half and not nearly as effective. If both valves are open, simply close the valve on the side of the truck that’s not being utilized to restore full pressure. If this doesn’t rectify the issue continue on…

Possible issue #3: Bad “O” Ring

If you happen to experience low pressure throughout the day and there’s a high-pitched hissing sound coming from your hose connection coming from one of your hose there’s a good chance you may have an “O” ring that needs to be replaced. Unfortunately, the only way to fix this issue is to have the O-ring replaced back at the shop. In situations like this, it’s best to note it on your post-trip paperwork and then consider using the hose on the other side of your truck until the issue is rectified. If you’re still having suction issues we’ll continue on.

Possible issue #4: Vacuum/Pressure Valve Not Locked In

If all checks out thus far, we’ll next need to check the vacuum/pressure valve located on top of the pump. On occasion, this large valve can work itself loose if throughout the day. If that were to happen, we’d certainly experience a loss of suction. To rectify, we’ll simply need to push the lever into the vacuum position until it no longer moves. If this were causing the issue, vacuum suction should quickly resume. If not, we’ll need to continue on


No Suction:

The next few tips we’ll review in this video revolve around having a complete loss of suction on your truck so let’s get started.

Possible Issue #1: Full Truck

If the truck you’re using was pumping fine and then suddenly stops, it may be because the waste tank is full. The first thing we’ll need to check is the site bubble on the side of the truck. If the bubble near the top of the tank is no longer clear, it means the waste tank is full. Another way to test is by tapping the side of the truck with a piece of rebar or some other solid object to listen for the sound of a full or empty tank. A full tank sounds more like a thud, while an empty tank sounds more like a gong. If the tank is full, you’ll need to notify dispatch of the issue and await further instructions. If not, we’ll continue with troubleshooting tip #2.

Possible Issue #2: Clogged Line

Once we’ve confirmed the truck still has room, the next thing to check for is if we may have sucked up something that’s now clogging your line. To rectify this issue, we’ll first need to remove the wand and investigate it to see if we can visually see a clog. If a clog is spotted, we’ll need to clear it using a TP rod, scrub brush handle, or even a plyers on our truck. If the wand appears clear from obstructions, we’ll then need to inspect the hose.

To inspect the hose, we’ll first look into the end that was connected to the wand to identify any potential obstructions. If there are no obstructions, we’ll remove the other end of the hose where it’s connected to the truck. Always, I repeat always check the connection by the truck without first inspecting the wand. This is because if there’s a clog near the wand, the hose may still be backfilled with waste; therefore, when you disconnect that end by the truck you may end up getting a shower you won’t soon forget.

If there’s some resistance when trying to remove the hose from the truck, it may still have negative vacuum pressure inside it, indicating a clog is in the hose. However, if there’s no resistance, continue removing the hose from the truck. Once the hose is separated with the PTO engaged, we’ll slowly open the valve at the truck. If there’s vacuum pressure at the valve, we now know the clog is for sure located somewhere in the hose. We’ll then close the valve and investigate each end of the hose that was connected to the truck to locate any obstructions.

If we can’t find any obstructions, we’ll take the end of the hose that was connected to the wand and connect it to the valve on the truck. This will reverse the airflow in the hose to loosen up whatever may be wedged inside. We’ll once again open the valve on the truck and wait a moment to see if there’s any difference.

If the hose begins to move, it means the clog is freeing itself and moving into the truck. If the clog doesn’t free itself on the first try, we’ll need to repeatedly switch the hose ends that are connected until the obstruction is ultimately vacuumed into the truck or pulled to one end of the hose where we can remove it manually. Once the clog is clear, we’ll reconnect all equipment to its original locations. If we’re unable to unclog our hose, we can attempt to swap the hose from the other side of the truck and note the clogged hose on our Post-Trip paperwork so a mechanic can further diagnose it in the evening. If we’re without an additional hose, we’ll need to contact dispatch and await further instructions.


Possible Issue #3: Oil Separator full/ Secondary Tank Full

Once we’ve confirmed our truck’s holding tank has room and there are no clogs in the hose, we’ll want to inspect our secondary trap and oil separator tanks. Both tanks are used to catch any runoff waste or oil that may have occurred while in transport. It’s important to know that these tanks will often need to be drained every 2-3 days to keep your truck’s vacuum system running properly. This task is often performed by our yard team; however, some branches may have their drivers complete this task.

We’ll start by locating our secondary trap. Once located, we’ll need to place a bucket under the secondary trap and open the valve on the bottom of the tank. Lastly, we’ll need to put the pump into the neutral position so air can flow back into the system, allowing the tank to fully drain. If we notice a large amount of fluid exit the tank this may have been what was causing our low suction issue.

Once this tank has drained, we’ll move on to drain the oil separator. This is often located next to your pump and has a valve on it as well. Once the tanks are drained, we’ll close both valves and, flip it from neutral to pressure, and retest the system to see if suction has resumed. If it has, we’ll proceed to suck up anything in the bucket and return to our route. If you’re still having issues, please continue on..

Possible Issue #4: Broken PTO Sleave

Finally, if all else fails and you’ve confirmed your truck has room and your hoses are clear and functional, we’ll need to check your truck’s PTO sleeve. A PTO sleeve is safety device designed to break free if there are issues with the PTO or pump. Once it breaks the truck’s vacuum system will no longer receive power from the engine. One sign you may be dealing with a broken PTO sleeve is a burning rubber smell or smoke which is radiated from behind the truck’s cab where friction is occurring.

If this occurs while on route, there’s nothing you’ll be able to do to rectify the issue. You’ll need to contact dispatch at this point who will then direct you to the mechanic team who will most likely work to get you a new truck to finish your day.