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The Bobcat T650 is a popular compact track loader known for its power, versatility, and reliability. Yet even the most dependable machines can suffer from fuel‑delivery issues, especially as they age or operate in dusty, debris‑heavy environments. One of the most frustrating problems owners encounter is intermittent stalling caused by fuel starvation. This issue often presents itself as a collapsed primer bulb, inconsistent engine performance, or sudden shutdowns under load.
This article explores the root causes of fuel blockage in the Bobcat T650, explains the engineering behind its fuel‑pickup system, and provides practical solutions—including a creative field repair that restored full functionality. Along the way, terminology notes, industry stories, and additional recommendations help paint a complete picture of how to diagnose and resolve this common issue.
Understanding the Bobcat T650 Fuel System
The T650 uses a straightforward diesel fuel system designed for durability and ease of service. Key components include:
Symptoms of Fuel Blockage
Owners typically report:
Why the Blockage Occurs
According to the retrieved information, newer Bobcat machines no longer use a screen on the pickup tube. Instead, they rely on a simple rigid poly tube. While this design reduces clogging from fine sediment, it increases vulnerability to larger floating debris.
Common causes include:
Why the Primer Bulb Collapses
A collapsed primer bulb is one of the most reliable indicators of upstream blockage. It means:
Testing for Tank Venting Issues
One suggestion from an experienced mechanic was to run the machine with the fuel cap loose. This test checks for vacuum lock caused by a blocked tank vent.
If the machine runs normally with the cap loose, the vent is likely obstructed. If the problem persists, the blockage is inside the tank or pickup tube.
Accessing the Pickup Tube
On the T650, the pickup tube is located on the left side when viewed from the front. Access requires lifting the cab, but it is not considered a difficult task by technicians familiar with the machine.
However, in some models—such as the Bobcat T590—the pickup tube is positioned under the engine, making access extremely limited. One owner reported being able to touch it with a finger but not remove it, complicating repairs.
A Creative Field Repair That Solved the Problem
When the pickup tube could not be located or removed, one owner devised an innovative solution:
This approach bypassed the original pickup tube entirely and eliminated the hidden blockage.
Additional Recommendations
To prevent future blockages:
A Story from the Industry
A contractor in Texas once battled a similar issue on a compact track loader. After weeks of intermittent stalling, the culprit was found to be a small piece of rubber from a deteriorated fuel‑cap gasket. It floated freely until suction pulled it against the pickup tube. When the engine shut down, the debris drifted away—making the problem nearly impossible to diagnose without draining the tank.
Stories like this highlight why fuel‑system blockages can be so frustrating: the debris often moves unpredictably.
Why Bobcat Removed the Pickup Screen
Older Bobcat models used a fine mesh screen at the end of the pickup tube. While effective at blocking debris, the screen often clogged and caused fuel starvation. Removing the screen reduced maintenance but increased the risk of larger debris entering the system.
This design trade‑off is common in modern equipment: fewer service points, but higher sensitivity to contamination.
Conclusion
Fuel blockage in the Bobcat T650 is a common but solvable issue. The combination of a rigid pickup tube, lack of a screen, and potential tank contamination creates conditions where debris can intermittently restrict fuel flow. A collapsed primer bulb is the clearest sign of upstream blockage, and solutions range from simple vent‑cap testing to full pickup‑tube replacement.
In cases where the pickup tube is inaccessible, installing a new screened pickup tube through a fresh opening in the tank can restore reliable operation. With proper maintenance and awareness of contamination risks, the T650 can continue delivering strong performance in demanding environments.
This article explores the root causes of fuel blockage in the Bobcat T650, explains the engineering behind its fuel‑pickup system, and provides practical solutions—including a creative field repair that restored full functionality. Along the way, terminology notes, industry stories, and additional recommendations help paint a complete picture of how to diagnose and resolve this common issue.
Understanding the Bobcat T650 Fuel System
The T650 uses a straightforward diesel fuel system designed for durability and ease of service. Key components include:
- A rigid pickup tube inside the fuel tank
- A primer bulb for manual fuel priming
- Fuel lines routed to the lift pump and filters
- A return line to maintain circulation
- A vented fuel cap to prevent vacuum buildup
- Primer Bulb: A hand‑squeezed bulb that draws fuel from the tank to prime the system. A collapsed bulb indicates suction blockage.
- Pickup Tube: A rigid tube inside the tank that draws fuel from the bottom.
- Fuel Starvation: A condition where the engine does not receive enough fuel to maintain combustion.
- Vacuum Lock: A condition where the tank cannot vent properly, causing suction to collapse the fuel line.
Symptoms of Fuel Blockage
Owners typically report:
- Random stalling
- Engine shutting down under load
- Primer bulb collapsing flat
- Machine restarting only after blowing compressed air backward through the fuel line
- Debris appearing in the fuel filter after treatment additives
Why the Blockage Occurs
According to the retrieved information, newer Bobcat machines no longer use a screen on the pickup tube. Instead, they rely on a simple rigid poly tube. While this design reduces clogging from fine sediment, it increases vulnerability to larger floating debris.
Common causes include:
- Plastic fragments from deteriorating tank components
- Organic debris such as leaves or insects
- Fuel‑tank contamination from dirty fuel cans
- Residue loosened by fuel‑system cleaners
- A collapsed or deteriorated grommet at the pickup‑tube elbow
Why the Primer Bulb Collapses
A collapsed primer bulb is one of the most reliable indicators of upstream blockage. It means:
- The lift pump is trying to pull fuel
- Fuel cannot reach the pump
- Suction increases until the bulb flattens
Testing for Tank Venting Issues
One suggestion from an experienced mechanic was to run the machine with the fuel cap loose. This test checks for vacuum lock caused by a blocked tank vent.
If the machine runs normally with the cap loose, the vent is likely obstructed. If the problem persists, the blockage is inside the tank or pickup tube.
Accessing the Pickup Tube
On the T650, the pickup tube is located on the left side when viewed from the front. Access requires lifting the cab, but it is not considered a difficult task by technicians familiar with the machine.
However, in some models—such as the Bobcat T590—the pickup tube is positioned under the engine, making access extremely limited. One owner reported being able to touch it with a finger but not remove it, complicating repairs.
A Creative Field Repair That Solved the Problem
When the pickup tube could not be located or removed, one owner devised an innovative solution:
- Drill a new hole near the tank’s vent line
- Install a new screened pickup tube
- Route a new fuel line directly to the filter
This approach bypassed the original pickup tube entirely and eliminated the hidden blockage.
Additional Recommendations
To prevent future blockages:
- Keep fuel cans clean and sealed
- Replace the fuel cap if the vent is questionable
- Periodically drain the tank to remove sediment
- Avoid using aggressive fuel‑system cleaners unless necessary
- Install an inline pre‑filter if contamination is recurring
- Inspect grommets and elbows for deterioration
A Story from the Industry
A contractor in Texas once battled a similar issue on a compact track loader. After weeks of intermittent stalling, the culprit was found to be a small piece of rubber from a deteriorated fuel‑cap gasket. It floated freely until suction pulled it against the pickup tube. When the engine shut down, the debris drifted away—making the problem nearly impossible to diagnose without draining the tank.
Stories like this highlight why fuel‑system blockages can be so frustrating: the debris often moves unpredictably.
Why Bobcat Removed the Pickup Screen
Older Bobcat models used a fine mesh screen at the end of the pickup tube. While effective at blocking debris, the screen often clogged and caused fuel starvation. Removing the screen reduced maintenance but increased the risk of larger debris entering the system.
This design trade‑off is common in modern equipment: fewer service points, but higher sensitivity to contamination.
Conclusion
Fuel blockage in the Bobcat T650 is a common but solvable issue. The combination of a rigid pickup tube, lack of a screen, and potential tank contamination creates conditions where debris can intermittently restrict fuel flow. A collapsed primer bulb is the clearest sign of upstream blockage, and solutions range from simple vent‑cap testing to full pickup‑tube replacement.
In cases where the pickup tube is inaccessible, installing a new screened pickup tube through a fresh opening in the tank can restore reliable operation. With proper maintenance and awareness of contamination risks, the T650 can continue delivering strong performance in demanding environments.
