100TECH Fuel Sending Unit 240-33 ohms 10in - Durable Marine Sender

In this review the 100TECH Fuel Sending Unit is assessed as a practical replacement sender for boat, truck and RV fuel tanks where a reliable, corrosion resistant sensor is needed. The bottom line: installers and boat owners who want a durable, low-maintenance level sender will appreciate the reed switch design and stainless steel construction, which together deliver accurate 240-33 ohm output without the delicate moving arms found on older units. It is especially useful when fitting to existing SAE 5-hole mounts and when a rugged sensor is preferred over thin-film swim arms.

Key Features

• Reed switch core: Uses an OKI reed switch imported from Japan for long-term durability and reduced wear compared with thick-film swim arm units.
• Standard output: Provides American standard 240-33 ohm response (240 ohm empty, 33 ohm full) for straightforward compatibility with most gauges.
• Stainless steel construction: Heavy duty 316 stainless steel and rugged construction resist corrosion in marine and automotive environments.
• Easy installation: Ships with a gasket, mounting screws and illustrated instructions so wiring and mounting follow a clear, simple process.
• Multiple lengths available: Offered in lengths up to 32in and additional sizes on request, letting you match common tank depths.
• Float size and fit: Float diameter is 1.38in and if a hole must be drilled, a 1.50in hole will accommodate the unit cleanly.

Who It's For

The 100TECH sender is aimed at marine owners, RV owners and vehicle technicians who need a reliable replacement for arm type senders and want a product built to resist corrosion and mechanical failure. It fits applications where the SAE 5-hole mounting pattern is used and where a standard 240-33 ohm gauge interface is required.

It is less suitable for tanks that require custom non-standard outputs, very shallow tanks where the sender might contact the bottom, or installations that demand proprietary electronic interfaces. Measure from the top of the tank to the bottom and subtract 1in before selecting the sender length to avoid contact with the tank bottom.

Pros & Cons

Pros

• Durable reed switch design reduces moving parts and long-term failure risk.
• Solid 316 stainless steel construction and well-made welded joints praised by customers for build quality.
• Clear 240-33 ohm output that integrates with standard gauges and is easy to wire.
• Includes gasket and screws with illustrated instructions for straightforward installation.

Cons

• Requires correct length selection; must subtract 1in from tank depth to avoid bottom contact.
• Float diameter and mounting hole size may require drilling or modification on some tanks.

Specifications

Brand	100TECH
Output	240-33 ohm (240 empty, 33 full)
Length	10in (250mm) standard; other lengths available 4in-32in
Mounting	SAE 5 hole mounting pattern
Material	316 stainless steel construction
Float diameter	1.38in (35mm) - drilling diameter 1.50in (38mm)
Warranty	1 year limited warranty with lifetime technical support

Our Verdict

The 100TECH Fuel Sending Unit is a practical, value oriented replacement for arm type senders where reliability and rugged construction matter. Its reed switch core and 316 stainless body make it a sensible choice for boats and vehicles that use the 240-33 ohm gauge standard, provided you choose the correct length and allow clearance from the tank bottom.

Frequently Asked Questions

Will this work with my existing 240-33 ohm gauge?
Yes, the sender outputs the American standard 240-33 ohm range and is designed to interface directly with compatible gauges.

How do I select the correct length?
Measure from the top of your tank to the bottom on the outside and subtract 1in; choose the sender length that is at least 1in shorter than that measurement to avoid bottom contact.

What is included for installation?
The unit ships with a gasket, mounting screws and illustrated wiring instructions to simplify fitting and connection.