240-33 ohms 4ft Fuel Tank Sending Unit - Durable Doughnut Float Sender

Our review of the 240-33 ohms 4' Fuel Tank Sending Unit finds it ideal for boat, RV and truck owners who need a rugged replacement sender that pairs with non-linear gauges. The standout reason to buy is durability: its doughnut float and reed-switch resistor array eliminate fragile swim-arm pivots and reduce mechanical failure points, so it tends to keep giving steady readings over time. Installation is straightforward with the included gasket and screws, and it is built for marine use with SUS 316 stainless mounting hardware.

Key Features

• Doughnut float design: Provides a compact, sealed float that resists sticking and reduces moving part failures for longer service life.
• Reed switch construction: Uses multiple reed switches and fixed resistors for a reliable non-linear signal that matches standard non-linear gauges.
• Marine-grade hardware: SAE 5-hole pattern and SUS 316 stainless steel components resist corrosion in boat and marine environments.
• Complete installation kit: Ships with gasket, mounting screws and illustrated instructions to make a typical installation take about 15 minutes.
• Versatile compatibility: Works as a fuel or water tank sender for boats, RVs, trucks and cars when paired with a compatible gauge.

Who It's For

This sender is aimed at owners of boats, campers and trucks who need a durable, corrosion-resistant replacement for a failed or missing tank level sender and who already have-or plan to install-a compatible non-linear fuel gauge. It is particularly useful where a sealed float and minimal mechanical linkages are desired due to vibration or rough conditions.

Those who should look elsewhere include owners who require a linear-output sender for a specific gauge type, or anyone whose tank depth or mounting pattern differs significantly from the SAE 5-hole layout; careful measuring of tank depth and hole diameter is required before purchase.

Pros & Cons

Pros

• Robust doughnut float and reed-switch array reduce mechanical failure risk.
• Marine-grade SUS 316 mounting hardware improves long-term corrosion resistance.
• Easy to install with included gasket, screws and clear wiring instructions.

Cons

• Non-linear output means it must be matched with a compatible non-linear gauge; not suitable for linear-only systems.
• Some users report occasional misalignment of mounting screw holes on certain tanks, requiring careful test-fit.

Specifications

Our Verdict

The 240-33 ohms 4' Fuel Tank Sending Unit is a practical, well-built replacement sender for marine and vehicle applications where a non-linear gauge is used. Its doughnut float and reed-switch construction deliver steady, low-maintenance readings and the SUS 316 hardware suits corrosive environments. It offers strong value for owners needing durability and straightforward installation, provided they confirm gauge compatibility and tank dimensions first.

Frequently Asked Questions

Will this work with my existing fuel gauge?
It will work with gauges that accept a non-linear 240-33 ohm signal; confirm your gauge type before buying.

How deep can my tank be for this sender?
The sender length should be about 1' less than tank depth for plastic tanks and 0.5' less for metal tanks to avoid hitting the bottom.

Do I need to drill a hole to install?
If your tank lacks a suitable opening, a 1-1/2' (38mm) hole is recommended for this unit.