Frequently Asked Questions About Peterbilt 359 Fuel Tank Senders

Will these fuel tank senders fit my specific year Peterbilt 359?

Our fuel tank senders are designed to fit Peterbilt 359 models from 1967 through 1987. However, there are variations depending on your tank configuration. Single tank setups use one sender unit, while dual tank systems require two senders. Most senders feature standard SAE 5-hole mounting patterns, but we recommend verifying your tank's mounting hole spacing before ordering. If you're unsure about compatibility, contact us with your VIN and we'll help identify the correct sender for your truck.

What's the difference between mechanical and electrical fuel senders, and which do I need?

Mechanical senders use a float arm connected directly to your dash gauge through a cable, while electrical senders use a variable resistor to send signals to an electric gauge. Most Peterbilt 359s came with electrical senders that operate on a 33-240 ohm range. To determine which type you need, check if your fuel gauge has electrical connections or a mechanical cable. Electrical senders are more common and generally more reliable, but you must match the ohm range to your existing gauge for accurate readings.

How difficult is it to install a fuel tank sender, and what tools do I need?

Installation typically takes 1-2 hours per tank and requires basic hand tools. You'll need a socket set, screwdrivers, and potentially a spanner wrench for the locking ring. The main challenge is safely draining the fuel tank first - we recommend having less than 1/4 tank before starting. Common issues include corroded mounting screws and damaged gaskets, so have penetrating oil and a new gasket ready. Always disconnect the battery before beginning electrical connections to prevent sparks near fuel vapors.

Why is my new fuel sender giving inaccurate readings?

The most common cause is incorrect float arm adjustment. The arm must be bent to match your specific tank depth - measure from the mounting flange to the tank bottom and adjust accordingly. Another frequent issue is mismatched ohm ranges between the sender and gauge. Ground connection problems can also cause erratic readings. Make sure the sender unit has a solid ground through the tank mounting, and check that all electrical connections are clean and tight. Some aftermarket tanks may require custom float arm lengths.

What's the typical lifespan of a fuel tank sender, and what causes them to fail?

Quality fuel tank senders typically last 5-10 years depending on use and fuel quality. Common failure points include worn resistor strips causing dead spots in gauge readings, corroded electrical connections, and float arm pivots that seize up. Ethanol-blended fuels can accelerate deterioration of older sender units. Signs of impending failure include erratic gauge readings, gauge stuck at full or empty, or readings that change dramatically while driving. Regular fuel filter changes and avoiding running tanks completely empty can extend sender life.