"Fun With The Tank Pump Fuse"

The Tank Pump Fuse can be very helpful — if you have a 200 series Volvo, and a Test Light or Digital Multimeter.

Depending on the Fuel Injection system, the Tank Pump Fuse will be or #4 (LH 2.2, 2.4) or #5 (K-jet, LH 2.0, LH 1.0)

When looking at the fuses, the unfused or "Hot" side is on the left, as shown below.

Hot (+) side —*—<<—(FUSE 4/5)—>>— fused (–) side goes——> to the Tank Pump

* Voltage at (or applied to) the Hot side goes *DIRECTLY* to the Main Pump. (This point SHOULD normally be at +12V whenever the FI Relay is energized.)

At the Fuse Holder, you can:

• Verify Fuel Injection (aka Fuel Pump) Relay operation. (Look for +12V on Fuse 4/5 input while cranking)
>>>• Test ("hot wire") either Fuel Pump (or both) Get +12V from fuse 6 input contact <<<
• Use the hot wire as a No-Start diagnostic, or to run pumps for pressure tests, etc.
• Measure each pump's Current "draw" (requires Ammeter function, 10 amps max is OK)
• Test and measure the O2 heater resistance (LH 2.4)

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Bruce Young
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.