Mercury OptiMax DFI 75-250 HP (Fuel Injector) Fuel Injector Cleaning & Flow Testing

The Siemens 37001 is a DFI marine (2-stroke direct injection, fuel side) fuel injector used in Mercury OptiMax DFI 2-stroke outboards, 1.5L-3.0L (75-250 HP, 1999-2010). Red side-feed fuel injector; works alongside the OptiMax air injectors.. We ultrasonic-clean and flow-test injectors like this one in our shop, then send back before-and-after data so you know exactly what you're getting.

Manufacturer	Siemens
Part number	37001
Type	DFI marine (2-stroke direct injection, fuel side)

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Our measured results

These are the actual before-and-after numbers from our flow bench for the Siemens 37001 — not published estimates.

Tested in our shop	12 injector(s) @ 50.0 psi
Measured coil (avg)	1.91 Ω
10s open flow (avg)	99.58 → 99.92 ml (+0.3%)
60s pulsed flow (avg)	91.17 → 91.08 ml
Leak test after cleaning	12/12 PASS

Also known as / cross-references

The Siemens 37001 is interchangeable with or cross-references to these part numbers:

804528 (Mercury OEM)

What vehicles use the Siemens 37001?

Mercury OptiMax DFI 2-stroke outboards, 1.5L-3.0L (75-250 HP, 1999-2010). Red side-feed fuel injector; works alongside the OptiMax air injectors.

How we service it

Every injector gets ultrasonic cleaning, backflushing, before-and-after flow testing (static and dynamic), leak testing, spray-pattern inspection, and new O-rings and micro-filter baskets where available — plus a detailed Injector Performance Report. Round-trip USPS shipping is $15 flat.

Frequently asked questions

What vehicles use the Siemens 37001 injector?

The Siemens 37001 is used in Mercury OptiMax DFI 2-stroke outboards, 1.5L-3.0L (75-250 HP, 1999-2010). Red side-feed fuel injector; works alongside the OptiMax air injectors..

Can you clean and test a 37001 injector?

Yes. We ultrasonic-clean, backflush, and flow-test the Siemens 37001 on our bench, including before-and-after open and pulsed flow, leak testing, and spray-pattern inspection, with new O-rings where available.

What did the 37001 flow at?

On our bench, 12 37001 injectors averaged 99.58 ml open flow before cleaning and 99.92 ml after, tested at 50.0 psi.

How much does it cost?

Standard MPFI top-feed injectors are $30 each; side-feed, GDI, TBI and specialty injectors are $35 each. Round-trip shipping is $15 flat, 4-injector minimum.

How do I send them in?

Start an order on our Get Started page, ship your injectors to our Weymouth, MA shop, and we return them cleaned, tested, and documented.

Send in your 37001 injectors

Mail-in cleaning and flow testing with a full before/after report. 4-injector minimum, $15 flat round-trip shipping.

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