Fuel Injector Service

The internal tolerances inside a modern electronic fuel injector are held to 1 micron (a human hair is around 40 microns in diameter).  It doesn't take a very big "foreign object" to effect an injectors performance.  Dirt is an obvious contributor to deteriorated fuel injector performance.  Most injectors have a built-in 30 micron filter in the inlet.  If that gets plugged, flow is reduced. The truth is, though, that the vast majority of race car fuel injectors don't have plugged filters.  We don't have internally rusting steel gas tanks.  Unless your fuel cell foam is coming apart and you don't run a fuel filter after the fuel pump, your injector filters are probably OK.  We replace the filters as part of our cleaning process, but it's probably overkill. 

Much bigger problems for racing fuel injectors are long periods of storage and injector heat soak.  The problem in both situations is deposits left by the fuel trapped in the injector when the engine is shut off.  In the case of long storage, the fuel will turn to "varnish".   Everyone's experienced this with a power tool left with fuel in the carburetor over the winter that refuses to run again in the spring.  This type of deposit might be able to be cleaned with chemicals in the fuel...but maybe not.

Heat soak is a tougher problem.  Heat soak is caused when the injectors and in particular the pintle head of the injectors, are exposed to very high temperatures created by the engine. Because of the location of the injector, when the engine is switched off and the injector remains closed, a small residual amount of fuel remains on the pintle end of the injector. The heat from the engine evaporates the lighter gases and the heavier particles of the fuel settle at the tip of the injector. Engine heat then bakes the heavier particles, making them a fine layer of hard, "baked on", difficult to see and difficult to remove deposits.   This contamination can effect the travel and seating of the pintle, which can reduce the volume of fuel delivered, distort the spray pattern and alter fuel atomization.  Only ultrasonic, solvent back-flushing of pulsing injectors has been proven to remove this baked-on contamination.

The majority of  race car injectors we've tested perform adequately (not all sets are equally matched, but within specification).  That being said, many of the injectors we've tested have had some kind of problem that would reduce the engine's performance -- sometimes subtly and sometimes dramatically -- and most injectors get some flow improvement with ultrasonic cleaning.   The expense to clean and test a set of fuel injectors is insignificant compared to what is invested  in time, money and emotion to go racing.

1. Injectors are washed in mineral spirits and then externally ultrasonically cleaned to remove exterior dirt and grime.
2. Each injector is then inspected for external damage (e.g. broken pintles, corroded inlets or tips, etc.).  Injectors with external damage are removed from the process and must be replaced.
3. Each injector that has passed the inspection is then engraved with a unique serial number.
4. Each injector's impedance (resistance to AC current flow) is then measured.  Over time, the impedance of an injector can increase.  This reduces fuel flow for a given injector pulse.  Injectors with out-of-spec impedance are removed from the process and must be replaced.  We don't see this much on race car injectors.
5. All injectors are now tested for leaks, spray pattern, atomization, dynamic flow and static flow.  All data is recorded
6. The injectors have replaceable parts removed (filters, o-rings, pintle caps, etc.).
7. The injectors are placed in an ultrasonic cleaning bath and pulsed at varying rates and pulse widths for 20 minutes
8. New parts are installed on the injectors and the leak test, dynamic and static flow tests are repeated.  All data is recorded.
9. If necessary, any injectors not meeting specifications are re-cleaned and re-tested.
10. Each injector is internally treated with a corrosion inhibitor.
11. The injectors are vacuum bagged to prevent contamination and corrosion while stored.  The bags are identified with the serial numbers of the injectors and the date of service.

What You Get
Your fuel injectors are vacuum bagged and shipped back to you prepaid (insured Priority Mail).  Also included is a complete record of the test results. You can see a sample report here. 

What It Costs
$25 per injector for the first time we clean and test an injector.  Any subsequent cleaning and testing of an injector we originally serviced is $10 per injector -- for the life of the injector.  Our prices include return shipping to you via insured Priority Mail.  Expedited delivery is available at extra cost.

Next Steps
I'm still working on a new submission form, but in the interim, just give me a call at (612) 964-5830 or drop me an email to let me know you've got some injectors coming to me...or just to shoot the breeze.