NO. Guhl Motors does not modify any ECU of a vehicle that has a VIN number, has had a VIN number, or any vehicle that is or can be street driven. This includes ALL motorcycles.

You can contact us simply by giving us a call during our usual business hours at 717-618-4212 or filling out the contact form. You can find that here!

Our business address is 102 South State St, Ephrata, PA 17522.

We are open Monday-Thursday from 9-5:30. On Fridays we are open from 9-12. We are closed on weekends.

Please include your name, address, phone number, and email, along with a description of what you’d like us to do with what you’ve shipped.

We are currently working on an online store for your convenience, at this time we are taking orders over the phone.

Yes, we ship internationally. Customer is responsible for all duties and taxes.


Generally, no. Injectors rarely fail. They normally get debris in them, which causes them to either stick closed, stick open, or reduce the flow. This can generally be fixed by back-flushing the injector while continuously energizing and deenergizing the injector.

YES!!! It is imperative that you get your injection cleaned if an engine failure occurs. Often times, when an engine fails, engine schrapnel will make its way up into the airbox. If this is not cleaned out, as soon as the new engine is started, that debris will be ingested by the new engine, causing another immediate failure. It is highly recommended that the air filter be discarded and replaced as well.

All the wires going to all the connectors should be thoroughly inspected. Systems with moving velocity stacks should be taken apart to verify that the velocity stacks haven’t been dislodged.


Pros of custom braided harness:

  • All-new wires, terminals, and connectors
  • Higher quality wire with better insulation
  • Fuel pump and fan relays already integrated
  • Pre-wired data acquisition connector
  • Pre-wired MorDefy connector
  • All connectors are labeled for simplified installation
  • All harnesses are 100% tested during manufacturing, including pin-out, resistance, and hi-pot testing
  • Made by a professional wire harness manufacturer with state-of-the-art automated equipment
  • All splices are ultrasonically welded for the most reliable operation

Pros of tape harness:

  • Cheaper
  • Easier to repair

Probably. Generally, when you crash, there are a lot of G-forces exerted on all of the components, and the wire harness often takes the brunt of the load. It is common for wires and terminals to get ripped out of connectors. Simple repairs for the harness are feasible, but often times for harnesses with a lot of damage, it makes more sense to replace them completely. 


The Mychron system is well-suited for general data acquisition, but is limited in its ability to interface with most stock ECUs. It can do things like track-mapping and lap times, which the WiDefy cannot do. 

The WiDefy system is integrated with the ECU to read all sensor data from the ECU, as read by the ECU. The data analysis software and the tuning software are combined to form a seamless tuning environment. The WiDefy is designed to be connected to an after-market dashboard to display all pertinent information, so no additional gauges are needed. It is a cloud-based system that allows for easy remote tuning from your favorite tuner, no matter the location.


The primary filter (the one between the tank and the pump) keeps the fuel pump inlet screen from getting plugged up, which causes the fuel pump to fail. The secondary fuel filter protects the injectors from debris that comes from the fuel pump. This one is a critical filter and should come from Guhl Motors.

If your engine has spark on all four cylinders, the problem is not the cam or crank signal, and is likely not power or ground related. The next step would be to do the “cardboard test” (see next FAQ).

To do this test, first loosen the intake boot clamps and lift the injection up off of the motor, leaving everything else connected. Insert a piece of cardboard between the throttle-body and the engine. Next, turn the fuel pump on, and after 30 seconds turn it back off and remove the cardboard. There should be no wet spots indicating fuel leaking from the injectors. If there is a wet spot, proceed to clear debris from the injectors.

If there are no wet spots, reinsert the cardboard between the throttle-bodies and the engine, turn on the fuel pump and the ignition switch, and crank the engine over for roughly 30 seconds. Then, remove the cardboard again, and there should be 4 evenly-sized wet spots, indicating normal injector operation. If there are no wet spots, the injectors don’t have power, or all four injectors are stuck closed (this is a common occurrence for injectors that have sat for a couple months). Unevenly sized wet spots would indicate that there is debris in the injectors.

Ask Tech Questions

We would love to answer some of your tech-related questions and put them in the FAQ page of our website for future customers to benefit from.

FAQ Form