This is a awesome test because it can be done very fast using a very inexpensive tool called a Noid light. This test will tell you if the computer is pulsing the fuel injectors open when cranking the engine over. Most of the time this test is done when the engine is cranking over but not starting.
However, you can do this test when the engine is running to see if a certain fuel injector is getting a signal to fire if the engine seems to be misfire for some reason.
Below is a picture of my Noid light set. Again, you can do this test within about 10 minutes provided that the fuel injectors are easy to gain access to. This test is fast, easy, safe and I have found it to be very reliable.
Here is a picture showing the noid light plugged into the injector connector when checking injector pulse a Ford Taurus.
This one came in on the hook tow truck and was a crank no start. When cranking it over, the engine had spark, the Noid light was blinking but it the engine did not did not have fuel pressure.
Engine Will Not Start – But Fuel Pump, Spark And Compression Are Good
I installed a new fuel pump to get it up and up and running. The Noid light was a big help in diagnosing the crank no start condition. Here I am checking injector pulse a Chevy truck. This particular truck would start and run just fine at first, but would not start back up after turning it off and letting the engine sit for about 20 minutes hot soak. During this time when it would not start back up, it would lose injector pulse and spark. We replaced the distributor and the ignition control module and it was good to go!
If still no injector pulse, then the computer is not pulsing the injectors open for some reason and more testing will be needed. This is a good signal. Here is a picture of the Noid light I use most of the time. Here is a quick video on how to check fuel injector pulse using a Noid light.
Here are some quick tips on how to use Noid lights.Fuel injectors can cause a whole host of problems that can lead to major engine damage if not diagnosed and replaced or repaired as soon as possible. To diagnose a fuel injector problem you need a keen sense of your vehicle, a little time and some basic fuel injector knowledge.
Learn about the possible problems fuel injectors can cause. A dirty fuel injector can cause fuel line problems such as misfiring, hard starting, stalling and hesitation. If you are experiencing any of these symptoms, the fuel injectors may be causing the problems. Listen for the problems mentioned above and for other possible problems. If there are other sounds, like clanging or high idling, the problem may be something other than the fuel injector.
Stick to the obvious symptoms in Step 1 to diagnose a fuel injector problem. Check for the engine to crank. If it cranks but does not start, the likely problem can be narrowed down to the fuel pump, wiring circuit or pump relay. Bad injector relays could also be the cause. Check to see if the fuel pump runs when cranked; if so, the problem lies in the injectors themselves.
Engine Misfiring – What Can Cause It – Tracking Down The Problem
Clean the fuel injectors and examine them for excessive wear and damage. It is important to keep fuel injectors working properly.
If you do, they will last you an incredible long time. This article was written by the It Still Runs team, copy edited and fact checked through a multi-point auditing system, in efforts to ensure our readers only receive the best information. To submit your questions or ideas, or to simply learn more about It Still Runs, contact us. Step 1 Learn about the possible problems fuel injectors can cause.
Step 2 Listen for the problems mentioned above and for other possible problems. Step 3 Check for the engine to crank. Tip Before using testing equipment on the fuel injection system, relieve the fuel pressure by disconnecting the vacuum hose from the fuel pressure regulator and removing the fuel tank cap.
About the Author This article was written by the It Still Runs team, copy edited and fact checked through a multi-point auditing system, in efforts to ensure our readers only receive the best information.Fuel injectors are connected to pressurized fuel lines.
The fuel injector controls the injection of fuel into the combustion chamber through an electronic pulse. The incoming electricity charges a solenoid that briefly opens a valve. When the valve is open, the pressurized fuel passes through the fuel injector into the combustion chamber. A single charge of the solenoid and the subsequent opening and closing of the valve is what is considered the "pulsing" of the fuel injector.
Electrical failure, electrical shorts and bad fuel injectors may all result in pulse failure. Disconnect the electrical plug from the non-pulsing fuel injector. Pull the electrical plug and wired lead away from the fuel injector to allow access to the metal tabs in the plug. Touch the red and black multimeter leads to each side of the electrical plug. You can place either lead on either side of the plug. Measure the voltage being passed through the lead. The multimeter should display approximately 12 volts.
If the lead is not producing the correct voltage, and the other leads are producing correct voltage, replace the electrical lead.
Inspect the metal connections on both the electrical plug and the fuel injector. The electrical plug and fuel injector terminal should both be free of corrosion and moisture.
Touch the tip of a screwdriver to the fuel injector. Press your ear to the handle of the screwdriver. Listen for a clicking sound through the screwdriver. The solenoid and valve operation will create an audible click that can be heard through the screwdriver when the fuel injector is pulsing. On some fuel injectors, you can feel the clicking as soon as you touch the screwdriver to the injector. Set the multimeter to measure volts. Connect the black multimeter lead to the vehicle battery positive terminal.
Connect the red multimeter lead to the electrical plug of one of the fuel injector leads. Connect one of the other electrical plugs to the respective fuel injector and repeat Steps Three and Four. You will only test the original lead. This test helps you determine what fuel injector is creating a short circuit. Continue connecting fuel injectors and retesting the original lead until all fuel injectors are tested.
A short circuit will cause non-alternation of current on the fuel injector system. Lack of current pulsing results in non-pulse of the injectors. To test the final fuel injector, connect it and pull a prior connected electrical plug.
Repeat the voltage test on the newly disconnected plug to confirm the final injector is not short-circuiting the injection system. Connect the red and black multimeter leads to each side of the terminal end of the fuel injector. Either colored lead can be connected to either side of the terminal. Compare all the resistance measurements. All of the ohms measurements should be roughly the same.
Any fuel injector with a significantly higher or lower resistance measurement is failing or has failed.I have a ultra classic with ABS. It is not starting. The battery voltage is When I turn the main switch on, I get a drop to The self test goes out and hit the start switch with nothing — no volt drop, no starter engage, no nothing.
I check the voltage at the kill switch and get But, I only get 9. All the fuses are good and there are 12 volts to the starter and the solenoid.
I have tried new system relay and start relay. Note from the guys:. Michael, you are definitely approaching this the right way. That black wire with the red tracer should be sending 12v to the starter relay. Be sure that this wire is not damaged or pinched anywhere in its travel.
You can check the start switch directly. See what the outcome is.
Harley Started to Misfire
If you can start the bike this way; the start switch is probably bad, or a wire may be damaged. You are not going to believe this — but — it was the battery in the key fob.
The bike has to have a signal from the key fob before it will allow the bike to start. I asked the dealer is they could test the ECM and they said yes if it on the bike. My key fob battery is three years old — changed them and the bike now starts.
The key fob battery is only a 3V system. I checked the battery voltage on the old battery just to see what it was — 2. And that was not enough to send a signal. Click here to cancel reply. Hi, Ken. CHECK: proper voltage to the coil. Condition of plug wires. Condition of battery. If you only have spark on the front cylinder, swap plug wires front to rear, rear to front. Now see if you only have spark on the rear cylinder.
If you do not have power to the coil; Use a small jumper wire and power your coil directly from the battery. This will will bypass your harness and switches. If you have a Tachometer, disconnect it. A bad tach can interrupt proper coil function.Having a faulty injector can cause one of your cylinders to not ignite fully, which will throw the balance of the engine off at all speeds.
This ruins fuel economy since all of the fuel may not be combusting, and you have to press harder on the gas pedal to get the car to move. Fuel injectors are a particular type of solenoid that are made to actuate their pistons very quickly. This allows the injector to deliver precise amounts of fuel into the cylinder, even while the engine is spinning at higher RPMs.
Over the life of the car, the injectors fire millions of times and eventually can wear out or clog up, preventing the engine from operating correctly. It is possible for the injector to cause issues even if it is receiving the correct voltage. They can clog up, which will decrease the spray inside the cylinder. This, in turn, causes the fuel to not burn completely and will create a misfire.
Note : Some engines have plastic panels that need to be removed before you can access the injectors. They are typically secured by bolts and can be removed with a basic socket set including an extension.
Step 2: Remove injector wiring harness. There may be a slide lock that you need to move before you can press down on the tabs to remove the wiring harness. Set the multimeter to measure ohms. Place the meter leads on the prongs inside the connector, making sure that they are not touching each other. High impedance injectors are the most common found on cars these days.
They will range from 12 to 17 ohms. Low impedance injectors are found on high performance and larger injectors. They have much lower resistance, typically around ohms. Step 5: Repeat with all injectors. They should all have a resistance within half of an ohm from each other. Any major difference and that injector should be inspected to make sure that it is firing correctly.
Step 1: Turn the car on. Turn the key to the second ON position for this test. Step 4: Place positive lead on the wiring harness terminal. The wiring harness will have two terminals that the prongs on the injector insert into.NO START,NO INJECTOR PULSE Thanks Paul jardinst21.online
Step 5: Repeat with all injector wiring harnesses. Leave the ground lead in position and test all of your injector wiring harnesses. They should all be around 12 volts. A lower reading means there is excess resistance in the wire somewhere. Hopefully, these tests have allowed you to find the issue with your fuel injectors; but, as mentioned before, it may not be an electrical problem that is causing the injector to malfunction.
The next step if the injector resistance is normal would be to remove the injector and test the spray pattern it produces on an injector tester. If you are experiencing any difficulty with testing your injectors, our certified technicians here at YourMechanic would be able to assist you with diagnosing the problem and replacing any bad fuel injectors. The most popular service booked by readers of this article is Fuel Injector Replacement.
Our certified mobile mechanics make house calls in over 2, U. Fast, free online quotes for your car repair. Schedule Fuel Injector Replacement. Service Area. Average rating from customers who received a Fuel Injector Replacement. Step 1: Make sure the key is off. Part 2 of 2: Testing injector wiring Step 1: Turn the car on.For example, hot air contains less oxygen than cool air.
The ECM uses the inputs from this sensor to help calculate how much oxygen exists in a quantity of air. ET — Engine Temperature — This sensor provides input signals to the ECM as it reacts to the engine temperature of the front cylinder head. The ECM uses the signals from this sensor to determine if the engine is at operating temperature, or still warming up. It is at the rear end of the throttle blade. It is used mostly to assist the control of idle speed.
If the ECM gets this signal for more than one second it assumes that the bike fell over and it will immediately shut down both fuel and ignition. Ion Sensing System — This system uses ion-sensing technology to detect detonation or engine misfire in either the front or rear cylinder by monitoring the electrical energy at the spark plug after every timed spark.
If an abnormal level of energy is detected across 2 or 3 spark firings the ECM responds by retarding spark timing in that cylinder as needed to eliminate it. Fuel Injectors — The fuel injectors are nothing more than electric valves that open and close to deliver a high-pressure spray of fuel pointed directly at the intake valve. They are controlled by output signals from the ECM to open at a precise moment.
If more fuel is needed, the ECM will signal the injector to remain open longer. Electric Fuel Pump — A volthigh-pressure fuel pump, located in the fuel tank supplies fuel under pressure to the fuel rail on the intake manifold. The fuel injectors will always have pressurized fuel ready and waiting for the ECM command to open. Fuel Pressure Regulator — Alsolocated in the fuel tank, the regulator controls fuel pressure between 55 and 62 PSI by returning excess fuel from the fuel pump back to the fuel tank.
The return is also located in the tank, hence only one line supply coming out of the tank. Throttle closed The more steps, the greater the amount of air enters the engine through the IAC passages. And all you carburetor guys try to keep up will ya? And, like our own brain, it has memories and it makes decisions. The first thing you hear is the in-tank fuel pump pressurizing the fuel rail. Even if you are real fast, the ECU already knows everything it needs to know from all of the sensors.
You hit the starter button, the motor begins to crank over. Throttle body blade is closed. This table eventually decays to nothing, as the motor comes up to full operating temperature. It should be noted that changes to incorporate closed-loop operation under certain operating conditions is a recent addition but the system operates virtually the same.
Open Loop — The ECM monitors sensors positioned on the intake side of the engine and does not monitor the end result of internal combustion at the exhaust. In closed loop the ECM controls the fuel mixture based on inputs from the O2 sensors.
Closed loop operation was introduced with the Dyna model and all other models in Sequential Port Fuel Injection — Injector nozzles are positioned in the manifold near the intake valve and are precisely timed to deliver fuel to each cylinder.
Still with me? The ECM also uses these inputs to determine what stroke the engine is in so it can deliver the fuel and spark at the desired time. Intake manifold pressure reflects changes in engine speed and load. Ambient barometric pressure reflects changes in atmospheric pressure caused by weather conditions or changes in altitude.
The ECM uses the inputs from this sensor to help calculate how much air is entering the engine. Great stuff!After a short ride, we stopped for her to get gas. On the way home, her Harley started to misfire and run poorly. I lost sight of her so I pulled over. After about 15 mins she showed up and said her bike would not stay running. At each stop, it would stall but would always start after the fact. It died in the driveway. We tried to troubleshoot the problem but have been unsuccessful so far.
Checked the fuel pump, getting gas, changed the plugs and checked the wires for leaks, no leaks. We then changed the coil with no success. The bike would start at high idle and then slow to a stall.
We fixed the wire at the coil, and tried to start the bike again with the same result. I then did another code check and at P I got a blank screen and then a no rSP- no response?
As you can see, I need help. My wife is a ride-aholoic and I have to live with her and 1 running motorcycle. It gets embarrassing riding on the back of your own motorcycle to keep peace in the house. Note from the guys:. If you were chasing a fuel problem you would want to see what you have for, running fuel pressure.
Fuel Injector Symptoms
However, this problem sounds much more like a failing sensor. If you can not pick up any relevant codes on your own, you may need to submit to having a dealer plug in their scanalizer. If it takes them an hour labor time to come up with a definitive diagnosis, it may save you a lot of aggravation.
Click here to cancel reply. Problem was a dirty air filter. Tip: do not oil the filter. Thank you David. Should any ground have twelve volts.