How to test injectors - VN 1500 Vulcan Drifter kawasaki Motorcycles

If plug an plug wire has been replaced , an dist. cap an rotor an problem is still there ,maybe a fuel injector problem .
Perform the fuel injector coil test. Refer to Fuel Injector Solenoid Coil Test .
A fuel injector coil winding resistance that is too high or too low will affect engine drivability. A fuel injector control circuit DTC may not set, but a misfire may be apparent. The fuel injector coil windings are affected by temperature. The resistance of the fuel injector coil windings will increase as the temperature of the fuel injector increases.
Diagnostic Aids
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Monitoring the misfire current counters, or misfire graph, may help to isolate the fuel injector that is causing the condition.

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Operating the vehicle over a wide temperature range may help isolate the fuel injector that is causing the condition.

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Perform the fuel injector coil test within the conditions of the customer's concern. A fuel injector condition may only be apparent at a certain temperature, or under certain conditions.

2

Observe the ECT Sensor parameter with a scan tool.
Is the ECT Sensor parameter within the specified range?
10-32?°C (50-90?°F)
Go to Step 3
Go to Step 4

3

1. Disconnect the multi-way harness connector of the fuel injectors.
2. Measure the resistance of each fuel injector between the ignition 1 circuit and the fuel injector control circuit, at the multi-way connector with a DMM. Refer to Testing for Continuity in Wiring Systems.

Is the resistance within the specified range for each injector?
11-14 ohms
Go to Fuel Injector Balance Test with Special Tool or Fuel Injector Balance Test with Tech 2
Go to Step 6

4

1. Disconnect the multi-way harness connector of the fuel injectors.
2. Measure the resistance of each fuel injector between the ignition 1 voltage circuit and the fuel injector control circuit, at the multi-way connector with a DMM. Refer to Testing for Continuity in Wiring Systems.
3. Record each fuel injector resistance value.
4. Subtract the lowest resistance value from the highest resistance value.

Is the difference equal to, or less than, the specified value?
3 ohms
Go to Fuel Injector Balance Test with Special Tool or Fuel Injector Balance Test with Tech 2
Go to Step 5

Check the injector circuit. Here's how injectors usually work: when key is on, they have live power available to them. Key on, the circuit is turned on, so power passes through a fuse to the injector on the power wire. (Check the fuse- it's under the hood, most likely.)
To make the injector "pulse" or spray fuel out, the engine computer will internally ground the circuit for a split second. The injector has a power wire to it from that fuse. Then the ground wire at the injector goes into the computer.

If you have a test light, you can test the circuit. First, clip a test light ground lead to negative battery post. With key on, and the injector connector unplugged, check for battery voltage on the power wire. One of the wires should have voltage and will light up the test light. Now, move your test light lead to the battery POSITIVE post. Have a helper be cranking the engine over while you probe the ground wire-the one that did not light up the test light. If the injector circuit ground is good, the test light will now be blinking. (You are putting voltage into the ground wire to the computer, to check if it is properly grounding the circuit. Every time the light blinks, the computer has grounded the circuit.)
If the circuit passes both tests (key on, steady test light on power wire; engine cranking, blinking light on ground wire), then the injector circuit is good. The injector should be pulsing when it is connected and the engine is cranking. If no gas is coming out of the injector, could be that fuel is blocked somewhere (filter?) from reaching the injector, or it could be a shorted injector. Someone with a volt-ohm meter should check the resistance across the injector terminals and compare with manufacturers' specifications. This will determine if the injector is bad.

You can check the injector circuit with a test light. Have you verified no fuel is coming out of bottom of injectors, when the engine is cranking over? Use a flashlight, looking down the throttle body.

Ground a test light lead to a good ground. Pull injector connectors off, and turn key to on The white wire with red stripe is the power wire to both injectors, it is hot anytime key is on. The wire splices off to both injectors. If power is good, check the ground side of circuit: place the test light clip on the POSITIVE post of battery, and put probe into the ground terminal of the injector connector-the black wire. Now have someone cranking the engine over-the test light should be blinking. Every time it blinks, the computer is repeatedly grounding the injector circuit (internally) and this causes the injector "pulse"- turning the injector on for fuel to spray out. If both tests are good (power with key on, and blinking ground with engine cranking) the injector circuit is working as it should. If no power, check computer for power in-check the main relay, for one.
As for the injectors themselves, not likely both would go out at same time, but only way to test them on the vehicle is to put an ohm meter across the terminals and check resistance. Both should be similar, with low ohms showing, somewhere on the order of 2- 10 ohms, I don't know the specs for Nissan-check with the dealer.
Good luck, let me know what you find out.
To verify the injectors or the injector circuit is the problem, try a little starting fluid down the throttle body, or even carburetor cleaner. If the engine fires and runs a few seconds, then you know injectors or circuit is the problem.

Are you sure it's not the fuel pump? I would be checking fuel pressure-the injectors need fuel under high pressure against them so they will spray out when pulsed.
What year is your Isuzu, and what size engine? Multiport injection has a higher pressure requirement than throttle body injection.
There should be a fuse for the injectors, check that. With key on, not start, the injectors would have power to them on the "injector drive circuit". In other words, constant power is supplied to the injectors when the key is on. The other wire at an injector is the ground wire. The ground wire goes into the engine computer. When the computer internally grounds the injector wire for a split second, the injector is energized and fuel is able to spray out.
Post back if you need help checking the injector circuit-both the power side and the ground side. You can check both with a test light.

Well, here it is anyway: ground a test light and probe the injector connector. With key on, one terminal should be hot-the drive circuit. Now move the test light lead to the POSITIVE battery post, and stick the test light probe into the injector terminal that did not light the test light-the ground terminal. Now have someone crank the engine over. If ground circuit is working, the test light should be blinking-meaning the computer is properly grounding the injector circuit. If both tests are good-a steady light on the power side (key on) and a blinking light on the ground side (engine cranking), the injector circuit is good.

What test told you it is not firing?

You may have valve damage &
little compression

Check for a fuse for the injectors in the power distribution box by the battery. Parts stores sell a cheap little tester called a "noid light" for testing injector circuits. They come in several sizes, so get the one that fits your injector connector. To use it, you pull off one injector connector and plug in the test light. If the circuit is good, the light will be blinking when the car is cranked over. If you get nothing, pull off all the injector connectors and test again. If you have one shorted injector, it may have shut down your injector drive circuit- that's why to pull off all connectors and re-test.
Here's a brief on how the injector circuit works: When key is on. the injectors will have constant battery voltage available to them on the power side (the injector drive circuit). When the engine is cranking or running, the engine computer will momentarily ground the ground circuit of injector (the ground wire goes straight into the computer for internal grounding), causing the injector to pulse. If you have no pulsing, determine if it is the drive circuit (no power to injectors), or the ground circuit that has failed.

I wouldn't think CPS if you are getting a good blue healthy spark.
Check your injector circuit with a test light: Pull off one injector connector, ground the test light, and probe the injector connector with key ON. If your injector drive circuit is working, one of the terminals on the injector connector should have a steady light. Now check the injector ground circuit: move the test light lead to the positive battery post, and probe the injector terminal that did not light the test light, while someone cranks the car over. If ground is working, you should have a blinking light, meaning the computer is properly groundind the injector to pulse. If both tests are good, the injector circuit is working properly. The drive circuit is routed through the ignition switch, and the ground circuit goes into the computer.

there are a few things that can be tested on the fuel injectors, 1st you need to unplug each injector and test the resistance on each injector, you do this with a DVOM the resistance across the the injector windings should be 8.0-25.0 ohms, if the injectors ohm out ok then remove the fuel rail with all the injectors attached and set all the injectors in a catch container ( baby food jars work real well for this ) and crank the engine and make sure each injector is spraying a good clean patten with no dipping. replace any injector that is out of range on ohms and any that do not have a good clean spray pattern.

FUEL INJECTOR NOT FIRING COULD BE FAULTY FUEL INJECTOR.HOOK A NOID TEST LIGHT TO FUEL INJECTOR ELECTRICAL CONNECTOR. CRANK THE ENGINE WATCH THE NOID TEST LIGHT SHOULD BE BLINKING WHILE ENGINE TURN OVER.IF TEST NOID LIGHT STEADY PCM FAULTY NOT FIRING THE FUEL INJECTOR.IF FUEL INJECTOR DONT BLINK OR LIGHT UP.YOU HAVE OPEN WIRING CIRCUIT TO THE FUEL INJECTOR CONNECTOR.

Test fuel injector pulse and supply voltage output (test is used for most cars). This test will tell you if the computer system has operating voltage and injector trigger signal. Remove an electrical connector from a fuel injector (it doesn't matter which injector) probe both sides of the connector with a grounded test light
(there are only two terminals). Have a helper turn the key to the "on" position without cranking the engine and observe the test light. The test light should illuminate one side of the connector only. Next, switch the test light lead to the positive side of the battery to test the system ground injector trigger, probe the side of the connector that did not light up, have a helper crank the engine over and observe the test light, it should blink on and off. If this test checks ok continue to next step. (Note: if no injector pulse is present try disconnecting the remainder of injectors and re-test, if a fuel injector is shorted it can shut down the injector driver causing no injector pulse. If injector pulse returns plug injectors electrical connectors in one at a time until the pulse fails and replace that injector)

If this test revealed that there was no pulse but system has power the ECM is not generating a fuel injector trigger. If there is no trigger to the fuel injector it will not allow fuel to enter into the engine. Some of the most popular reasons that can cause this condition include a shorted crankshaft angle sensor, shorted camshaft position sensor or shorted ECM/PCM. (When a system trouble code scan is performed it does not always catch a crankshaft angle sensor, camshaft position sensor failure). Tip: try disconnecting all non-essential sensors, example: oxygen sensor, coolant sensor, throttle position sensor, air intake temperature sensor, mass air flow or map sensor and EGR valve pressure differential sensor. Crank the engine over, if the injector pulse returns, one of the sensors is shorted causing the system to not operate. Plug the sensors in one at a time until the injector pulse fails then replace that sensor and reassemble.

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http://www.2carpros.com/first_things/car_cranks_but_wont_start.htm

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