Question about 1994 Isuzu Pickup

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My 94 isuzu pickup has park but no injector pulse and I have also noticed my check engine light is not coming on when key is on

My 94 3.1l pickup will not start.I have spark no pulse,but 12 volts on all four wires to the injectors.I have also noticed that my chek ingine light is not coming on when I try to start the truck,also not hearing the fuel pump ome on

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6ya6ya
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Posted on Jan 02, 2017

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freetek
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SOURCE: no pulse at injectors

The normal way that injectors are controlled is via the permanent application (ignition on obviously) to one side of the coil that operates the enclosed piston, and the precisely timed application of ground (negative) to the other side of the coil. The transistors that control this switching under the command of the engine computer are typically contained within the computer itself. Measuring the voltage at the injectors is not productive since the common multimeter is incapable of detecting the very short pulses that activate the coil. Some kind of visual means would be needed to observe this pulse such as an oscilloscope or an engine analyzer equipped with a 'scope.
It's unlikely that all of the switching transistors (or the injectors) have failed simultaneously so either the computer has a problem or there is no fuel being delivered to the fuel rail that feeds the injectors. You should find a pressure regulator that sits between the fuel line coming from the tank that controls the fuel pressure for the injectors. This device seem to be a sore point in many vehicles and can make it appear that the injectors are not working. Many fuel rails have a fitting similar to a tire valve to allow the testing of the pressure being delivered. I would recommend you check this before assuming that the injectors are at fault.  

Posted on Nov 14, 2008

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SOURCE: 1989 Isuzu Trooper Won't Start

Oil level!!!

Posted on Feb 16, 2009

honeymokey
  • 3113 Answers

SOURCE: 2004 Isuzu Rodeo 3.5ltr 4X4 hesitation/misfire acceleration

The upper intake gaskets may be leaking. They are made of plastic and metal and will leak air. Do not remove the cover on very top of manifold when changing.

Posted on Jul 24, 2009

  • 102 Answers

SOURCE: Isuzu Hombre pickup, 2.2L Vortec, Won't Start.

You need four things for an engine to run. 1. fuel 2. spark 3. compression 4. timing (spark at the right time. By your post it seems you have fuel and spark and you probably have compression unless you blew a head gasket. That leaves the timing. Check the timing and/or the timing belt or chain whichever you have.

Posted on Aug 07, 2009

  • 172 Answers

SOURCE: electrical problem is keeping throttle body from working

The injector needs a signal to open.

Posted on Aug 12, 2009

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94 Opel kadett 1.6 single injector. Petrol does not seem to get thru for car to start.petrol pump is ok.where could the problem be.


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.

Sep 13, 2014 | Cars & Trucks

1 Answer

Starts cold but not when warm


Are you certain that the pump is on when the no start occurs? Do you hear it turn on with key on, not start, when the engine won't fire? It should turn on for 2 seconds to pressurize the line to the injectors. If you could, check fuel pressure when the no start occurs.

If it is the injectors, buy a cheap "noid light" to check the injector circuit. Buy the one that fits your injector harness connectors. You pull off a connector to one injector and put the noid light in the connector. When cranking the engine over the noid light should be blinking-that is the pulse that fires the injectors. The injectors have battery voltage to them any time the key is on. When the ecm momentarily grounds the injector circuit (internally in the ecm), the injector is pulsed. If the noid light does not blink or even light up when cranking, the injector circuit has a problem in the power side or the ground side.

Feb 09, 2014 | 1991 Chevrolet C/K 2500

1 Answer

Fuel injectors not spray


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.

Jan 28, 2014 | Isuzu Cars & Trucks

1 Answer

Engine light does not come on 1994 isuzu pickup


Should come on during self check,if the rest of the lights come on(oil pressure,temp. ect.) the bulb must be bad.
I recall something with GM years ago about the filliment in the check eng light having to be intact.
Battery terminal connections are critical,make sure everything is clean and tight
Plus make sure the chassis ground from the battery (smaller black wire should be with the big black battery cable) is a good connection to ground on the BODY
Hope there's some help in the somewhere,good luck.

Feb 27, 2012 | 1994 Isuzu Pickup

1 Answer

I have a 1996 chevy pickup that won't start. Fuel


Have you sprayed fuel/starting fluid into the engine to see if it starts? You can have fuel pressure but no injector fuel delivery, we call this "pulse"

Feb 07, 2012 | 1996 Chevrolet K1500

1 Answer

Buick lesabre 94,crank but wont start,got spark but not open fuel injectors


Check your fuses. Check at an injector plug for power with the key on. One wire would be power with the key on. The other wire would be a ground pulse when the engine is turning (running or starting). Both wires may show hot but it could just be power feeding back. If you have a test light capable of testing for ground, check for ground as well while the engine is cranking (a noid light is ideal).
If no ground or you cannot test for it, take the ignition module to an autozone so they can test it for free.

Aug 25, 2011 | 1994 Buick LeSabre

2 Answers

94 buick park avenue ,one injector connector is not working


NO THIS IS NOT A COMMON PROBLEM...YOUR MAIN PCM... POWERTRAIN CONTROL MODULE ( COMPUTER ) IS THE ONLY DEVICE THAT GROUNDS THE INJECTORS ONE AT A TIME.. INSIDE THE PCM ARE TRANSISTORS THAT MOUNT TO HEAT SINKS ON SIDE....FIRST THING IS TO OHM OUT WIRING HARNESS FROM INJECTOR PLUG TO PCM... .. IF GOOD THEN PCM TIME I HAVE ONLY SEEN THIS PROBLEM ONE TIME....

Oct 11, 2009 | 1994 Buick Park Avenue

1 Answer

1990 K5 Blazer DIED(Electrical?)?


There may be no injector pulse if the computor does not see a RPM signal.
There will be no spark if the ignition module does not see a dist pulse from the dist pickup.......a RPM signal.
Because you do not have both ......I would suggest to check/change the dist pick up.
Follow the wires from the ignition module inside the dist to the pickup which is also inside the dist.
If it is just a bad dist pickup....keep all your old parts as good spares.
Also...is the dist turning? to provide a RPM signal?
You will have to remove the dist to change the pick-up.....mark your timing locations......"rotor position" and "dist body location"before removal.
A quick test before installing the "repaired dist" .....plug it in the the truck wiring and turn on the key....DO NOT CRANK THE ENGINE OR YOU WILL LOSE YOUR DIST ROTOR CORRECT POSITION......as you spin the dist by hand .....the injectors should spray.

Aug 23, 2009 | 1989 Chevrolet S-10 Blazer

1 Answer

2004 Isuzu Rodeo 3.5ltr 4X4 hesitation/misfire acceleration


The upper intake gaskets may be leaking. They are made of plastic and metal and will leak air. Do not remove the cover on very top of manifold when changing.

Jul 24, 2009 | Isuzu Rodeo Cars & Trucks

2 Answers

No pulse at injectors


The normal way that injectors are controlled is via the permanent application (ignition on obviously) to one side of the coil that operates the enclosed piston, and the precisely timed application of ground (negative) to the other side of the coil. The transistors that control this switching under the command of the engine computer are typically contained within the computer itself. Measuring the voltage at the injectors is not productive since the common multimeter is incapable of detecting the very short pulses that activate the coil. Some kind of visual means would be needed to observe this pulse such as an oscilloscope or an engine analyzer equipped with a 'scope.
It's unlikely that all of the switching transistors (or the injectors) have failed simultaneously so either the computer has a problem or there is no fuel being delivered to the fuel rail that feeds the injectors. You should find a pressure regulator that sits between the fuel line coming from the tank that controls the fuel pressure for the injectors. This device seem to be a sore point in many vehicles and can make it appear that the injectors are not working. Many fuel rails have a fitting similar to a tire valve to allow the testing of the pressure being delivered. I would recommend you check this before assuming that the injectors are at fault.  

Sep 08, 2008 | 1994 Isuzu Rodeo

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