Hi AC,
Is this 4WD?
Is this automatic?
Thanks,
Vinny
Hello Vinny:
Yes, 4WD, automatic
Hook the test light to the positive battery terminal and while cranking, check to see if you get a flashing test light to either prong at an injector plug.
Let me know what you find.
Vinny:
Test done as req'd. Test light did not flash on neither injector elec connectors while cracking the engine. Before turning ignition sw to ON position test light was ON for one each of the connectors plug, it went off at as sw was moved to crank position.
More test to do?
Tks,
I will look up the wiring circuit and get back to you on what to test next.
Thank you, I will be waiting for your advice...
I am attaching the wiring diagram below. The ignition switch provides voltage to the ECM 1 fuse that powers both injectors. (shown at the top of the diagram). Check this fuse first (it is at the bottom of the fuse box under the dash second from the left) and make sure you have voltage at both sides. This circuit is more than likely your problem because you say that you do not have voltage at the injectors and this diagram shows that you should.
Venny:
Tested as follows. All fuse checked ok with test light ON. specially ECM 1. Also while cracking I got test light ON for both sides on this ECM 1 fuse. I double checked again at the injectors elec connectors plug with test light on positive battery terminal and other end at the injectors plug (both connectors plugs) still no test light.
What can I test next?
Tks
Well it appears that the wire that goes from the ECM1 fuse to the fuel injectors is broken somewhere or maybe a plug or connector is having a problem. Follow the wiring harness starting from the injectors to where it disappears into the harness and see if you notice any connection problems.
If nothing, then you can get a 10amp inline fuse and connect it to the positive battery and connect the other side to the red and white wires that go to the injectors. This should let it start.
Let me know how you make out.
I probably misunderstood some instrucions from you, my excuses.
I just did further tests...
As I just lamp tested ok fuse ECM 1 to chassis, then with injector elec connector removed form injectors I did the same thing on wires 481(red) and 482(wht) on drawing to chassis while ignition sw was ON and then on cranking position I got lamp ON for both wires. That tells me the wires are good up to those points.
Then I measured volts on injector plugs point A to B with a voltmeter. Wires 481(red, point A) to 467(blu, point B) and 482(wht) to 468(grn) max volts between them was about 2.5vdc while the ignition sw was ON or at cranking position.
Does this tells you anything? Pls advice...
Ok so you have voltage to the positive side of the injectors. That means that you are missing the pulse which is the momentary ground that causes the injector to activate. This pulse signal comes from the distributor and goes into the computer. Being that you have spark, tells us that the distributor is good.
This indicates that the ECM (engine control module) or the computer is not providing the signal First check the grounds to the computer. Terminal A12 and D1 both Black/White should be ground. If they are good, a typical problem is that the "quad drivers" go bad and they generally go bad if the fuel injector resistance is too low.
You would need to replace the ECM and check the fuel injector resistance. If you take an ohm meter and test the fuel injector with the wires disconnected, the reading should be from 1.16 ohms to 1.36 ohms. If they are out of range, replace them.
Also check that the ESC module terminal 486 (D shown on the wiring diagram) has a good ground too.
Hi Vinny, its been a couple of days!
I did all tests that you have asked me to do.
On ECM checked A12 and D1 to ground, found both good ground.
Checked injectors resistance wire disconnected, found withing range about 1.2 ohms for each one.
On ESC module term (486) D also found good ground.
On ECM D16 and D14 checked continuity on wires from computer to the injectors, found both good. D15 and C15 are not used, sockets are empty on the plug.
With plug connected to computer cranked the engine and checked with test light between positive battery terminal to D16 and D14, no test light pulses.
Last test I did was to jump together D16 and D14 with a piece of wire and took the other end of the wire to a clean spot on the chassis and touched it on/off as fast as could while cranking the engine. Engine started and it kept running for as long as I kept doing the chassis on/off action with this wire. I did this test twice, engine ran on both tests.
Finally, I jumped A-B on the ALDL to check for any message from the ECM. Only code was 12 (it cycled for more than 4x).
What do you suggest next? If it is replacing the ECM, how is the procedure to replace it? And if you recommend any online autoparts. I already checked locally around here and no autoparts have it. By the way, I live in Aruba, its an island near the cost of Venezuela.
Thank you Vinny.
Albert
Hi, Sorry, I was out of town and I just got back. Let me review this and I will give you an answer later tonight.
I am waiting your advice how to proceed.
Pls can you answer asap?
Thank you.
hello... i'm another expert with Just Answer. i know you've done alot of testing here... but if you could give me a list of any parts replaced and whether they were new or used... also, if there is ANY type of theft system/alarm installed on this vehicle? lastly, was there any work done to this vehicle prior to this issue happening? thank you for getting me this info.
also, there is a "check" i'd like you to perform... if possible. take some brake clean/carb clean and spray a small amount into the TBI. crank the engine and see if it starts-runs-then stalls. please reply with findings... thanks again.
Hello Dear Sir:
Parts or work done on vehicule prior to this issue, none.
Parts replaced after this issue: only inline gas filter and ECM (remanufactured).
No theft/alarm system installed.
"checked" as requested. engine starts-runs-stalls. repeated four times, ok.
Pls can you advice further checks?
AC
Hello dear Sir:
Yes i did checked for sparks, ok.
What I'm not getting are fuel infectors firing. Checked fuse labeled ECM-1 and positive volts to injectors is present while cranking. The only thing that seems missing is the ECM not pulsing the momenary ground to complete the loop and fire the infectors. I already checked ECM ground wires and injectors wires continuity from end to end as per attached diagram sent by Expert #1. He advised to replace ECM and to check injectors resistance which I found to be about 1.2 ohms which is within range as he explained.
If I complete the loop from fuse ECM-1 through injectors then to D14/16 to ground then i get the injectors to fire manually, even start and keep the engine running for a while as if I keep pulsing fast enough to ground.
I replaced the ECM with a remanufactured one, moved the chips from the original to the new, installed it as per recommendations, but, still have the same problem, injectors are Not firing through the ECM module.
I appreciate all the help that I could get.
Many thanks,
Chevrolet tecnician
Over 25 years experience,GM grand master for 8 years,certified smog and government safety inspector
Hello dear Sir Billy:
Yes I did replace the ignition module and pick-up and the problem was solved.The damage was visible on the pick-up coil and I just replaced both of them at the same time as per your advice.
You guided me exactly to where the problem was. You are really good at what you do.
I want to thank you Billy for your smart advice that took me straight to where the problem was, also thank you for your followup...
I also want to thanks Vinny for the initial help he gave me.
Regards and Happy New Year 2009,
Aruba, Netherland Antilles.