No injector pulse?

[raiper]

ok smark ones im being dumb again now i dont have fuel going through the injectors, or atleast i believe so. I hooked up a 194 bulb assembly from a turn signal. unhooked an injector plug and put the wire in from the light assembly and the light doesnt flash...i was thinking i could use it as a cheap noid light, but i guess not or the injectors arent getting a pulse. But boy do i get sparK! shocked the shit outta me the other day. is there any relay or fuse or other connector that controls the FI or would it be a computer issue?

 

[superranger4.0]

check to see if you have power at your injector the 194 bulb will work for this. key on for this.

 

[raiper]

i would have to say no power at the injector

 

[F150hybred]

Don't the injectors work on mili-volts and not volts?? If that is the case, wouldn't a "typical" 194 bulb not work?? I don't know myself, but just figured I would throw that out there.

 

[Ranger44]

I don't think it would work.

I'd say a better choice is to use a stethiscope.

They are cheap....like $5.

You can listen to the pulses and the difference in pules as the vehicle is running, and is in my opinoin a better way to check injector pulses.

 

[MAKG]

Noid lights aren't much more expensive than that.

They switch on (nearly) full battery voltage, though you won't see it with a standard DC voltmeter. But the frequency might be a bit tough to work. Incandescent bulbs work by heat, so are you going to heat it up enough in the 1/7 sec you have at idle?

You CAN hear a good injector "click" with a stethoscope. And there likely IS a good signal to the injectors if only one is out. 1992s are still bank-fired, so a dropped-out signal will kill THREE or SIX injectors.

 

[raiper]

i cant get it to idle or start period but im getting spark and air

 

[smokey]

Try a little starting fluid or a squirt of gas down the throttle body to see if it will start.
If it does you will know it is not getting fuel and work from there. Check the connections to the injector harness and your grounds.

 

[superranger4.0]

Yes you have or should have battery voltage at the injector and you pcm with pulse a ground to mthe injector. so if you have no power i wolud start checking fuses and wiring first. so you 194 will still work.

 

[superranger4.0]

you will have to go to a known good ground and to the injector connector i want to say its the solid orange wire but just try both.

 

[shadetree]

In checking the injectors with the engine off, key on, you should have battery voltage on both injector wires. If you are using an analog voltmeter, with the positive probe on the tan wire, you will see the needle fluctuate slightly as it fires when cranking the engine.

Using a standard test light on the tan wire, you will see the light dim slightly as the injector pulses if is is working correctly. You will not see a "flash" with an incandescent bulb. shady

 

[raiper]

im using a digital voltmeter now...the 194 buld thing wasnt working for me in the daylight hours. I did a ohm test on the injectors and they are within specs and to test the injector clip i didnt get anything on regular V but i did i believe on mV. ill have to double check that later tonight

 

[raiper]

does anything else control the injectors beside the PCM. is there a relay that controls it? just converted it over to a manual btw and have spark. have the manual PCM in as well

 

[MAKG]

Screw the DVM. Use an oscilloscope, a tach, or a dwellmeter. The oscilloscope is by far the best solution.

You're boxcar-sampling over a square wave. So, your measurement essentially tells you the duty cycle times the amplitude. If you know the duty cycle from another source, you can solve the equation. Otherwise, you can't disentangle them and just don't know.

Injectors are grounded by the PCM. Of course there is a bunch of wiring in between, and the PCM has to have all its inputs. There is MUCH to check before condeming the PCM.

Use the correct tool for the job, or you're going to end up guessing. Replacing a good PCM or a set of injectors compares to a couple of hours of competent diagnosis. I doubt it will require that much.

 

[raiper]

well i would have to say im not getting any injector action. i hooked up DV to it and got 2.195 V or something and it fluctuated when cranking. like that and i got it to run on the rag...rag soaked in gas over the intake, but after it gets what gas it can off the rag it dies. I dont have any other fancy tools for the job. Im wondering if it would be worth the bother to grab a whole PCM, Engine, and Trannsmission harness from a manual truck instead of using the automatic wiring.