one cylinder isn't firing on my 1987 Ranger

[greaseyfingers]

The number 2 cylinder fuel injector isn't firing on my Ranger's 2.9 engine.

The fuel injector's ohm resistence measured 15 ohms.

I think 15 ohms is within specs, isn't it?

When I grounded my continuity tester and checked for power on the fuel injector's wire connector plug terminal.

The continuity tester's light comes on when I touch it to each of the wire terminals on this connector.

On this fuel injector wire connector, isn't one of the two terminals suppose to be for power and the other one for a ground?

Why would it be lighting up the coninuity tester when touching it to each individual termanal on the fuel injector's wire connector plug?

Has anyone had this problem, before, and what's the remedy to fix it?

 

['99 EB Explorer]

Check for any breakage in the wire insulation. There's power getting into the ground wire that shouldn't be there...

 

[greaseyfingers]

Check for any breakage in the wire insulation. There's power getting into the ground wire that shouldn't be there...

I wonder how the power could be getting into the ground wire, without shorting something out, somewhere?

Where do these wires go to from the fuel inector's connector plug, the computer or ignition module?

I didn't see any broken insulation on these short lengths of insulated wires that the fuel injector's connector plug is attached to, coming out of the wiring harness.

So, now what's the next step?

Do I need to take the wiring harness apart and follow these wires back to where ever they go?

Or, is there an easier way to find it?

 

[Bent Bolt]

Ford PCM's use ground side switching . One terminal will have constantly 12V when key on. The other side is the PCM controled ground. If there is 12V on that circuit there is a short to volts or PCM failure.

 

[greaseyfingers]

Ford PCM's use ground side switching . One terminal will have constantly 12V when key on. The other side is the PCM controled ground. If there is 12V on that circuit there is a short to volts or PCM failure.

Is the possible PCM failure you're talking about, the TFI ignition module?

If the PCM fails and doesn't send a ground wire signal to the fuel injector, for firing it.

Does the fuel injector's ground wire then become a hot wire, instead?

 

[doorgunner]

I had a similar problem on my'89 Ranger.....I chased wires for hours.....ended up finding green corrosion in one of the connectors that the injector harness tied into.....spent a good hour cleaning the green crud off the male pin connector & another hour cleaning the tiny holes in the female connector....

injector squirted great after that.....


might not be your problem though

 

[straycat]

Could be a bad injector. That happend on my wife's Mustang. I thought it was a plug wire and I bought new wires and there was still a miss. I then yanked out that injector and put in a new one and it was back to normal. At least she got new wires for it...lol

 

[greaseyfingers]

I had a similar problem on my'89 Ranger.....I chased wires for hours.....ended up finding green corrosion in one of the connectors that the injector harness tied into.....spent a good hour cleaning the green crud off the male pin connector & another hour cleaning the tiny holes in the female connector....

injector squirted great after that.....


might not be your problem though

When you said that you "ended up finding green corrosion in one of the connectors that the injector harness tied into.

Do you recall where this connector was that the injector harness tied into?

There are a lot of connectors located along the driver's side fender on my 1987 Ranger.

I've already cleaned all the connectors that I've been able to pull apart.

Some of the connectors, I haven't been able to pull apart and clean, as they're held together too tight.

So far, I've been reluctant to use too much force and possibly break any of the connectors that aren't willing to seperate.

What's the best way to get a stubborn connector apart thats not willing to seperate, without breaking it.

I've been spraying WD-40 on them, hoping that might help to loosen them up enough to be able seperate them, for when I try to seperate them, again, later.

 

[AllanD]

the Injectors are supplied with 12volts POS AT-ALL-TIMES...


because EEC switches the GROUND to fire the injector


AD

 

[greaseyfingers]

the Injectors are supplied with 12volts POS AT-ALL-TIMES...


because EEC switches the GROUND to fire the injector


AD

If the Injectors are supplied with 12volts POS AT-ALL-TIMES until the EEC switches the GROUND to fire the injector, as you stated.

When I have my coninuity test light grounded on the engine and probe each of the two fuel injector wires, seperately, while the key is on and use my remote starter switch attached to the starter's solenoid, to turn the engine over.

Neither of these two wires on the fuel injector's connector, will make my conintuity test light blink, when they are being probed, seperately, as the engine is being turned over, with the key on and using my remote starter switch.

If the EEC is properly controlling the ground to fire the injector.

One of the two wires on the fuel injector's connector, should make my continuity test light keep blinking on and off, shouldn't it, as the engine is being turned over with the key on and using my remote starter switch to active the starter's solenoid.

Or, won't a coninuity test light, work for doing this kind of test procedure?

Does a Noid Light, need to be used, instead of a coninuity test light, for being able to detect the EEC ground signal for blinking the light on and off, as it's detecting this signal for firing the fuel injector?

 

[robertc1024]

AllanD is exactly right. And you would have continuity at both terminals unless the coil in the injector was open. I'd use an oscilloscope if you've got access to one. You can hook the o-scope to either side and see what electrical signals the injector is getting. If not any, then you can start chasing wires to the ECU like Doorgunner said.

I don't know for sure but I would bet your continuity tester won't blink because the pusle width going to the injector is too short. It varies from ~5 to ~35 mS long.