My neighbor has a "FORD" mustang that he converted over to MASS AIR Multi-Port. Now number 4 cylinder injector is steady flowing fuel. When I probed the connector with the key off I found 1.5 volts on the ground pin?
Now I know this is a CORVETTE forum, but I was just wondering if anybody had any ideas?
Does anybody know of a Mustang place on the Internet where I might find the same helpful info that I have found here?
Before you start hating me, I don't own a mustang, I have a RUBY Auto Coupe. I'm just trying to help a neighbor.

 

I would be chasing the harness. it sounds like there is a dead short in the circuit somewhere.

check the resistance of the injector. It should be about 15 ohms or so. they are similar to the injectors used on the vette.

 

There are a couple of checks you need to make. I would start by reconnecting the injector, start the engine and listen to the injector with a stethoscope to see if it is clicking.

If it is not clicking, I would connect a NOID light to the connector for that injector and see if it is pulsing. The fact that you are getting voltage may not be conclusive because that is where the injector is switched. That is, there is voltage on the injector any time the key is on, but it is turned on by the ECM providing a ground. Finding voltage on the ground may not mean anything if the injector is not being switched at the time you are looking at it.

Lastly disconnect the injector electrically and see if it is still flowing fuel.

Basically if the NOID light is flashing, I would think that it's a really good bet that you have a bad injector. If the NOID light is not flashing then you have a wiring harness or ECM problem.

BTW, don't be ashamed to be talking about a Ford. They make good cars too. Brand loyalty is fine, but there are lots of good cars on the road that weren't made by GM.

Edited: Bogus posted before I could finish mine. Yes indeed the wiring harness could be the problem, but I would NOT start chasing the harness before testing with a NOID light. A NOID light is really cheap and if it is flashing, then chasing down the harness would definitely be putting the cart in front of the horse.

Good luck,

 

The noid light showed that the injector is always flowing fuel with the engine running(It glows steady, no pulse). It flows so much fuel that you can see the exhaust and smell the fuel. When we disconected the injector the exhaust cleared up, that's what led to the probing of the wiring harness.

 

Good deal, you're on the right track. While running down the harness, remember that it is the ground side to the injector that is switched. The hot is there any time the key is on.

If you have a wiring diagram, you could go to the pin on the ECM connector and see if it looks the same electrically as what you are seeing at the injector. If it does not then you know the problem is in the harness. If so, then the problem is in the ECM.

Good luck,

 

Thanks for the input. I am not against any other brand of vehicle. I own a Ford truck and a Mercury Grand Marquis, just wanted to say that I know this is Corvette forum and Ford questions are a little off topic. Thanks again for your thoughts.