I think a fuel injector is stuck open on my 97 Ranger 3.0. How can I check to see if I'm right and which one it is? I've heard about the "listening to the injectors" trick but I'm not sure what procedures to go through. Can I tell if one is open by taking them out and visual inspecting?

 

You really don't want to disturb the seal by pulling them out unless you have to. You can buy a cheap mechanic's stethoscope at some auto parts stores, or take a wooden dowel or even a long-handled screwdriver and put one end on the injectors, one at a time, of course, and the other end to your ear and listen for the ticking that will signify that the injectors are cycling. Umm, if you use the screwdriver trick, be sure to put the handle end on your ear and the tip on the injector. Could be a little uncomfortable the other way around, not to mention the potential for punching a hole in your eardrum! -TD

 

I appreciate that man. I also appreciate the screwdriver warning! LOL!

 

Why do you think an injector is stuck open? The more common problem is the diaphram rupturing in the fuel pressure regulator. This can be checked by pulling the vacuum line of the regulator and checking for raw gas.

 

One problem is that my truck is hard to start when it is hot. I read in my Haynes manual that it could be a sign of a fuel injector being stuck open. The bad thing is that I can't reach 2 of the injectors with the stethascope to listen to them. These two I can't even see without taking off the manifold.

 

Hello! gmnetum new menber here,Ford trained tech Bucksport maine. One way to begin to isolate a leaky fuel injector is to gather clues. Once fuel is pumped up into the fuel rail pressure should remain constant at KOEO (key on engine off) If you had a fuel guage connected to your schrader valve test port on the fuel rail and you had the key in KOEO you would see pressure in access of 35 psi (depending on vehicle and engine size) some moreso. if you pressure leaks down,even minutely. then either the check valve in the fuel pump is not doing it's job or the diaphram in the fuel regulator is punctured OR you have a leaking injector. If you have a badly enough leaking injector the cylinder would be flooded and would not be contributing. This can be verified easliy also by disconnecting the injector and if the engine still runs poorly/or the same(in other words no different after disconnecting the injector ) then you have found your "Bad Hole" and now know which cylinder the problem is in. hope that helps. and please let everyone know that I have all manuals,TSB"s PCED"S and schematics from 96 to 2001 on my puter. Hope that helps. gmentum

 

Also you could just remove and visually inspect the spark plugs to find one that may be excessively fueling. gmentum@peoplepc.com

 

also listening to the injectors may not give you anything new to decipher. an injector may be firing well but just cant close it's pintle. I have found that you can remove most fuel rails with injectors intact on the rail and electrical connector side and suspend them and watch them again KOEO some will leak so bad that you dont even need to turn the key KOEO. I use some trans lube or axle grease to easily coax the seals back into there place in the intake manifold. And make sure you install the "o" rings on the injectors then install them into the intake manifold! gmentum

 

Look at the plugs...if the injector is indeed stuck open it will probably be wet, with the others being very white as the computer compensates for the rich condition by running the other cylinders lean.

I would definately look at the fuel pressure first. Gmentum is correct in that you can easily check for a leaky injector by pulling the rail with injectors connected and turning the key on and off a few times to build pressure in the lines and looking for leaks. Actually you MUST lightly lubricate the o-rings on the injectors to aid in installation; it allows them to slide into the bores in the manifold instead of hanging up and tearing or cutting them. Just use some motor oil, I would be hesitant to use axle grease around the tips of the injectors for fear of clogging them.

 

​​​​​​​My '97 3.0 ranger had rough idle, low power, bad mileage and bucked and skipped at low rpm under any load. No codes for misfire. After checking everything I could think of, I turned to the injectors. I had recently overhauled the motor for this worsening problem and, although it got better, it still had the same problems. All the injectors were cycling normally (did the screwdriver test). The only injectors I could reach without taking the intake riser off were 1,2, &3. I disconnected #3 (engine running) and no change. Reconnected it and disconnected #2. Engine skipped worse. Reconnected #2 and disconnected #1. Engine almost died. Took the intake off and changed all 6. Got a set of 6 for $79 on Amazon. Looked at #3 and found it stuck wide open. After replacing injectors, it runs like a new truck.