I know there are ten thousand answers already I have been through the them all. The low down, Bronco stopped running last summer I have been through everything and it has tested good in fuel and ignition systems. On a whim to see spark from the coil I put my spark tester going from the coil wire to the top of the distributor and it fired right up. Took the tester out and it would not fire. I tried a new wire and same thing no start. Put tester back in line and it fired back up. Anyone have an idea what would cause this?

 

Your spark tester has a spark gap itself, right?

A trick I used for years on lawnmower engines that did not want to start was to disconnect the plug wire, and have it close to the plug's end. In effect, putting another small spark gap in series with the plugs own gap. Often, that would get it to pop and run a bit. Root cause was old gas, fouled spark plug, or spark plug insulator in cylinder wet with gas (good gas or bad gas).

 

Did you check your plugs and wires? Cap and rotor?

 

I am having similar problems with my 91 bronco. It's been sitting up for several years and would never engage the starter but it ran before so I got the issue fixed with the starter now it will only run on starting fluid or barely run if I feather the throttle. I've already drained all the old gas, put in a new fuel filter, drained old gas out of the fuel rails several times, I'm just wondering if I might have clogged injectors from trying to start it with the old gas or if I might have a sensor out somewhere just don't know where to go from here

 

To answer all of the questions yes I have checked it! I gave up and took it the mechanic and let them play with it! Ill let you know what they do to fix it!

 

To get this right you were testing from the ignition coil to the distributor with your spark tester?

I've never used a spark tester so I don't know how they work/what they look like but I know I did have a starting issue long ago with my 5.0. What it ended up being is that there are two wire (I believe) that go from the ignition coil to the distributor. On my Bronco (96), one of those wires was white. The white wire had connecting issues so it wasn't letting the ignition coil send spark to the distributor. The white wire seemed okay , but I ended up cleaning it up and making sure the connections were good. I never had an issue with that again. I remember reading this was a somewhat common issue with this wiring as well.

So maybe take a look at that if you get a chance or the mechanics don't seem to find anything wrong!