atomic_fungus (atomic_fungus) wrote,
atomic_fungus
atomic_fungus

#3561: At least two really leaky injectors.

I borrowed Og's rig for testing fuel injectors today. It's pretty simple: a fixture to hold the injector, some piping to hold cleaning fluid, a regulator with a standard compressor fitting to pressurise the pipe, and a ball valve through which additional fluid can be added.

Seperately, there's a pushbutton switch with a couple of alligator clips for hooking to a battery, and then a plug for connecting to the fuel injector. Press the button, the injector opens; release it, it closes.

Put fluid in the pipe, close the valve, connect the air line, and press the button. What could be simpler?

...well, after I spray-painted the garage door with Heet a couple of times, I learned to make sure the valve was closed before supplying air.

But aside from failures caused by human error, the fixture worked extremely well.

Out of the injectors that came from the car, two were leaking pretty badly. Wipe the tip clean with a paper towel, wait a few seconds, and a drop would form. To ensure it wasn't fluid leaking from around the top of the injector, I wrapped the thing with more paper towel to absorb anything that might be dripping, and these injectors still had drops on their tips after a few seconds' wait. Leaky injector=bad, so I set them aside.

Two of them, I couldn't tell what their status was because their o-rings weren't making a good seal against the fitting, so cleaning fluid was trickling down all over them.

Two, then, worked fine--stuff came out when the button was pressed, and none came out when it wasn't.

Then I turned my attention to the other set of injectors, the spare one.

They all worked fine, but for one, which refused to fire until I took it off the stand and knocked its business end against the workbench a couple of times. Then it worked just fine. Considering that this set has been sitting in the garage since 2004, it's not terribly surprising, and I'd wager this one will be just fine.

I was even able to test the cold start injector. Og hadn't designed this thing for such a test, but I discovered that the pipe threads in the ball valve were exactly the right size for me to screw in the cold start injector:



I filled the pipe with carb cleaner, then lay the whole fixture on its side, screwed in the cold start injector, and applied pressure. (Of course I had to have an injector in the fixture to seal that end off. Worked fine.) And when I pressed the button, the cold start injector sprayed, and when I didn't, it remained dry.

So: the cold start injector doesn't leak at all, and works perfectly. But since at least two of my injectors were severely leaky, that alone could account for the way the engine was running.

Anyway, so I assembled the spare fuel rail with the spare injectors, and was going to put them in...until I had a gander at the lower plenum and intake manifold. It's a mess, so I'm going to take the shop vac out there tomorrow and hold the hose over the manifold while working with a small brush, so I can get at least some of that crap off the thing before I button it up.

Old injector ('85) on the left; new injector ('86) on the right:



The old ones are pintle-type, and the new ones are disk-type. Shouldn't make too much of a difference, I'm told. The ones on the right have a better spray pattern, though.

And this image shows how crummy everything is, and what a disaster the engine compartment is right now:



So hopefully tomorrow--around everything else I have to do (therapy and choir practice. Whee!)--I can get some major work done on the Fiero.

But at least I'm getting somewhere.
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